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VERSION:2.0
PRODID:GeomGrav
BEGIN:VEVENT
UID:geomgrav-2022-06-27-08-30-00
DTSTAMP:20241004T184040Z
SUMMARY:Registration / Technical testing
DESCRIPTION:
DTSTART:20220627T053000Z
DURATION:PT30M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-09-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Opening words
DESCRIPTION:
DTSTART:20220627T060000Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-09-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Modified theories of gravity - foundations and models
DESCRIPTION:Christian Boehmer (University College London, London, United
Kingdom)\n\nModified theories of gravity - foundations and models\n\nIn
the first part of the talk I am discussing General Relativity, in parti
cular its basic ingredients and its mathematical structure. This will na
turally lead the way to consider various modifications or extensions of
General Relativity, many of which have been studied recently. Next I wil
l discuss modified gravity models based on generalised geometries and on
actions no longer linear in curvature. The main part of the talk will d
iscuss how these many different theories can be studied using a single u
nified approach which also shows the equivalence of some of these models
. Boundary terms in the action will play a crucial role in establishing
the equivalence between different theories. The final part discusses the
study of cosmological models using dynamical systems techniques.
DTSTART:20220627T061500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-10-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Registration / Coffee Break / Poster Viewing
DESCRIPTION:
DTSTART:20220627T071500Z
DURATION:PT30M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-10-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Beyond Einstein’s General Relativity: Hybrid metric-Palatini g
ravity and curvature-matter couplings
DESCRIPTION:Francisco Lobo (Institute of Astrophysics and Space Sciences
, University of Lisbon, Lisbon, Portugal)\n\nBeyond Einstein’s General
Relativity: Hybrid metric-Palatini gravity and curvature-matter couplin
gs\n\nEinstein’s General Relativity (GR) is possibly one of the greate
st intellectual achievements ever conceived by the human mind. In fact,
over the last century, GR has proven to be an extremely successful theor
y, with a well-established experimental footing. However, the discovery
of the late-time cosmic acceleration, which represents a new imbalance i
n the governing gravitational field equations, has forced theorists and
experimentalists to question whether GR is the correct relativistic theo
ry of gravitation, and has spurred much research in modified gravity, wh
ere extensions of the Hilbert-Einstein action describe the gravitational
field. In this talk, I perform a detailed theoretical and phenomenologi
cal analysis of two largely explored extensions of f(R) gravity, namely:
(i) the hybrid metric-Palatini theory; (ii) and modified gravity with c
urvature-matter couplings. Relative to the former, it has been establish
ed that both metric and Palatini versions of f(R) gravity possess intere
sting features but also manifest severe drawbacks. A hybrid combination,
containing elements from both formalisms, turns out to be very successf
ul in accounting for the observed phenomenology and avoids some drawback
s of the original approaches. Relative to the curvature-matter coupling
theories, these offer interesting extensions of f(R) gravity, where the
explicit nonminimal couplings between an arbitrary function of the scala
r curvature R and the Lagrangian density of matter, induces a non-vanish
ing covariant derivative of the energy-momentum tensor. I explore both t
heories in a plethora of applications, namely, the weak-field limit, cos
mology, and irreversible matter creation processes of a specific curvatu
re-matter coupling theory.
DTSTART:20220627T074500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-11-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Lunch
DESCRIPTION:
DTSTART:20220627T084500Z
DURATION:PT75M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Identification of some redundant operators and a generalized Ein
stein frame in MAG theories
DESCRIPTION:Adrià Delhom I Latorre (University of Tartu, Tartu, Estonia
)\n\nIdentification of some redundant operators and a generalized Einste
in frame in MAG theories\n\nInspired by recent findings involving Ricci-
Based Theories, in this talk I will argue why, for theories reproducing
GR at low energies which admit a perturbative expansion for the higher o
rder corrections, and for which derivatives of the metric do not appear
in the Lagrangian, the terms containing R_((μν))^(Γ) beyond the Einst
ein-Hilbert term can be understood as redundant operators (in the Effect
ive Field Theory sense) that can be reabsorbed into the interactions of
the matter sector. At the same time, the form of the field equations sug
gests that the metric which describes gravitational perturbations is not
the one in the original frame of the theory, namely g^(μν), but rathe
r an object q^(μν) defined from the derivatives of the Lagrangian with
respect to R_((μν))^(Γ). I will then try to outline the construction
of a sort of generalized Einstein frame where q^(μν) acts as an effec
tive metric.
DTSTART:20220627T100000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Junction conditions in Palatini f(R,T) gravity
DESCRIPTION:João Rosa (University of Tartu, Tartu, Estonia)\n\nJunction
conditions in Palatini f(R,T) gravity\n\nWe work out the junction condi
tions for the Palatini f(ℛ, T) extension of General Relativity, wher
e f is an arbitrary function of the curvature scalar ℛ of an independe
nt connection, and of the trace T of the stress-energy tensor of the mat
ter fields. We find such conditions on the allowed discontinuities of se
veral geometrical and matter quantities, some of which depart from their
metric counterparts, and in turn extend their Palatini f(ℛ) versions
via some new T-dependent terms. Moreover, we also identify some ``except
ional cases" of f(ℛ, T) Lagrangians such that some of these conditio
ns can be discarded, thus allowing for further discontinuities in ℛ an
d T and, in contrast with other theories of gravity, they are shown to n
ot give rise to extra components in the matter sector e.g. momentum flu
xes and double gravitational layers. We discuss how these junction condi
tions, together with the non-conservation of the stress-energy tensor as
cribed to these theories, may induce non-trivial changes in the shape of
specific applications such as traversable thin-shell wormholes.
DTSTART:20220627T100000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Restrictions in quadratic metric-affine gravity from the stabili
ty of the vector sector
DESCRIPTION:Alejandro Jimenez Cano (Institute of Physics, University of
Tartu, Tartu, Estonia)\n\nRestrictions in quadratic metric-affine gravit
y from the stability of the vector sector\n\nIn this talk we will revise
the stability of the four vector irreducible pieces of the torsion and
the nonmetricity tensors in the general quadratic metric-affine Lagrangi
an in 4 dimensions. This analysis highly constrains the theory and reduc
es the parameter space of the quadratic curvature part from 16 to 5 para
meters. We will also mention the case of Weyl-Cartan gravity, proving th
at the stability of the vector sector completely fixes the dynamics of t
he full Lagrangian to just an Einstein-Proca theory or pure General Rela
tivity.
DTSTART:20220627T102500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Matter properties vs gravity
DESCRIPTION:Aneta Wojnar (Laboratory of Theoretical Physics, Tartu, Esto
nia)\n\nMatter properties vs gravity\n\nI will review a few last finding
s related to properties of matter in stellar objects in metric-affine th
eories of gravity.
DTSTART:20220627T102500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:The Full Quadratic Metric-Affine Gravity: Solving for the Affine
Connection
DESCRIPTION:Damianos Iosifidis (Aristotle University of Thessaloniki, Th
essaloniki, Greece)\n\nThe Full Quadratic Metric-Affine Gravity: Solving
for the Affine Connection\n\nWe consider the most general Quadratic Met
ric-Affine Gravity setup in the presence of generic matter sources with
non-vanishing hypermomentum. The gravitational action consists of all 17
quadratic invariants (both parity even and odd) in torsion and non-metr
icity as well as their mixings, along with the terms that are linear in
the curvature namely the Ricci scalar and the totally antisymmetric Riem
ann piece. Adding also a matter sector to the latter we first obtain the
field equations for the generalized quadratic Theory. Then, using a rec
ent Theorem, we successfully find the exact form of the affine connectio
n under some quite general non-degeneracy conditions. Finally we shall d
iscuss the consequences and also applications of our result.
DTSTART:20220627T105000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Collapsing stars in f(R) gravity
DESCRIPTION:Adrián Casado-Turrión (Universidad Complutense de Madrid,
Madrid, Spain)\n\nCollapsing stars in f(R) gravity\n\nGravitational coll
apse is still poorly understood in the context of f(R) theories of gravi
ty. The archetypal Oppenheimer-Snyder model (which is an exact solution
of General Relativity) is known to be incompatible with the junction con
ditions of f(R) gravity, both in the metric and Palatini formalisms. In
this talk, we shall explain how the Oppenheimer-Snyder construction must
be generalised so as to fit within f(R) models of gravity. By means of
a systematic analysis of the relevant junction conditions, we will show
that some paradigmatic vacuum metrics cannot represent spacetime outside
collapsing stars in f(R) gravity.
DTSTART:20220627T105000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:ALP dark matter from torsion
DESCRIPTION:Francisco José Maldonado Torralba (University of Tartu, Tar
tu, Estonia)\n\nALP dark matter from torsion\n\nIn this talk I will expl
ain how the pseudoscalar degree of freedom of the quadratic Poincaré Ga
uge theory of gravity can act as a dark matter candidate. I will give th
e parameter space of the theory for which such dark matter candidate can
account for all predicted cold dark matter, and constrain such paramete
rs based on current astrophysical observations.
DTSTART:20220627T111500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Stable Hydrogen-burning Limits in Rapidly Rotating Very Low Mass
Objects
DESCRIPTION:Shaswata Chowdhury (Indian Institute of Technology Kanpur, K
anpur, India)\n\nStable Hydrogen-burning Limits in Rapidly Rotating Very
Low Mass Objects\n\nWe present novel effects of uniform rapid stellar r
otation on the minimum mass of stable hydrogen burning in very low mass
stars, using an analytic model and relaxing the assumption of spherical
symmetry. We obtain an analytic formula for the minimum mass of hydrogen
burning as a function of the angular speed of stellar rotation. Further
, we show the existence of a maximum mass of stable hydrogen burning in
such stars, which is purely an artifact of rapid rotation. The existence
of this extremum in mass results in a minimum admissible value of the s
tellar rotation period of ∼22 minutes, below which a very low mass obj
ect does not reach the main sequence, within the ambit of our model. For
a given angular speed, we predict a mass range beyond which such an obj
ect will not evolve into a main-sequence star.
DTSTART:20220627T111500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-14-40-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220627T114000Z
DURATION:PT20M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:New black hole solutions with a dynamical traceless nonmetricity
tensor in Metric-Affine Gravity
DESCRIPTION:Jorge G. Valcarcel (University of Tartu, Tartu, Estonia)\n\n
New black hole solutions with a dynamical traceless nonmetricity tensor
in Metric-Affine Gravity\n\nIn the framework of Metric-Affine Gravity, w
e focus on the dynamical role of the traceless parts of the nonmetricity
tensor and construct new static and spherically symmetric black hole so
lutions with independent shear charges.
DTSTART:20220627T120000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Gravitational wave observation as a tool for validating modified
gravity in white dwarfs
DESCRIPTION:Surajit Kalita (University of Cape Town, Cape Town, South Af
rica)\n\nGravitational wave observation as a tool for validating modifie
d gravity in white dwarfs\n\nAfter predicting many sub- and super-Chandr
asekhar limiting mass white dwarfs from the observations of peculiar typ
e Ia supernovae, researchers proposed various models which can separatel
y explain these two classes of white dwarfs. We have shown that these tw
o peculiar classes of white dwarfs, along with the regular Chandrasekhar
white dwarfs, can be explained by a single form of modified gravity, wh
ose effect is significant only in the high-density regime, and it almost
vanishes in the low-density regime. Thereby it can explain the violatio
n of the Chandrasekhar mass-limit of 1.4M_(⊙). However, so far, there
is no direct detection of such white dwarfs, and hence it is difficult t
o single out one specific theory of gravity. In my talk, I’ll show tha
t gravitational wave observation is one of the prominent ways to single
out the exact theory of gravity. We estimate the amplitudes of all the r
elevant polarization modes of gravitational waves for the peculiar and r
egular white dwarfs and thereby discuss their possible detections in the
future through some of the proposed gravitational wave detectors, such
as LISA, ALIA, DECIGO, BBO, or Einstein Telescope. This exploration link
s the theory with possible observations through the gravitational waves
in modified gravity.
DTSTART:20220627T120000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Spherically symmetric spacetimes in metric-affine Chern-Simons g
ravity
DESCRIPTION:Flavio Bombacigno (Universitat de València, Valencia, Spain
)\n\nSpherically symmetric spacetimes in metric-affine Chern-Simons grav
ity\n\nWe discuss some recent developments for the metric-affine formula
tion of Chern-Simons gravity, where projective invariance is recovered b
y enlarging the Pontryagin density definition with nonmetricity dependin
g terms. In particular, we show how analytical solutions for the metric-
affine structure can be obtained in spherically symmetric spacetimes, by
requiring the absence of dynamical instabilities which we demonstrate t
o be generated by peculiar components of the affine connection. Finally,
we present some exact solutions for the homogeneous and isotropic cosmo
logical background and we discuss in details how the propagation of grav
itational waves is affected with respect to the metric formulation.
DTSTART:20220627T122500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Gravitational Waves in ECSK theory: Robustness of mergers as sta
ndard sirens and nonvanishing torsion
DESCRIPTION:Fernando Izaurieta (University of Concepcion, Concepcion, Ch
ile)\n\nGravitational Waves in ECSK theory: Robustness of mergers as sta
ndard sirens and nonvanishing torsion\n\nThe amplitude propagation of gr
avitational waves in an Einstein-Cartan-Sciamma-Kibble (ECSK) theory is
studied by assuming a dark matter spin tensor sourcing for spacetime tor
sion at cosmological scales. The analysis focuses on a weak-torsion regi
me, such that gravitational wave emission, at leading and subleading ord
ers, does not deviate from standard General Relativity. We show that, in
principle, the background torsion induced by an eventual dark matter sp
in component could lead to an anomalous dampening or amplification of th
e gravitational wave amplitude, after going across a long cosmological d
istance. The importance of this torsion-induced anomalous propagation of
amplitude for binary black hole mergers is assessed. For realistic late
-universe astrophysical scenarios, the effect is tiny and falls below de
tection thresholds, even for near-future interferometers such as LISA. T
o detect this effect may not be impossible, but it is still beyond our t
echnological capabilities.
DTSTART:20220627T122500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Black hole perturbations in metric-affine Chern-Simons modified
gravity
DESCRIPTION:Simon Boudet (University of Trento, Trento, Italy)\n\nBlack
hole perturbations in metric-affine Chern-Simons modified gravity\n\nThe
Chern-Simons theory of gravity is obtained by adding the Pontryagin den
sity to the Einstein-Hilbert action of General Relativity. This addition
al term is a topological, parity violating term, which arises in differe
nt contexts such as quantum field theory, string theory and loop quantum
gravity. When the coupling to the Chern-Simons term is promoted to a (p
seudo)-scalar field, the field equations are modified, offering interest
ing theoretical insights and new phenomenological predictions. In this t
alk I will consider the metric-affine formulation of Chern-Simons gravit
y, presenting a generalization of the theory in which the symmetry under
projective transformations of the affine connection is restored via a m
odified Pontryagin density, which still retains its topological characte
r. The theory comes in two versions, depending on whether a kinetic term
for the scalar field is included in the action or not. However, in both
cases, the scalar field has dynamical character, in contrast to the pur
ely metric version of Chern-Simons gravity. I will show how the connecti
on field equations can be solved perturbatively for the torsion and nonm
etricity tensors, allowing to study the dynamics of the metric and the s
calar field perturbations within the resulting effective scalar tensor t
heory. As a concrete application I will focus on the evolution of tensor
and scalar perturbations on a Schwarzschild background. The parity viol
ating character of the Pontryagin density only affects the axial modes o
f the black hole, whose quasinormal frequencies are modified with respec
t to General Relativity and the purely metric version of Chern-Simons th
eory. Finally, I will discuss the properties of the late time section of
the gravitational signal, showing how a distinctive signature of metric
-affine Chern-Simons gravity is encoded in the exponents of the power la
w tails.
DTSTART:20220627T125000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-15-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Lensing of gravitational waves in Palatini f(R) gravity
DESCRIPTION:Sreekanth Harikumar (National Center for Nuclear Research, W
arsaw, Poland)\n\nLensing of gravitational waves in Palatini f(R) gravit
y\n\nThe planned next generation of detectors like Einstein Telescope, C
osmic Explorer and space based detectors like LISA are likely detect gra
vitational waves signals more frequently than now. With such an increase
d frequency of detection we expect some of the signals to be gravitation
ally lensed. This lensing phenomenon showcases some interesting features
like diffraction and formation of beat patterns. Another opportunity th
at lensing opens up is to test different theories of gravity. In this wo
rk we study gravitational lensing in the context of Palatini f(R) gravit
y using WKB approximation in the geometric optics limit and beyond.
DTSTART:20220627T125000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-16-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220627T131500Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-16-30-00
DTSTAMP:20241004T184040Z
SUMMARY:Multidimension cosmology in Gauss-Bonnet gravity
DESCRIPTION:Alexey Toporensky (Sternberg astronomical institute, Moscow,
Russia)\n\nMultidimension cosmology in Gauss-Bonnet gravity\n\nA succes
sful compactification scenario should explain two, in principle, rather
different properties of the multidimensional space-time. First, we need
to show why the evolution of three big dimension is different from the e
volution of other dimensions. Second, we need to explain why the 3-dimen
sion subspace is almost isotropic one. We present a scenario which addre
ss both issures. Starting from rather general totally anisotropic initia
l condition the evolution of a Universe naturally leads to a product of
two isotropic subspaces. This presentation is a brief summary of a set o
f papers made in collaboration with A.Giakomini, S.Pavluchenko and D. Ch
irkov.
DTSTART:20220627T133000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-16-30-00
DTSTAMP:20241004T184040Z
SUMMARY:Multi-ring images of regular compact objects
DESCRIPTION:Mercè Guerrero Román (Complutense university of Madrid, Ma
drid, Spain)\n\nMulti-ring images of regular compact objects\n\nWe discu
ss the importance of multi-ring images in the optical appearance of sphe
rically symmetric compact objects, when illuminated by an optically and
geometrically thin accretion disk. On the one hand, we shall consider so
me spherically symmetric black hole and wormhole geometries characterize
d by the presence of a second critical curve, via a uni-parametric famil
y of extensions of the Schwarzschild metric. We will show the presence o
f additional light rings in the intermediate region between the two crit
ical curves. On the other hand, a sub-case of an analytically tractable
extension of the Kerr solution, with both a critical curve and an infini
te potential barrier at the object’s center for null geodesics. Our re
sults point out to the existence of multi-ring images with a non-negligi
ble luminosity in shadow observations.
DTSTART:20220627T133000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-16-55-00
DTSTAMP:20241004T184040Z
SUMMARY:Einstein-Cartan-Maxwell-Holst Gravity and Chiral Magnetic Dynamo
s
DESCRIPTION:Luiz Garcia de Andrade (uerj, Rio, Brasil and Inst. for Cosm
ology Croatia)\n\nEinstein-Cartan-Maxwell-Holst Gravity and Chiral Magne
tic Dynamos\n\nWe review the Einstein Cartan Holst gravity status and in
troduce the Holst current concept as an additional source for cosmologic
al dynamo amplification
DTSTART:20220627T135500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-16-55-00
DTSTAMP:20241004T184040Z
SUMMARY:Linear and Second-order Geometry Perturbations on Spacetimes wit
h Torsion
DESCRIPTION:Omar Valdivia (Arturo Prat University, Iquique, Chile)\n\nLi
near and Second-order Geometry Perturbations on Spacetimes with Torsion\
n\nIn order to study gravitational waves in any realistic astrophysical
scenario, one must consider geometry perturbations up to second order. H
ere, we present a general technique for studying linear and quadratic pe
rturbations on a spacetime with torsion. Besides the standard metric mod
e, a “torsionon” perturbation mode appears. This torsional mode will
be able to propagate only in a certain kind of theories.
DTSTART:20220627T135500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-27-18-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Reception
DESCRIPTION:See Social Program
DTSTART:20220627T151500Z
DURATION:PT165M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-09-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Einstein-Cartan gravity: Inflation and Dark Matter
DESCRIPTION:Mikhail Shaposhnikov (Ecole Polytechnique Federale de Lausan
ne, Lausanne, Switzerland)\n\nEinstein-Cartan gravity: Inflation and Dar
k Matter\n\nIt is well-known since the works of Utiyama and Kibble that
the gravitational force can be obtained by gauging the Lorentz group, wh
ich puts gravity on the same footing as the Standard Model fields. The r
esulting theory - Einstein-Cartan gravity - happens to be very interesti
ng. It may incorporate cosmological inflation driven by the Higgs field
of the Standard Model of particle physics. In addition, it contains a fo
ur-fermion interaction that originates from torsion associated with spin
degrees of freedom. This interaction leads to a novel universal mechani
sm for producing singlet fermions in the Early Universe. These fermions
can play the role of dark matter particles.
DTSTART:20220628T061500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-10-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffee Break / Poster Viewing
DESCRIPTION:
DTSTART:20220628T071500Z
DURATION:PT30M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-10-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Rotating solutions in Ricci-Based Gravity theories and the EiBI
model
DESCRIPTION:Gonzalo J. Olmo (University of Valencia - CSIC, Valencia, Sp
ain)\n\nRotating solutions in Ricci-Based Gravity theories and the EiBI
model\n\nConsidering the EiBI gravity model, I will summarize how one ca
n construct axisymmetric solutions in Ricci-Based Gravity theories (RBGs
) using an algebraic correspondence between RBGs and General Relativity.
If time permits, physical implications for the counterpart of the Kerr-
Newman black hole coupled to Maxwell electrodynamics will be discussed.
DTSTART:20220628T074500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-11-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Group Picture
DESCRIPTION:
DTSTART:20220628T084500Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-12-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Lunch
DESCRIPTION:
DTSTART:20220628T090000Z
DURATION:PT60M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Radiatively stable unitarity in higher-spin models, and applicat
ions in metric-affine gravity
DESCRIPTION:Carlo Marzo (Kbfi, Tallinn, Estonia)\n\nRadiatively stable u
nitarity in higher-spin models, and applications in metric-affine gravit
y\n\nThe scrutiny of gravitational theories beyond Einstein-Hilbert enjo
ys a different standard than flat models probed at collider-level energi
es. Of the proposed extensions, only a subset is explicitly required to
be free of ghosts. Even in such cases, only dipole ghosts are usually ta
rgeted, thus still allowing, in general, wrong-sign states to propagate.
Moreover, even in rare cases where a thorough spectral analysis is perf
ormed, the stability of the resulting action under radiative corrections
is uncertain. In this talk, I discuss the strong constraining power of
requiring, as standard for lower-spin models, a radiatively stable ghost
- and tachyon-free action for the paradigmatic scenario of metric-affine
gravity. I will describe the role of non-accidental symmetries and thei
r interplay with diffeomorphism invariance. I will also provide, in a mo
re general way, an overview of the computational challenges on the way o
f the spectrum of higher-spin theories.
DTSTART:20220628T100000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Black holes in torsional teleparallel gravity
DESCRIPTION:Sebastian Bahamonde (Tokyo Institute of Technology, Tokyo, J
apan)\n\nBlack holes in torsional teleparallel gravity\n\nThe torsional
teleparallel gravity is constructed from a manifold with torsion and zer
o curvature while respecting the metric compatibility condition. In this
talk, I will discuss spherical symmetry in this formalism and present n
ew exact black hole solutions for f(T, B) gravity and also scalarized
solutions from scalar-torsion theories of gravity.
DTSTART:20220628T100000Z
DURATION:PT12M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-12-00
DTSTAMP:20241004T184040Z
SUMMARY:Teleparallel accretion discs and gravitational waves
DESCRIPTION:Christian Pfeifer (University of Bremen, Bremen, Germany)\n\
nTeleparallel accretion discs and gravitational waves\n\nIn this talk I
will present recent results on observables in teleparallel gravity:\n\n-
accretion discs in f(T)-gravity, based on a non-perturbative spherica
lly symmetric solution of the theory\n\n- gravitational wave birefring
ence in new general relativity
DTSTART:20220628T101200Z
DURATION:PT13M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Metric-Affine Gravity as an Effective Field Theory
DESCRIPTION:Oleg Melichev (Scuola Internazionale Superiore di Studi Avan
zati, Trieste, Italy)\n\nMetric-Affine Gravity as an Effective Field The
ory\n\nWe discuss theories of gravity with independent metric (or frame
field) and connection, from the point of view of effective field theory.
In general, in addition to the metric, gravitational interactions can b
e carried by torsion field, or nonmetricity, or both. This theory reduce
s to the General Relativity at low energies in the natural scenario, but
enjoys nontrivial dynamics at high energies as long as dimension four o
perators, such as curvature squared, are considered. We count such opera
tors of even parity and give explicit bases for the independent ones tha
t contribute to the two-point function. We then give the decomposition o
f the linearized action on a complete basis of spin projectors and consi
der various subclasses of Metric-Affine Gravity (MAG) theories. We proce
ed with discussion of ghost and tachyonic instabilities and construct si
mple MAGs that contain only a massless graviton and a state of spin/pari
ty 2- or 3- and therefore are stable. Finally, we discuss the renormalis
ation group flow of the theory.
DTSTART:20220628T102500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Weyl covariance, second clock effect and proper time in theories
of symmetric teleparallel gravity
DESCRIPTION:Muzaffer Adak (Pamukkale University, Denizli, Turkey)\n\nWey
l covariance, second clock effect and proper time in theories of symmetr
ic teleparallel gravity\n\nWe give a new prescription of parallel transp
ort of a vector tangent to a curve which is invariant under both of a lo
cal general coordinate and a Weyl transformation. Thus, since the length
of tangent vector does not change during parallel transport along a clo
sed curve in spacetimes with non-metricity, a second clock effect does n
ot appear in general, not only for the inetgrable Weyl spacetime. We hav
e specially motivated the problem from the point of view of symmetric te
leparallel (or Minkowski-Weyl) geometry. We also conclude that as long a
s nature respects Lorentz symmetry and Weyl symmetry, one can only devel
op alternative gravity models in the symmetric teleparallel spacetime (Q
≠0,T=0,R=0) or the most general non-Riemannian spacetime (Q≠0,T≠0,
R≠0).
DTSTART:20220628T102500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Preheating in Palatini R^2 gravity
DESCRIPTION:Hardi Veermäe (National Institute of Chemical Physics and B
iophysics, Tallinn, Estonia)\n\nPreheating in Palatini R^2 gravity\n\nIn
the Palatini formalism with an R^2 term, inflation potentials will be f
lattened to form a plateau in the Einstein frame. In such models, the in
flaton field can repeatedly return to this plateau after inflation. This
results in an active tachyonic instability which effectively fragments
the inflaton condensate in less than an e-fold. We will discuss tachyoni
c preheating in Palatini R^2 gravity and in the family of plateau models
in general.
DTSTART:20220628T105000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Teleparallel Newton–Cartan gravity
DESCRIPTION:Philip Schwartz (Leibniz University Hannover, Hannover, Germ
any)\n\nTeleparallel Newton–Cartan gravity\n\nWe discuss a teleparalle
l version of Newton–Cartan gravity. This theory arises as a formal lar
ge-speed-of-light limit of the teleparallel equivalent of general relati
vity (TEGR). Thus, it provides a geometric (‘covariant’) formulation
of the Newtonian limit of TEGR, analogous to standard Newton–Cartan g
ravity being the geometric formulation of the Newtonian limit of general
relativity. We show how by a certain gauge-fixing the standard formulat
ion of Newtonian gravity can be recovered.
DTSTART:20220628T105000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Palatini Inflation
DESCRIPTION:Alexandros Karam (National Institute of Chemical Physics and
Biophysics, Tallinn, Estonia)\n\nPalatini Inflation\n\nWe present vario
us aspects of modified gravity inflationary scenarios when studied in th
e Palatini formalism.
DTSTART:20220628T111500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Metric-affine Finslerian gravity
DESCRIPTION:Fidel Fernández Villaseñor (University of Granada, Granada
, Spain)\n\nMetric-affine Finslerian gravity\n\nOver the last years, the
re has been an increasing interest and amount of results in alternative
theories of gravitation based on (Lorentz-)Finsler geometry. An importan
t achievement has been an equation obtainable by applying the metric var
iation to a geometric functional [1,2]. In this presentation, based upon
[3], we apply the Palatini formalism to the same Finslerian action. We
also clarify the structure of the solutions with torsion, extending the
classical case [4]. Then, assuming certain regularity at the lightlike d
irections, we obtain results which provide: A) The uniqueness of the tor
sion-free (nonlinear) connection, and B) The equivalence of the vacuum e
quation with the vanishing of the Finslerian Ricci scalar of such connec
tion.\n\nReferences:\n\n[1] C. Pfeifer and M. R. Wohlfart: _Finsler geom
etric extension of Einstein gravity_. Phys. Rev. D (Vol.85, No.6), 2012
.\n\n[2] M. Hohmann, C. Pfeifer and N. Voicu: _Finsler gravity action fr
om variational completion_. Phys. Rev. D 100, 064035 (2019).\n\n[3] M.
Á. Javaloyes, M. Sánchez and F. F. Villaseñor: _The Einstein-Hilbert-
Palatini formalism in pseudo-Finsler geometry_. ArXiv e-prints, arXiv:21
08.03197v2 [math.DG] (2021).\n\n[4] A. N. Bernal et al.: _On the (non-)u
niqueness of the Levi-Civita solution in the Einstein-Hilbert-Palatini f
ormalism_. Phys.Lett. B768 (2017) 280-287.
DTSTART:20220628T111500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-14-40-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220628T114000Z
DURATION:PT20M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:The slow-roll approximation: accurate enough to estimate differe
nt models of inflation?
DESCRIPTION:Margus Saal (University of Tartu, Tartu, Estonia)\n\nThe slo
w-roll approximation: accurate enough to estimate different models of in
flation?\n\nThe spectral index of scalar perturbation n and the ratio of
tensor-to-scalar perturbation r are often used to estimate the consiste
ncy of inflation models with the observed results. Extending the theory
of gravity to the scalar-tensor type theory, we show in the presentation
how very different models can give the same values for n and r. This su
ggests that these quantities may not be sufficient to determine whether
or not the model is consistent with the observations. We analyze this pr
oblem and offer solutions for what and how the model should be further e
valuated.
DTSTART:20220628T120000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Energy-momentum tensor: Noether vs Hilbert.
DESCRIPTION:Yakov Itin (Jerusalem College of Technology, Jerusalem, Isra
el)\n\nEnergy-momentum tensor: Noether vs Hilbert.\n\nIn this paper, the
relationship between two basic definitions of the energy-momentum tenso
r in field theory is discussed. Hilbert’s definition is based on the v
ariation derivative of the Lagrangian with respect to the metric tensor.
By definition, the resulting tensor is symmetric. The conservation of t
his tensor, on the other hand, requires the use of field equations. Noet
her’s definition is based on the symmetry of the Lagrangian with respe
ct to the diffeomorphism invariance. This tensor is not symmetric, but i
t can be symmetrized with the use of the Belinfante-Rosenfeld procedure.
The conservation of this tensor is self-evident from its definition. No
ether’s tensor vanishes on shell modulo a divergence of an arbitrary s
uperpotential. For most essential applications, such as Yang-Mills model
s, two tensors become equal despite having extremely different features.
Moreover, they provide meaningful (and measurable) conserved quantities
. In this study, we show that in some natural field models the tensors a
re actually equivalent. Our analysis is based on a teleparallel space-ti
me and differential-form representation. We examine the examples of the
free p-form gauge field theory, the GR in the coframe representation, an
d the metric-free electrodynamics.
DTSTART:20220628T120000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Slow-roll inflation in Palatini F(R) gravity
DESCRIPTION:Christian Dioguardi (National Institute of Chemical Physics
and Biophysics, Harju maakond, Tallinn, Estonia)\n\nSlow-roll inflation
in Palatini F(R) gravity\n\nWe study single field slow-roll inflation in
the presence of F(R) gravity in the Palatini formulation. In contrast t
o metric F(R), when rewritten in terms of an auxiliary field and moved t
o the Einstein frame, Palatini F(R) does not develop a new dynamical deg
ree of freedom. However, it is not possible to solve analytically the co
nstraint equation of the auxiliary field for a general F(R). We propose
a method that allows us to circumvent this issue and compute the inflati
onary observables. We apply this method to test scenarios of the form F(
R) = R + αR^(n) and find that, as in the previously known n =
2 case, a large α suppresses the tensor-to-scalar ratio r. We also f
ind that models with F(R) increasing faster than R² for large R suffer
from numerous problems, with possible implications on the theoretically
allowed UV behaviour of such Palatini models.
DTSTART:20220628T122500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:On conservation laws in STEGR
DESCRIPTION:Elena Emtsova (Lomonosov Moscow State university, Sternberg
Astronomical Institute, Moscow, Russia)\n\nOn conservation laws in STEGR
\n\nWe derive conservation laws in STEGR with direct application of Noet
her’s theorem. This approach allows to construct covariant conserved c
urrents, corresponding superpotentials and invariant charges. By calcula
ting currents, one can obtain local characteristics of gravitational fie
ld like energy density. Surface integration of superpotentials gives cha
rges which correspond to global quantities of the system like mass, mome
ntum, etc. To test our results for the obtained currents and superpotent
ials, we calculate the energy density measured by freely falling observe
r in the simple solutions (Schwartzchild black hole, FRLW) and total mas
s of the Schwartzchild black hole. We find ambiguities in obtaining the
connection, which explicitly affect the values of conserved quantities,
and discuss a constructive solution to this problem.
DTSTART:20220628T122500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Inflation in Hybrid Metric Palatini Gravity
DESCRIPTION:Haidar Sheikhahmadi (North West University, Mafikeng, South
Africa)\n\nInflation in Hybrid Metric Palatini Gravity\n\nWe consider an
inflationary scenario in the framework of the Hybrid Metric Palatini Gr
avity in which a supplementary term, containing a Palatini type correcti
on is added to the standard GR action. This configuration can be reformu
lated into the equivalent form of a scalar-tensor theory, in which a low
mass scalar field can explain the observed gravitational phenomenology,
by generating long-range forces that pass all the local tests without i
nvoking any kind of screening mechanism, chameleon scenario for instance
. We look over the possibility that this effective scalar field may gene
rate the matter content of the early Universe.
DTSTART:20220628T125000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-15-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Energy and entropy in the Geometrical Trinity of gravity
DESCRIPTION:Débora Aguiar Gomes (Federal University of Ceará, Fortalez
a, Brazil)\n\nEnergy and entropy in the Geometrical Trinity of gravity\n
\nAll energy is gravitational energy. That is the consequence of the equ
ivalence principle, according to which gravity is the universal interact
ion. The physical charges of this interaction have remained undisclosed,
but the Advent of the Geometrical Trinity opened a new approach to this
foundational problem. Here it is shown to provide a background-independ
ent unification of the previous, noncovariant approaches of Bergmann-Tho
mson, Cooperstock, Einstein, von Freud, Landau-Lifshitz, Papapetrou and
Weinberg. First, the Noether currents are derived for a generic Palatini
theory of gravity coupled with generic matter fields, and then the cano
nical i.e. the unique charges are robustly derived and analysed, partic
ularly in the metric teleparallel and the symmetric teleparallel version
s of General Relativity. These results, and their application to black h
oles and gravitational waves, are new.
DTSTART:20220628T125000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-16-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220628T131500Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-16-30-00
DTSTAMP:20241004T184040Z
SUMMARY:Discussion (Metric-Affine Gravity: geometry vs matter interpreta
tion)
DESCRIPTION:Discussion leader: Adrià Delhom I Latorre
DTSTART:20220628T133000Z
DURATION:PT50M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-28-18-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Public Talk - Rodrigues
DESCRIPTION:Prof. Davi Rodrigues will speak at the historic Tartu Old O
bservatory on the topic “Why do galaxies rotate?”
DTSTART:20220628T151500Z
DURATION:PT60M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-09-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Hamiltonian approach to entropy in Poincare gauge theory
DESCRIPTION:Branislav Cvetkovic (Institute of physics, University of Bel
grade, Belgrade, Serbia)\n\nHamiltonian approach to entropy in Poincare
gauge theory\n\nThe canonical generator G of local symmetries in Poincar
e gauge theory is constructed as an integral over a spatial section Σ o
f spacetime. Its regularity (differentiability) on the phase space is en
sured by adding a suitable surface term, an integral over the boundary o
f at infinity, which represents the asymptotic canonical charge. For bla
ck hole solutions, Σ has two boundaries, one at infinity and the other
at horizon. It is shown that the canonical charge at horizon defines ent
ropy, whereas the regularity of G implies the first law of black hole th
ermodynamics. The approach is tested for several black hole types.
DTSTART:20220629T061500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-10-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffee Break / Poster Viewing
DESCRIPTION:
DTSTART:20220629T071500Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-10-30-00
DTSTAMP:20241004T184040Z
SUMMARY:ΛCDM theory of cosmology
DESCRIPTION:Tomi Koivisto (University of Tartu, Tallinn, Estland)\n\nΛC
DM theory of cosmology\n\nThe constants Λ and the CDM in the standard m
odel of cosmology arise as integration constants in the derivation of Ei
nstein’s equations from the gauge theory of the Lorentz group.
DTSTART:20220629T073000Z
DURATION:PT30M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-11-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Conformal Invariant Metric-Affine Gravity Theories
DESCRIPTION:Emanuele Orazi (Federal University of Rio Grande do Norte, N
atal, Brasil)\n\nConformal Invariant Metric-Affine Gravity Theories\n\nA
recent revival of the link between conformal symmetry and projective in
variance in the framework of metric-affine gravity theories motivated a
systematic study of a general strategy to build a conformal version of a
ny modified gravity. In this oral presentation will be clarified the und
erlying gauge symmetry associated to conformal invariance and its theore
tical and phenomenological implications deriving from the explicit solut
ions of field equations in the metric affine formalism.
DTSTART:20220629T080000Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-11-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Symmetries in gauge theories of gravity with and without nondyna
mical fields
DESCRIPTION:Yuri Bonder (Universidad Nacional Autonoma de Mexico, Mexico
City, Mexico)\n\nSymmetries in gauge theories of gravity with and witho
ut nondynamical fields\n\nI will present a transparent and concise metho
d to write generic gauge theory, including gravity gauge theories, and e
xtract the corresponding symmetries from the Lagrangian equations of mot
ion. This method can be applied to theories where the symmetries are bro
ken by the presence of nondynamical fields. As an example, I will discus
s unimodular gravity in the first order formalism, where invariance unde
r diffeomorphisms is partially broken. Still, the method can be used to
read off the remaining symmetries. Remarkably, the symmetry algebra was
calculated and it is possible to verify that it is has the expected prop
erties.
DTSTART:20220629T082500Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-11-50-00
DTSTAMP:20241004T184040Z
SUMMARY:On the differences between General Relativity and Unimodular Gra
vity
DESCRIPTION:Gerardo García-Moreno (Instituto de Astrofísica de Andaluc
ía, Granada, Spain)\n\nOn the differences between General Relativity an
d Unimodular Gravity\n\nWeyl Transverse-Diffeomorphisms (WTDiff) gravity
is a theory so closely related to General Relativity (GR) that one can
wonder to what extent they are really different. Unimodular gravity can
be thought as a simple gauge fixing of WTDiff and hence completely equiv
alent to it. WTDiff and GR are based on two different gauge symmetries:
WTDiff is based on Transverse Diffeomorphisms and Weyl-rescalings of an
auxiliary metric, whereas GR is based on the full group of diffeomorphis
ms. The formal difference appears due to the existence of a fiduciary ba
ckground structure, a fixed volume form, in WTDiff theories.\n\nIn this
talk I will present an overview as complete as possible of all the situa
tions and regimes in which one might suspect that some differences betwe
en these two theories might arise. This overview contains analysis in th
e classical, semiclassical and quantum regimes.
DTSTART:20220629T085000Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-12-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Lunch
DESCRIPTION:
DTSTART:20220629T091500Z
DURATION:PT75M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-29-13-30-00
DTSTAMP:20241004T184040Z
SUMMARY:Excursion
DESCRIPTION:See Social Program
DTSTART:20220629T103000Z
DURATION:PT480M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-09-15-00
DTSTAMP:20241004T184040Z
SUMMARY:The harzards in Affinesia: Quicksands and sweet spots
DESCRIPTION:Jose Beltran Jimenez (Universidad de Salamanca, Salamanca, S
pain)\n\nThe harzards in Affinesia: Quicksands and sweet spots\n\nThe eq
uivalence principle naturally provides gravity with a geometrical charac
ter, thus making the metric-affine framework be a natural land for gravi
ty theories. However, the precise geometry we employ admits a certain fl
exibility and, in particular, Einstein’s gravity can be equivalently a
scribed to the three independent objects that characterise a connection,
i.e., curvature, torsion and non-metricity. After reviewing these three
alternative descriptions of gravity, I will uncover how pathologies gen
erally arise beyond these GR equivalents and illustrate with some exampl
es how to get around them.
DTSTART:20220630T061500Z
DURATION:PT60M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-10-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffee Break / Poster Viewing
DESCRIPTION:
DTSTART:20220630T071500Z
DURATION:PT30M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-10-45-00
DTSTAMP:20241004T184040Z
SUMMARY:General cosmologies and their perturbations in teleparallel grav
ity
DESCRIPTION:Manuel Hohmann (University of Tartu, Tartu, Estonia)\n\nGene
ral cosmologies and their perturbations in teleparallel gravity\n\nWithi
n the framework of teleparallel gravity, a flat affine connection is use
d as a dynamical field in addition to the metric tensor. Depending on th
e class of theories, this connection may further be restricted by imposi
ng either vanishing torsion or vanishing nonmetricity. In the field of c
osmology, most commonly a particular, simple, homogeneous and isotropic
connection has been chosen, and its background dynamics and perturbation
s have been studied for different theories. While this does lead to a se
t of cosmological dynamical equations, it is far from being the most gen
eral cosmological dynamics in teleparallel gravity. This presentation gi
ves a complete classification of all homogeneous and isotropic teleparal
lel geometries (general, metric and symmetric), as well as their perturb
ations. For the latter, gauge transformations and gauge invariant quanti
ties are presented. It is shown that:\n\n- general teleparallel gravit
y admits two spatially curved branches with three spatially flat limits,
\n- symmetric teleparallel gravity admits one spatially curved branch
with three spatially flat limits,\n- metric teleparallel gravity admit
s two spatially curved branches with one spatially flat limit,\n\nand th
at the two latter cases arise as limits of the first.
DTSTART:20220630T074500Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-11-10-00
DTSTAMP:20241004T184040Z
SUMMARY:Traditional and Novel approaches to model selection in f(T) grav
ity using recent observational cosmology
DESCRIPTION:Jackson Said (Institute of Space Sciences and Astronomy, Msi
da, Malta)\n\nTraditional and Novel approaches to model selection in f(T
) gravity using recent observational cosmology\n\nTeleparallel gravity o
ffers numerous possible classes of theories and arbitrary models in each
class. One such example is f(T) gravity where any functional form of th
e torsion scalar is included. The problem of reducing the space of viabl
e functions has led to several recent interesting avenues of research. T
raditionally, models in theories like f(T) gravity would be chosen to me
et specific observational or theoretical conditions, which would then be
constrained against various observations using Bayesian methods. Recent
works in the literature have proposed the use of machine learning techn
iques to reverse the way models are selected in theories like f(T) gravi
ty so that observational data can be used to define the functional form
of the model. In this talk, I will cover some of these new approaches an
d discuss how they compare with previous methods.
DTSTART:20220630T081000Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-11-35-00
DTSTAMP:20241004T184040Z
SUMMARY:Transferring the troubles from torsion to non-metricity
DESCRIPTION:Alexey Golovnev (British University in Egypt, El Sherouk, Ca
iro, Egypt)\n\nTransferring the troubles from torsion to non-metricity\n
\nIt is a very interesting field of modified gravity research now, const
ructing modifications starting from alternative geometrical foundations.
It gives very exciting new angles to look at general relativity, in par
ticular because no simple modifications of this sort appear to be health
y. I will briefly review the foundational issues of modified teleparalle
l gravity, then discuss modified symmetric teleparallel models, and comp
are the two approaches.
DTSTART:20220630T083500Z
DURATION:PT25M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-12-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Lunch
DESCRIPTION:
DTSTART:20220630T090000Z
DURATION:PT60M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Lorentz symmetries in teleparallel theories of gravity
DESCRIPTION:Daniel Blixt (Scuola Superiore Merdionale, Naples, Italy)\n\
nLorentz symmetries in teleparallel theories of gravity\n\nTeleparallel
gravity is a peculiar limit in the metric affine frameworks of gravity w
here curvature is taken to zero and still a classically equivalent to ge
neral relativity can be found. In its original formulation teleparallel
gravity breaks Lorentz invariance at minimum at the boundary and in its
most generic case fully. Later there was a realization that a spin conne
ction can be introduced for which Lorentz transformations of the couple
tetrad and spin connection leaves the action invariant. This is referred
to as the covariant formulation of teleparallel gravity. In this talk I
will give deeper insights of Lorentz symmetries in teleparallel theorie
s of gravity referring to both a simple observation as well as to the Ha
miltonian analysis and highlight the relation to physical degrees of fre
edom.
DTSTART:20220630T100000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Reconstruction of Matter Bounce Cosmology in symmetric teleparal
lel gravity
DESCRIPTION:Bivudutta Mishra (BITS-Pilani, Hyderabad Campus, Hyderabad,
India)\n\nReconstruction of Matter Bounce Cosmology in symmetric telepar
allel gravity\n\nIn this paper, we have constructed the cosmological mod
el of the universe that shows the bouncing scenario. We have obtained sp
ecific form of the function f(Q) that shows the bouncing behavior at the
backdrop of homogeneous and isotropic space-time, Q being the nonmetric
ity. The dynamics of the model has been studied with the help of critica
l points and the stability behavior has been discussed.
DTSTART:20220630T100000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Canonical structure of symmetric teleparallel and f(Q) gravity
DESCRIPTION:Maria-Jose Guzman (University of Tartu, Tartu, Estonia)\n\nC
anonical structure of symmetric teleparallel and f(Q) gravity\n\nModifie
d gravities based on non-metricity of spacetime have gained an increased
attention in recent years. In particular, f(Q) gravity models come as t
he simplest generalization of the symmetric teleparallel equivalent of g
eneral relativity, and are intensively used in cosmological applications
. However, the question of the number of physical degrees of freedom and
their behavior is not clear. In this talk we will review the literature
and recent progress on the Hamiltonian formalism for symmetric telepara
llel and f(Q) gravity, compare to the controversial case of f(T) gravity
, and derive conclusions that might be of help for future research.
DTSTART:20220630T102500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Rip cosmological models in extended symmetric teleparallel gravi
ty
DESCRIPTION:Laxmipriya Pati (BITS Pilani, Hyderabad, India)\n\nRip cosmo
logical models in extended symmetric teleparallel gravity\n\nIn this wor
k, we have investigated some rip cosmological models in an extended symm
etric teleparallel gravity theory. We consider the form f(Q, T) = aQ^m+b
T in the Einstein–Hilbert action and expressed the field equations and
the dynamical parameters in terms of the non-metricity ‘Q’. Three r
ip models such as Little Rip, Big Rip and Pseudo Rip are presented. The
energy conditions and the cosmographic parameters are derived and analys
ed for all these models.
DTSTART:20220630T102500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Remnant symmetries in f(T)-like models: lessons from 2D
DESCRIPTION:Franco Fiorini (Insituto Balseiro & Conicet, S. C. de Barilo
che, Argentina)\n\nRemnant symmetries in f(T)-like models: lessons from
2D\n\nBy constructing two-dimensional, non-local Lorentz invariant gravi
tational actions based on the torsion tensor, we discuss the physical me
aning of the remnant symmetries associated with the near-horizon geometr
y experienced by a radial observer in Schwarzschild spacetime. These sym
metries, which represent special or privileged diads, acquire the form o
f uniformly accelerated (Rindler) observers whose constant acceleration
is proportional to the black hole mass M.
DTSTART:20220630T105000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-13-50-00
DTSTAMP:20241004T184040Z
SUMMARY:Constraining effective equation of state in f (Q, T) gravity
DESCRIPTION:Simran Arora (Birla Institute of Technology and Science-Pila
ni, Hyderabad Campus, Hyderabad, India)\n\nConstraining effective equati
on of state in f (Q, T) gravity\n\nNew high-precision observations are n
ow possible to constrain different gravity theories. To examine the acce
lerated expansion of the Universe, we used the newly proposed f(Q,T) gra
vity, where Q is the non-metricity, and T is the trace of the energy-mom
entum tensor. The investigation is carried out using a parameterized eff
ective equation of state with two parameters, m and n. We have also con
sidered the linear form of f(Q,T) = Q + b T, where b is constant. By con
straining the model with the recently published 1048 Pantheon sample, we
were able to find the best fitting values for the parameters b, m, and
n. The model appears to be in good agreement with the observations. Fin
ally, we analyzed the behavior of the deceleration parameter and equatio
n of state parameter. The results support the feasibility of f(Q,T) as a
promising theory of gravity, illuminating a new direction towards expla
ining the Universe’s dark sector.
DTSTART:20220630T105000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Teleparallel Gravities as a gauge theories: TEGR and STGR, a wor
k in progress
DESCRIPTION:Morgan Le Delliou (Lanzhou University, Lanzhou, China)\n\nTe
leparallel Gravities as a gauge theories: TEGR and STGR, a work in progr
ess\n\nInitiated with a question on the mathematical nature of the conne
ction in the so-called “translations gauge theory” formulation of Te
leparallel Equivalent to General Relativity (TEGR) Theory, our explorati
ons led us to consider a novel approach using a Cartan connection. The m
athematically admitted underlying structure of a gauge theory for a symm
etry group G relies on a principal G-bundle on which is chosen a connect
ion (the gauge field). The bundle formalism with connection allows to di
stinguish in the structure of TEGR as “translations gauge theory” th
at the algebra of translations is indeed necessary to build the torsion,
which could resemble the field strength of that gravity. However, the c
orresponding field clearly does not present the structure of a connectio
n. Nevertheless, the translation field can be integrated in a Cartan con
nection, as shown in our approach, which allows to keep the interpretati
on of the translation field as related to a connection. The coupling to
matter can be performed thanks to a Cartan connection and a theorem by S
harpe to obtain a consistent and complete description of TEGR that confi
rms its difference with the usual structures of gauge theories. The appr
oach to STGR involves a closer examination of bundle reduction and solde
ring form that appear to mark the specificity of gravity. Although the f
rame field remains the best candidate for what could be recognised as a
gauge field, the introduction of a distinct soldering form through a bun
dle reduction giving birth to the metric on the base leads to a specific
structure. To bring such a framework closer to a theory with a connecti
on will require more investigations.
DTSTART:20220630T111500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-14-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Dynamical features of f(T, B) cosmology
DESCRIPTION:Siddheshwar Kadam (BITS-Pilani, Hyderabad, India)\n\nDynamic
al features of f(T, B) cosmology\n\nIn this paper, we have explored th
e field equations of f(T, B) gravity and determined the dynamical para
meters with the hyperbolic function of the Hubble parameter. The acceler
ating behavior has been observed and the behavior of the equation of sta
te parameter indicates the ΛCDM model at a late time. The role of model
parameters in assessing accelerating behavior has been emphasized. The
stability of the model is analyzed by using scalar perturbation.
DTSTART:20220630T111500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-14-40-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220630T114000Z
DURATION:PT20M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Scalarized Black Holes in Teleparallel Gravity
DESCRIPTION:Ludovic Ducobu (University of Mons, Mons, Belgium)\n\nScalar
ized Black Holes in Teleparallel Gravity\n\nIf General Relativity [GR] o
ffers an extremely successful framework to describe the gravitational in
teraction, whose achievements range from the solar system to the cosmolo
gical scale, the necessity to question the framework of GR is clear at b
oth the experimental and theoretical levels. Since not all of the curren
t puzzles can be purely reduced to quantum correction problems, this mot
ivates the study of alternative theories of gravitation already at the c
lassical level.\n\nAmong the many possible directions one can follow, an
interesting one consists in the addition of new degrees of freedom in t
he theory (in addition to the spacetime metric). In this respect, the si
mplest candidate is a scalar field. Alternative theories of gravity incl
uding a scalar field have attracted a lot of attention in the past decad
e. This is especially true for Horndeski gravity; the most general scala
r-tensor theory of gravity in 4D, based on the same geometrical framewor
k as GR, including a real scalar field and presenting second order field
equations.\n\nThe aim of this talk will be to introduce recent results
of our research in the context of teleparallel theories of gravity exten
ded by scalar fields. I will start by a short synopsis of the main featu
res of teleparallel theories of gravity compared to metric based theorie
s (especially GR). I will then discuss recent results regarding hairy bl
ack holes for some teleparallel theories of gravity endowed with a non-m
inimally coupled real scalar field.\n\nIf time permits, I will comment o
n how one could possibly extend results obtained for metric based scalar
-tensor theories of gravity using the framework of teleparallel gravity.
DTSTART:20220630T120000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Inhomogeneous solutions in f(T, B) gravity
DESCRIPTION:Armando Aram Reyes Aguilar (Nuclear Sciences Institute, Mexi
co city, Mexico)\n\nInhomogeneous solutions in f(T, B) gravity\n\nIn t
his paper, we explore the possibility to find exact solutions for Telepa
rallel Gravity (TG) of the type of spherically symmetric Lemaître-Tolma
n-Bondi (LTB) dust models. We apply to the LTB metric the formalism of T
G in its extension to f(T, B) models, which can be seen as the analogo
us from the Schwarzschild solution in General Relativity. An exact LTB s
olution is obtained which is compatible with a specific f(T, B) model
whose observational constraints are cosmologically viable in a standard
spatially flat Robertson-Walker geometry.
DTSTART:20220630T120000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Black hole solutions in scalar-tensor symmetric teleparallel gra
vity
DESCRIPTION:Joosep Lember (University of Tartu, Tartu, Estonia)\n\nBlack
hole solutions in scalar-tensor symmetric teleparallel gravity\n\nSymme
tric teleparallel gravity is constructed with a nonzero nonmetricity ten
sor while both torsion and curvature are vanishing. In this framework, w
e find exact scalarised spherically symmetric static solutions in scalar
-tensor theories built with a nonminimal coupling between the nonmetrici
ty scalar and a scalar field. It turns out that the Bocharova-Bronnikov-
Melnikov-Bekenstein solution has a symmetric teleparallel analogue (in a
ddition to the recently found metric teleparallel analogue), while some
other of these solutions describe scalarised black hole configurations t
hat are not known in the Riemannian or metric teleparallel scalar-tensor
case. To aid the analysis we also derive no-hair theorems for the theor
y. Since the symmetric teleparallel scalar-tensor models also include f(
Q) gravity, we shortly discuss this case and further prove a theorem whi
ch says that by imposing that the metric functions are the reciprocal of
each other (g_(rr) = 1/g_(tt)), the f(Q) gravity theory reduces to
the symmetric teleparallel equivalent of general relativity (plus a cosm
ological constant), and the metric takes the (Anti)de-Sitter-Schwarzschi
ld form.
DTSTART:20220630T122500Z
DURATION:PT20M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Non-exotic wormholes in f(R, T) gravity
DESCRIPTION:Paul Martin Kull (University of Tartu, Tartu, Estonia)\n\nNo
n-exotic wormholes in f(R, T) gravity\n\nIn this work, stable traversa
ble wormhole models that satisfy at least the null energy condition (NEC
) everywhere are developed in the geometric representation of f(R, T)
gravity. The NEC is satisfied both everywhere in the wormhole spacetime
and by using the thin-shell formalism to match the wormhole spacetime wi
th an exterior vacuum spacetime. In the first case, conditions are deter
mined for the particular forms of the shape and redshift functions b(r)
and ζ(r) considered that guarantee that the resulting spacetime satisfi
es at least the NEC everywhere. In the second case, after deriving the j
unction conditions for the particular form of the theory used, one finds
that the radius r_(Σ) of the thin-shell is not restricted to single va
lues for some values of the throat radius r₀. This allows one to choos
e r_(Σ) and r₀ such that the weak energy condition can also be satisf
ied everywhere.
DTSTART:20220630T122500Z
DURATION:PT20M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Spherically symmetric static spacetime in the coincident gauge o
f symmetric teleparallel gravity
DESCRIPTION:Laur Järv (University of Tartu, Tartu, Estonia)\n\nSpherica
lly symmetric static spacetime in the coincident gauge of symmetric tele
parallel gravity\n\nIn the context of symmetric teleparallel gravity the
coincident gauge denotes a coordinate system where the affine connectio
n vanishes globally and the covariant derivatives reduce to partial deri
vatives. Despite the allure for computational ease, explicit examples of
this are hard to come by. In the talk we consider general metric and af
fine connection which both are spherically symmetric and static, and tra
nsform this configuration into the coincident gauge. We conclude with a
comparison to the Weitzenböck gauge in metric teleparallelism, and rema
rks about the notion of ‘purely inertial connection’.
DTSTART:20220630T124500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-15-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Main Results and Current Progress within the Scale Invariant Vac
uum Paradigm
DESCRIPTION:Vesselin Gueorguiev (Institute for Advanced Physical Studies
, Sofia, Bulgaria)\n\nMain Results and Current Progress within the Scale
Invariant Vacuum Paradigm\n\nA review of the Scale Invariant Vacuum (SI
V) idea will be presented as related to Weyl Integrable Geometry [1]. Th
e main results related to SIV and inflation [2], the growth of the densi
ty fluctuations [3], and the application of the SIV to scale-invariant d
ynamics of Galaxies, MOND, Dark Matter, and the Dwarf Spheroidals [4] wi
ll be highlighted.\n\n[1] Gueorguiev, V. G., Maeder, A., The Scale Invar
iant Vacuum Paradigm: Main Results and Current Progress. Universe 2022,
8 (4) 213; DOI:10.3390/universe8040213 [gr-qc/2202.08412].\n\n[2] Maeder
, A., Gueorguiev, V. G., Scale invariance, horizons, and inflation. MNRA
S 504, 4005 (2021) [gr-qc/2104.09314].\n\n[3] Maeder, A., Gueorguiev, V.
, G., The growth of the density fluctuations in the scale-invariant vacu
um theory. Phys. Dark Univ. 25, 100315 (2019) [astro-ph.CO/1811.03495]\n
\n[4] Maeder, A.; Gueorguiev, V.G. Scale-invariant dynamics of galaxies,
MOND, dark matter, and the dwarf spheroidals. MNRAS 492, 2698 (2019) [g
r-qc/2001.04978]
DTSTART:20220630T124500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-16-10-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffe Break
DESCRIPTION:
DTSTART:20220630T131000Z
DURATION:PT15M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-16-25-00
DTSTAMP:20241004T184040Z
SUMMARY:Discussion (Teleparallel Gravity: viable or not)
DESCRIPTION:Discussion leader: Christian Pfeifer
DTSTART:20220630T132500Z
DURATION:PT55M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-06-30-19-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Conference dinner
DESCRIPTION:See Social Program
DTSTART:20220630T160000Z
DURATION:PT120M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-09-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Testing modified gravity rotation curves with the Normalized Add
itional Velocity method
DESCRIPTION:Davi Rodrigues (Federal University of Espirito Santo (UFES),
Vitória, Brazil)\n\nTesting modified gravity rotation curves with the
Normalized Additional Velocity method\n\nI will introduce the Normalized
Additional Velocity (NAV) method and show how to apply it, with focus o
n modified gravity (although it can also be useful for dark matter profi
les). The method will be illustrated with several models, including f(R)
Palatini, Eddington-inspired-Born-Infeld (EiBI), MOND and others. It is
a complementary and fast approach to study galaxy rotation curves (RCs)
directly from the sample distribution, instead of first performing seve
ral individual RC fits. It does not cover all the RC properties, but it
focuses on the shape of the non-Newtonian contribution for a given sampl
e (we use 122 SPARC galaxies). A relevant advantage, when applying the m
ethod to modified gravity models, is that for several models it is possi
ble to use approximations that circumvent the need for solving modified
Poisson equations for each one of the galaxies. Among other results, we
show that f(R) Palatini and EiBI gravities cannot be used to replace dar
k matter in galaxies, while MOND has reasonable results, although with a
n issue.\n\nBased on https://arxiv.org/abs/2204.03762 and more recent de
velopments.
DTSTART:20220701T061500Z
DURATION:PT30M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-09-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Tracing torsional gravity in the early universe: primordial blac
k holes and gravitational waves
DESCRIPTION:Emmanuel Saridakis (National Observatory of Athens, Athens,
Greece)\n\nTracing torsional gravity in the early universe: primordial b
lack holes and gravitational waves\n\nThere is a huge variety of gravita
tional modifications constructed for theoretical reasons, namely to alle
viate the renormalizability issues of General Relativity, as well as for
cosmological reasons, namely to successfully describe the Universe evol
ution and alleviate possible observational tensions. It is time to start
using the rich observational datasets of increasing accuracy in order t
o distinguish between them. We search for signatures and smoking guns of
torsional modified gravity in late- and early-time cosmological observa
tions, focusing on gravitational waves and primordial black holes.
DTSTART:20220701T064500Z
DURATION:PT30M
LOCATION:A106
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-10-15-00
DTSTAMP:20241004T184040Z
SUMMARY:Closing remarks
DESCRIPTION:We end the last parallel session with a few comments on prev
ious and possible future meetings.
DTSTART:20220701T071500Z
DURATION:PT5M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-10-20-00
DTSTAMP:20241004T184040Z
SUMMARY:Coffee Break / Poster Viewing
DESCRIPTION:
DTSTART:20220701T072000Z
DURATION:PT25M
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-10-45-00
DTSTAMP:20241004T184040Z
SUMMARY:A new generic and structurally stable cosmological model without
singularity
DESCRIPTION:Orest Hrycyna (National Centre for Nuclear Research, Warszaw
a, Poland)\n\nA new generic and structurally stable cosmological model w
ithout singularity\n\nDynamical systems methods are used to investigate
a cosmological model with non-minimally coupled scalar field and asympto
tically quadratic potential function. We found that for values of the no
n-minimal coupling constant parameter $\frac{3}{16}\lt\xi\lt\frac{1}{4}$
there exists an unstable asymptotic de Sitter state giving rise to non-
singular beginning of universe. The energy density associated with this
state depends on value of the non-minimal coupling constant and can be m
uch smaller than the Planck energy density. For $\xi=\frac{1}{4}$ we fou
nd that the initial state is in form of the static Einstein universe. Pr
oposed evolutional model, contrary to the seminal Starobinsky’s model,
do not depend on the specific choice of initial conditions in phase spa
ce, moreover, a small change in the model parameters do not change the e
volution thus the model is generic and structurally stable. The values o
f the non-minimal coupling constant can indicate for a new fundamental s
ymmetry in the gravitational theory. We show that Jordan frame and Einst
ein frame formulation of the theory are physically nonequivalent.
DTSTART:20220701T074500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-10-45-00
DTSTAMP:20241004T184040Z
SUMMARY:Covariant Hamilton-Jacobi Equation for the Teleparallel Equivale
nt of General Relativity
DESCRIPTION:Monika E. Pietrzyk (University of Exeter, Exeter, United Kin
gdom)\n\nCovariant Hamilton-Jacobi Equation for the Teleparallel Equival
ent of General Relativity\n\nThe covariant De Donder-Weyl Hamiltonian th
eory of the Teleparallel Equivalent of General Relativity is formulated
using the methods developed by I. Kanatchikov within his approach of pre
canonical quantization. Based on the results from the geometric Hamilton
-Jacobi theory for variational problems we derive a covariant Hamilton-J
acobi equation for TEGR which generalizes the covariant Hamilton-Jacobi
equation for General Relativity which was obtained by Th. De Donder (193
0) and P. Hoava (1991). I also comment on the problem of the relation be
tween the canonical HJ equations derived from the canonical ADM formalis
m and the covariant HJ equations derived from the De Donder-Weyl Hamilto
nian theory. The covariant HJ equation can be used for numerical simulat
ions or as a test of the classical limit of quantum TEGR, its quasiclass
ical study and Bohmian-like formulation. Based on my joint paper with C.
Barbachoux: e-Print: 2201.01295 [gr-qc].
DTSTART:20220701T074500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-11-10-00
DTSTAMP:20241004T184040Z
SUMMARY:Symmetric teleparallel f(Q) gravity with non-minimally coupled f
ermion field
DESCRIPTION:Nurgissa Myrzakulov (LN Gumilyov Eurasian National Universit
y, Nur-Sultan, Kazakhstan)\n\nSymmetric teleparallel f(Q) gravity with n
on-minimally coupled fermion field\n\nIn this work, we explore the symme
tric teleparallel f(Q) gravity, which is non-minimally coupled with the
fermion field in the Friedmann-Robertson-Walker metric. By using the Lag
range multiplier modified Friedmann equations, Dirac equations for the f
ermion field are obtained. Using the Noether symmetry method, the form o
f the coupling between gravity and matter, the self-consistent potential
, the symmetry generators, the form of f(Q) gravity, and the conserved q
uantity for this model are determined. Cosmological solutions describe t
he late-time accelerated expansion of the Universe obtained.
DTSTART:20220701T081000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-11-10-00
DTSTAMP:20241004T184040Z
SUMMARY:Towards quantum geometric trinity of gravity
DESCRIPTION:Igor Kanatchikov (Natl.Quantum Information Center, Sopot, Po
land)\n\nTowards quantum geometric trinity of gravity\n\nWe plan to pres
ent (i) a reformulation of the classical geometric trinity of gravity wh
ich allows discussing quantization of equivalent descriptions of general
relativity within a unifying framework, (ii) the covariant Hamiltonian
formulation of the trinity based on the polysymplectic formalism and the
Poisson-Gerstenhaber brackets of differential forms, and the Dirac-like
analysis of constraints, (iii) a quantum formulation of the trinity bas
ed on the quantization of the analog of Dirac brackets in the above form
alism that leads to three different covariant generalizations of the Sch
roedinger (or Wheeler-Dewitt) equation for quantum gravity. They treat s
pace-time dimensions on equal footing and describe quantum geometry in t
erms of Clifford-algebra-valued amplitudes of spin-connection (in GR) or
vielbeins (in TEGR), or metric density (in Coincident GR). We briefly d
iscuss a relation to the canonical ADM formulations and the canonical qu
antization, the emergence of the classical limit, the non-Gaussian stati
stics of quantum gravitational fluctuations in a cosmological context, a
naive estimation of the quantum gravity contribution to the cosmologica
l constant, and the scale when quantum-gravitational fluctuations “foa
m” classical space-time, which turns out to be significantly sub-Planc
kian.
DTSTART:20220701T081000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-11-35-00
DTSTAMP:20241004T184040Z
SUMMARY:Cosmological model with time varying deceleration parameter in F
(R, G) gravity
DESCRIPTION:Santosh Lohakare (BITS Pilani, Hyderabad, India)\n\nCosmolog
ical model with time varying deceleration parameter in F(R, G) gravity\n
\nIn this work, we investigate the dynamical behavior of the Universe in
the F(R, G) theory of gravity, where R and G indicate the Ricci scalar
and Gauss-Bonnet invariant, respectively. The energy conditions, cosmogr
aphic parameters, stability, and the possibility of recreating the menti
oned model using a scalar field formalism are all part of our comprehens
ive research. At late times, the model obtained here exhibits quintessen
ce-like behavior.
DTSTART:20220701T083500Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-11-35-00
DTSTAMP:20241004T184040Z
SUMMARY:On possible quantization of metric tensor and affine connection
DESCRIPTION:Abdel Nasser Tawfik (Future University in Egypt (FUE), New C
airo, Egypt)\n\nOn possible quantization of metric tensor and affine con
nection\n\nWhen the minimal length approach emerging from noncommutative
Heisenberg algebra, generalized uncertainty principle, and thereby inte
grating gravitational fields to this fundamental theory of quantum mecha
nics (QM) is thoughtfully extended to general relativity (GR), the possi
ble quantization of the fundamental tensor is suggested. This is a compl
ementary term reconciling principles of QM and GR and comprising noncomm
utative algebra together with maximal spacelike four-acceleration. That
quantization compiles with GR as curvature in relativistic eight-dimensi
onal spacetime tangent bundle, Finsler spacetime, the generalization of
the pseudo-Riemannian spacetime, is the recipe applied to derive the qua
ntized metric tensor. This dictates how the affine connection on pseudo-
Riemannian manifold is straightforwardly quantized. We have discussed th
e symmetric property of quantized metric tensor and affine connection.
DTSTART:20220701T083500Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-12-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Matter bounce scenario in the functional form of f(R) gravity
DESCRIPTION:Amarkumar Agrawal (Birla Institute of Technology and Science
, Pilani, Hyderabad Campus, India, Hyderabad, India)\n\nMatter bounce sc
enario in the functional form of f(R) gravity\n\nWe examined bouncing co
smological models in an isotropic and homogeneous space-time with the f(
R) theory of gravity. The bouncing scale factor was used to study two fu
nctional forms of f(R). Along with the cosmographic parameters, the dyna
mical parameters are calculated and analysed. Both the models’ analyse
s reveal the presence of bounce. In both models, the violation of strong
energy conditions is also shown.
DTSTART:20220701T090000Z
DURATION:PT25M
LOCATION:A101
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-12-00-00
DTSTAMP:20241004T184040Z
SUMMARY:Probing quantum gravity and non-locality through R^2-like inflat
ion
DESCRIPTION:Sravan Kumar (Tokyo Institute of Technology, Tokyo, Japan)\n
\nProbing quantum gravity and non-locality through R^2-like inflation\n\
nCosmic inflation is an important paradigm of the early Universe which i
s so far developed in two equivalent ways, either by geometrical modific
ation of Einstein’s general relativity (GR) or by introducing new form
s of matter beyond the standard model of particle physics. Starobinsky
’s R+R^2 inflation based on a geometric modification of GR is one of t
he most observationally favorable models of cosmic inflation based on a
geometric modification of GR. In this talk, I will discuss in detail the
fundamental motivations for Starobinsky inflation and present how certa
in logical steps in the view of its UV completion lead to the emergence
of a gravity theory that is non-local in nature. Then I will establish h
ow one can perform studies of the early Universe in the context of non-l
ocal gravity and what are the observational consequences in the scope of
future CMB and gravitational waves. I will discuss in detail how non-lo
cal R^2-like inflation can be observationally distinguishable from the l
ocal effective field theories of inflation. Finally, I will comment on t
he prospects of non-local gravity as a promising candidate for quantum g
ravity.
DTSTART:20220701T090000Z
DURATION:PT25M
LOCATION:A102
END:VEVENT
BEGIN:VEVENT
UID:geomgrav-2022-07-01-12-25-00
DTSTAMP:20241004T184040Z
SUMMARY:The cooling process of brown dwarfs in Horndeski theory of gravi
ty
DESCRIPTION:Kärt Soieva (University of Tartu, Tartu, Estonia)\n\nThe co
oling process of brown dwarfs in Horndeski theory of gravity\n\nIn the p
resentation the cooling process of brown dwarf stars in the framework of
DHOST theories will be discussed. The analytical model and its numerica
l solutions are showcased.
DTSTART:20220701T092500Z
DURATION:PT20M
LOCATION:A101
END:VEVENT
END:VCALENDAR