59. Winter School of Theoretical Physics and third COST Action CA18108 Training School "Gravity -- Classical, Quantum and Phenomenology"

Session

Students' talks

13 Feb 2023, 16:30

3. Probing gravitational theories via primordial black holes

Charalampos Tzerefos

13/02/2023, 16:30

One of the common prepositions in theoretical physics is that modified gravity theories capture quantum gravity corrections to general relativity at a phenomenological level. A recent new window to probe these corrections presented itself in the form of studying the scalar induced GWs which are produced by primordial black holes (PBHs) through second-order gravitational effects. In my talk, I...

5. Coupling metric-affine gravity to a Higgs-like scalar field

Claire Rigouzzo

13/02/2023, 16:50

General relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, we focus on metric-affine gravity, which avoids any assumption about the vanishing of curvature, torsion, or nonmetricity. We use it to construct an action of a scalar field coupled...

4. A generalization of Einstein’s quadrupole formula for radiated energy in de Sitter spacetime

Denis Dobkowski-Ryłko

13/02/2023, 17:10

We consider gravitational radiation produced by a time changing matter source in de Sitter spacetime. A Killing horizon is used as a generalization of the conformal boundary used in the radiation theory in Minkowski spacetime. We derived the expression for the energy of the radiation passing through the horizon. Our result takes the form of a generalized quadrupole formula expressed in terms...

6. Massless Dirac Perturbations in a Consistent Model of Loop Quantum Gravity Black Holes: Quasinormal Modes and Greybody factor

Saulo Soares de Albuquerque Filho

13/02/2023, 18:00

We consider perturbations of the massless Dirac field in the background of a black hole solution found by Bodendorfer, Mele and Münch (BMM), using a polymerization technique that furnishes contributions inspired by loop quantum gravity. Using the 6th order WKB method, we analyzed its quasinormal modes for several modes, multipole numbers and the two classes of BMM black holes. We also...

7. Fundamental decoherence from quantum spacetime

Vittorio D'Esposito

13/02/2023, 18:20

9. Determinism at a black hole singularity

Martina Adamo

14/02/2023, 11:30

10. Quantum correction to black hole entropy

Filip Požar

14/02/2023, 11:50

I will discuss the semiclassical brick wall method of calculating the entropy of black holes. The brick wall is based on the WKB approximation and it can be used to calculate black hole entropy's corrections due to, e.g., the inclusion of noncommutative geometry into Einstein's equations.

11. Entanglement entropy and the emergence of an arrow of time in the early universe

Mritunjay Tyagi

14/02/2023, 12:10

Roger Penrose's Weyl curvature hypothesis can be extended to the quantum regime, where 'past singularities' have to be replaced by 'regions of small enough scale factors' in the configuration space of the wave function of the universe. At a fundamental level the justification for the quantum version of the Weyl Curvature hypothesis is expected to come from a full quantum theory of gravity :...

12. Rainbow Oppenheimer-Snyder collapse and the entanglement entropy production

Michał Bobula

14/02/2023, 12:30

I derive a new model of black-to-white hole transition - the classical Oppenheimer-Snyder dust ball interior is modified with Loop Quantum Cosmology dynamics. I consider the rainbow metric approach for both pure dust ball collapse and the similar scenario accounting for scalar field perturbations. The collapsing matter bounces and reemerges in a new universe. Exterior geometry is extracted as...

13. The time problem and primordial perturbations

Alice Boldrin

14/02/2023, 12:50

The problem of time in physics arises from the conceptual discrepancies between non-relativistic and relativistic time.
The principle of general covariance in general relativity gives us the freedom to choose an arbitrary clock for our theory. In quantum mechanics, however, different choices of internal time variables are known to produce unitarily inequivalent quantum models.
In my...

14. Prescriptions and analytic control over quantum dynamics in loop quantum cosmology

Maciej Kowalczyk

14/02/2023, 13:10

Ambiguities of the so-called Thiemann regularization in Loop Quantum Cosmology lead to freedom in how to construct a particular quantization prescription, which in turn may significantly affect the mathematical structure of the quantum model and its dynamical predictions. Out of several prescriptions presented in the literature I will focus on one showing somewhat counterintuitive properties,...

16. Quasinormal modes in teleparallel gravity

Vasilki Karanasou

15/02/2023, 15:00

Small perturbations of spherical symmetric Schwarzschild backgrounds in General Relativity have been already discussed since 1957 by Regge and Wheeler [1] and the quasinormal frequencies of relativistic stars and black holes that emit gravitational waves have been investigated by Nollert [2], Kokkotas and Schmidt [3] as well since 1999. Considering the quite recent detection of gravitational...

15. Energy and entropy in the Geometrical Trinity of gravity

Débora Aguiar Gomes

15/02/2023, 15:20

All energy is gravitational energy. That is the consequence of the equivalence principle, according to which gravity is the universal interaction. 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-independent unification of the previous,...

8. 5D Chern-Simons Gravity, RS Braneworld and Holography

Dusan Djordjevic

15/02/2023, 15:40

Five-dimensional Chern-Simons gravity is very interesting theory that allows for a space-time to have both nonzero curvature and torsion , yet it is defined in one higher number of dimensions than we currently experimentally observe. In this talk, we will review some aspects of five-dimensional Chern-Simons gravity with AdS gauge group. Using holography as our guiding tool, we will write down...

18. Quantum Euler angles and agency-dependent spacetime

Domenico Frattulillo

15/02/2023, 16:30

19. θ-angle physics of two color QCD: fixed baryon charge and near conformal dynamics

Alessandra D'Alise

15/02/2023, 16:50

20. Solving constraints using quantum computers

Grzegorz Czelusta

15/02/2023, 17:10

One of the central difficulties in the quantization of the gravitational interactions is that they are described by a set of constraints. We propose and investigate a new methods of solving constraints equations, which employ a variational quantum computing approach and projection approach, possible to implement on quantum computers. For the purpose of testing our methods, both an emulator of...

21. Study of Universe Transparency in an LIV Framework

Filip Rescic

18/02/2023, 15:00

22. LIV search with the Crab Pulsar

Anna Campoy Ordaz

18/02/2023, 15:20

23. Atom interferometry and small-scale tests of general relativity

Mikolaj Myszkowski

18/02/2023, 15:40

Since the first appearance of general relativity in 1916, various experiments have been conducted to test the theory. Due to the weakness of the interactions involved, all of the documented tests were carried out in a gravitational field generated by objects of an astronomical scale. We explain what atom interferometers are and how they can be used to test general relativity in the small-scale...

24. Noncommutative gravity using twists

Nikola Herceg

18/02/2023, 16:30

The formalism of Hopf algebras and Drinfeld twist are introduced along with noncommutative star-product. Star-product is then generalised to differential-geometric structures: vector fields, forms, connection,... Perturbations of Schwarzschild spacetime are then investigated as a practical example. A brief overview of the standard BH perturbation theory can also be given (depending on the...

25. k-Braided noncommutative field theory

Maria Grazia Di Luca

18/02/2023, 16:50

26. Total momentum and other Noether charges for particles interacting in a quantum spacetime

Giuseppe Fabiano

18/02/2023, 17:10

27. κ-deformed complex fields, (discrete) symmetries, and charges

Andrea Bevilacqua

18/02/2023, 17:30

In this talk I will briefly describe a construction of a κ-deformed complex scalar field theory, while at the same time shedding light on the behaviour of discrete and continuous symmetries in this formalism. This in turn will open the way to the study of the application of this formalism to actual physical processes. I will then conclude with some comments and prospects for the future.

17. Hamilton's equations in the (covariant) teleparallel equivalent of general relativity

Laxmipriya Pati

We present Hamilton's equations for the teleparallel equivalent of general relativity (TEGR), which is a reformulation of general relativity based on a curvatureless, metric compatible, and torsionful connection. For this, we consider the Hamiltonian for TEGR obtained through the vector, antisymmetric, symmetric and trace-free, and trace irreducible decomposition of the phase space variables....