### Conveners

#### Quantum Gravity Phenomenology: Block 1

- Jerzy Kowalski-Glikman (Institute for Theoretical Physics, University of Wroclaw, Poland; National Centre for Nuclear Research, Warsaw, Poland)
- Giovanni Amelino-Camelia (Università Federico II di Napoli)

#### Quantum Gravity Phenomenology: Block 2

- Giovanni Amelino-Camelia (Università Federico II di Napoli)
- Jerzy Kowalski-Glikman (Institute for Theoretical Physics, University of Wroclaw, Poland; National Centre for Nuclear Research, Warsaw, Poland)

#### Quantum Gravity Phenomenology: Block 3

- Giovanni Amelino-Camelia (Università Federico II di Napoli)
- Jerzy Kowalski-Glikman (Institute for Theoretical Physics, University of Wroclaw, Poland; National Centre for Nuclear Research, Warsaw, Poland)

### Description

This session will be devoted to discussion of phenomenological models aimed at probing and possibly leading to detection of various phenomena of quantum gravity origin. Such models are particularly timely now, at the down of the multi-messenger astronomy, which give us an access to new observations, possibly capable of detecting Planck-scale effects. The aim of the session will be to present recent developments in both theoretical investigations and current and near-future observational opportunities.

In my talk I will introduce kappa-deformation of discrete symmetries and I will discuss its phenomenological consequences.

A minimal length is generally expected to result in Lorentz-violating dispersion relations. I show how one can formulate a lattice theory that carries a representation of the Poincaré group in the Brillouin zone, and discuss how light cones arise for a subalgebra of observables. [Based on work in collaboration with Bekir Baytaş and Pietro Donà]

There has been an expectation that the presence of the *Barbero-Immirzi* parameter ($\gamma$) in Loop Quantum Gravity (LQG) results in a quantum correction to the classical theory of gravity in the form of parity violation in primordial gravitational waves. In this paper, we show that a discreet symmetry of the Spinfoams action, $\gamma$-duality, constrains the form of the effective action for...

We derive the effective polymer Hamiltonian of gravitational waves propagating on an FLRW background. We overcome the problem of polymerizing a time-dependent system by using a novel approach by using the extended phase space approach. Using the resulting Hamiltonian, we study some of the possible observational consequences of such a polymerized gravitational wave Hamiltonian.

Quantum gravity effects are traditionally tied to short distances and high energies. In this talk I will argue that, perhaps surprisingly, quantum gravity may have important consequences for the phenomenology of the infrared. I will center my discussion around a conception of quantum gravity involving a notion of quantum spacetime that arises in metastring theory. This theory allows for an...

We explore the phenomenological viability of scenarios, suggested by different approaches to quantum spacetime, where quantum-gravity effects in the propagation of particles are triggered by spacetime curvature/expansion.

We rely on a toy model of curvature-induced Lorentz violation for a preliminary exploration, and we find that, differently from what commonly believed, the double...

We study Quantum Gravity effects in cosmology, and in particular that of the Generalized Uncertainty Principle on the Friedmann equations. We show that the Quantum Gravity induced variations of the energy density and pressure in the radiation dominated era provide a viable explanation of the observed baryon asymmetry in the Universe.

In my talk I shall discuss how big is the parameter space of the couplings at the Planck scale leading to correct non-susy unification for the SO(10). To do so have calculated the renormalisation group equations for the model and run them down towards the IR and investigated the effective potential. As it turns out the initial parameters has to lie in the very small intervals and have a huge...

Recently the entanglement entropy between universes has been calculated, an entropy which somehow describes the quantumness of a homogeneous multiverse. The third quantization formalism of canonical quantum gravity is used here. I will show improvements of the results in a more general scenario, studying what happens at critical points of the evolution of a classical universe. We infer the...

We argue that the minimal length uncertainty emerging from the generalized uncertainty principle, in which the gravitational impacts on the noncommutative space are thoughtfully taken into account, modifies the whole spacetime geometry. The resulting spacetime metric tensor consists of the symmetric GR compatible metric tensor $g_{\mu \nu}$ and another term comprising $g_{\mu \nu}$ multiplied...

The problem of time arising in Quantum Gravity is a core problem for which a common solution is not yet identified. In this talk we will examine the semiclassical approach to the dynamics of a gravity-matter system, with the goal of reproducing the standard quantum field theory on a fixed Wentzel-Kramer-Brillouin metric background and, at the next order of expansion, computing the quantum...

Some of the most prominent theoretical predictions of modern times, e.g., the Unruh effect, Hawking radiation, and gravity-assisted particle creation, are supported by the fact that various quantum constructs like particle content and vacuum fluctuations of a quantum field are observer-dependent. Despite being fundamental in nature, these predictions have not yet been experimentally verified...

We are using the book “Towards Quantum Gravity with an article by Claus Kiefer as to a quantum gravity interpretation of the density matrix in the early universe. The density matrix we are using is a one loop approximation, with inflaton value and potential terms, like V(phi) using the Padmanabhan values one can expect if the scale factor is a ~ a(Initial) times t ^ gamma , from early times ....

Theories of Quantum Gravity predict a minimum measurable length and a corresponding modification of the Heisenberg Uncertainty Principle to the so-called Generalized Uncertainty Principle (GUP). However, this modification is non-relativistic, making it unclear whether the minimum length is Lorentz invariant. We formulate a Relativistic Generalized Uncertainty Principle, resulting in a Lorentz...

Many quantum gravity theories predict several interesting phenomenological features such as minimal length scales and maximal momenta. Generalized uncertainty principles (GUPs), which are extensions of the standard Heisenberg uncertainty principle, have proven very useful in modelling the effects of such features on physics at sub-Planck energy scales. In this talk, we use a GUP modelling...

We study Quantum Gravity effects on the density of states in statistical mechanics and its implications for the critical temperature of a Bose Einstein Condensate and fraction of bosons in its ground state. We also study the effects of compact extra dimensions on the critical temperature and the fraction. We consider both neutral and charged bosons in the study and show that the effects may...

This abstract is primarily based on my recent paper IJMPD 30, 05 (2021) 2150034, along with arXiv: 2101.06272.

Over the past decades, various researchers have indirectly predicted at least a dozen super-Chandrasekhar white dwarfs (white dwarfs which violate the Chandrasekhar mass-limit) from the luminosity observations of type Ia supernovae. Several research groups worldwide proposed...