arXiv subjects

Andrea Addazi

Publications and source records attributed to Andrea Addazi.

At least 73 records · Page 4Linked to original sources

arXiv2020

Generalized Holographic Principle, Gauge Invariance and the Emergence of Gravity a la Wilczek

We show that a generalized version of the holographic principle can be derived from the Hamiltonian description of information flow within a quantum system that maintains a separable state. We then show that this generalized holographic principle entails a general principle of gauge invariance. When this is realized in an ambient Lorentzian space-time, gauge invariance under the Poincare group is immediately achieved. We apply this pathway to retrieve the action of gravity. The latter is cast a la Wilczek through a similar formulation derived by MacDowell and Mansouri, which involves the representation theory of the Lie groups SO(3,2) and SO(4,1).

gr-qc↗

arXiv2020

Multi-boundary entanglement in Chern-Simons theory with finite gauge groups

We study the multi-boundary entanglement structure of the states prepared in (1+1) and (2+1) dimensional Chern-Simons theory with finite discrete gauge group $G$. The states in (1+1)-$d$ are associated with Riemann surfaces of genus $g$ with multiple $S^1$ boundaries and we use replica trick to compute the entanglement entropy for such states. In (2+1)-$d$, we focus on the states associated with torus link complements which live in the tensor product of Hilbert spaces associated with multiple $T^2$. We present a quantitative analysis of the entanglement structure for both abelian and non-abelian groups. For all the states considered in this work, we find that the entanglement entropy for direct product of groups is the sum of entropy for individual groups, i.e. $\text{EE}(G_1 \times G_2) = \text{EE}(G_1)+\text{EE}(G_2)$. Moreover, the reduced density matrix obtained by tracing out a subset of the total Hilbert space has a positive semidefinite partial transpose on any bi-partition of the remaining Hilbert space.

hep-th↗

arXiv2019

Analogous BMS Symmetry in QED and Quantum Anomaly in Dirac and Weyl Semimetals

We show that the asymptotic infinite dimensional enlarged gauge symmetries constructed for QED are anomalous in Dirac and Weyl semimetals. This symmetry is particularly important in particle physics for its analogy with the Bondi-Metzner-Sachs (BMS) symmetries in gravity, as well as for its connection with QED soft IR theorems. This leads to observable effects, because of the induction of a new current in the material, which carries a memory of the BMS symmetry precursor.

cond-mat.mes-hall↗

arXiv2019

Gravitational Instability of Exotic Compact Objects

Exotic compact objects with physical surfaces a Planckian distance away from where the horizon would have been are inspired in quantum gravity. Most of these objects are defined by a classical spacetime metric, such as boson stars, gravastars and wormholes. We show that these classical objects are gravitationally unstable because accretion of ordinary and dark matter, and gravitational waves forces them to collapse to a black hole by the Hoop conjecture. To avoid collapse, their surface must be a macroscopic distance away from the horizon or they must violate the null energy condition.

gr-qc↗

arXiv2019

Conformal Bootstrap in dS/CFT and Topological Quantum Gravity

We show that the correspondence among $AdS_{3}/CFT_{2}$, the 1D Schwarzian Model, Sachdev-Ye-Kitaev model and 2+1D Topological Quantum Gravity can be extended to the case of $dS_{3}/CFT_{2}$. The $R$-matrix, related to the gravitational scattering amplitude near the horizon of $dS_{3}$ black hole, corresponds (on the side of the holographic projection) to a crossing kernel in the Schwarzian Model. The $R$-matrix is related to the 6j-symbol of SU$(1,1)$. We also find that in the Euclidean $dS_{3}$ a new Kac-Moody symmetry of instantons emerges out. We dub these new solutions {\it Kac-Moodions}. A one-to-one correspondence of Kac-Moodion levels and SU$(2)$ spin representations is established. Every instanton then corresponds to spin representations deployed in Topological Quantum Gravity. The instantons are directly connected to the Black Hole entropy, as punctures on its horizon. This strongly supports the recent proposal, in arXiv:1707.00347, that a Kac-Moody symmetry of gravitational instantons is related to the black hole information processing. We also comment on a further correspondence that can be established between the Schwarzian Model and non-commutative spacetimes in 2+1D, passing through the equivalence with Topological Quantum Gravity with cosmological constant, in the limit when the latter vanishes.

hep-th↗

arXiv2019

Probing Trans-electroweak First Order Phase Transitions from Gravitational Waves

We propose direct tests of very high energy first-order phase transitions, which are elusive to collider physics, deploying the gravitational waves measurements. We show that first-order phase transitions lying into a large window of critical temperatures, which is considerably larger than the electroweak energy scale, can be tested from aLIGO and Einstein Telescope. This provides the possibility to probe several inflationary mechanisms ending with the inflaton in a false minimum, and high-energy first order phase transitions that are due to new scalar bosons, beyond the Standard Model of particle physics. As an important example, we consider the axion monodromy inflationary scenario, and analyze the potential for its experimental verification, deploying the gravitational wave interferometers.

hep-ph↗

arXiv2019

Solar System and Atomic Stronger Bounds on Exotic Dyonic Matter and Non-associative Quantum Mechanics

We derive stronger bounds on the magnetic monopole charge of the proton, and hence on non-associative quantum mechanics from measurements of the magnetic fields of the Earth, the Moon and Mars. Limits are several orders of magnitude stronger than the ones inferred from the Hydrogen atomic levels, assuming that electrons do not retain a magnetic monopole charge. Conversely, we show how to estimate bounds on the magnetic charge of a proton correctly, when the magnetic monopole charge of the electron is taken into account.

physics.gen-ph↗

arXiv2019

Mirror Symmetry of quantum Yang-Mills vacua and cosmological implications

We find an argument related to the existence of a Z_2-symmetry for the renormalization group flow derived from the bare Yang-Mills Lagrangian, and show that the cancellation of the vacuum energy may arise motivated both from the renormalization group flow solutions and the effective Yang-Mills action. In the framework of the effective Savvidy's action, two Mirror minima are allowed, with exactly equal and hold opposite sign energy densities. At the cosmological level, we explore the stability of the electric and magnetic attractor solutions, both within and beyond the perturbation theory, and find that thanks to these latter the cancellation between the electric and the magnetic vacua components is achieved at macroscopic space and time separations. This implies the disappearance of the conformal anomaly in the classical limit of an effective Yang-Mills theory. In this picture, the tunneling probability from the Mirror vacua to the other vacua is exponentially suppressed in the quantum non-thermal state --- similarly to what happens for electroweak instantonic tunneling solutions. Specifically, we show that, in a dynamical Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological background, the Nielsen-Olsen argument --- on the instability of uniform chromo-electric and chromo-magnetic Mirror vacua --- is subtly violated. The chromo-magnetic and chromo-electric uniform vacua are unstable only at asymptotic times, when the attractor to a zero energy density is already reached. The two vacua can safely decay into one anisotropic vacuum that has zero energy-density. We also discover a new surprising pattern of solitonic and anti-solitonic space-like solutions, which are sourced by the Yang-Mills dynamics in FLRW. We dub such non-perturbative configurations, which are directly related to dynamical cancellation mechanism of the vacuum energy, as {\it chronons}, or $χ$-solutions.

hep-th↗

arXiv2019

Emergent inflation from a Nambu--Jona-Lasinio mechanism in gravity with non-dynamical torsion

We discuss how inflation can emerge from a four-fermion interaction induced by torsion. Inflation can arise from coupling torsion to Standard Model fermions, without any need of introducing new scalar particles beyond the Standard Model. Within this picture, the inflaton field can be a composite field of the SM-particles and arises from a Nambu-Jona-Lasinio mechanism in curved space-time, non-minimally coupled with the Ricci scalar. The model we specify predicts small value of the r-parameter, namely $r\sim 10^{-4} ÷10^{-2}$, which nonetheless would be detectable by the next generation of experiments, including BICEP 3 and the AliCPT projects.

gr-qc↗

arXiv2019

Soft gravitational radiation from ultra-relativistic collisions at sub- and sub-sub-leading order

Using soft-graviton theorems a well-known zero-frequency limit (ZFL) for the gravitational radiation flux $dE^{GW}/d ω$ is re-derived and extended to order ${\cal O}(ω)$ and ${\cal O}(ω^2)$ for arbitrary massless multi-particle collisions. The (angle-integrated, unpolarized) ${\cal O}(ω)$ correction to the flux turns out to be absent in the case of two-particle elastic collisions. The ${\cal O}(ω^2)$ correction is instead non-vanishing and takes a simple general expression which is then applied to bremsstrahlung from two-particle elastic collisions. For a tree-level process the outcome is finite and consistent with expectations. Instead, if the tree-level form of the soft theorems is used at sub-sub-leading order even when the elastic amplitude needs an all-loop (eikonal) resummation, an unphysical infrared singularity occurs. Its origin can be traced to the infinite Coulomb phase of gravitational scattering in four dimensions. We briefly discuss how to get rid, in principle, of the unwanted divergences and indicate --without carrying out-- a possible procedure to find the proper correction to the naive soft theorems. Nevertheless, if a simple recipe recently proposed for handling these divergences is adopted, we find surprisingly good agreement with results obtained independently via the eikonal approach to transplanckian-energy scattering at large (small) impact parameter (deflection angle), where such Coulomb divergences explicitly cancel out.

hep-th↗

arXiv2019

Testing Noncommutative Spacetimes and Violations of the Pauli Exclusion Principle with underground experiments

We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle in order: i) to provide theories of quantum gravity with an experimental guidance; ii) to distinguish among the plethora of possible models the ones that are already ruled out by current data; iii) to direct future attempts to be in accordance with experimental constraints. We firstly review experimental bounds on nuclear processes forbidden by the Pauli Exclusion Principle, which have been derived by several experimental collaborations making use of different detector materials. Distinct features of the experimental devices entail sensitivities on the constraints hitherto achieved that may differ one another by several orders of magnitude. We show that with choices of these limits, renown examples of flat noncommutative space-time instantiations of quantum gravity can be heavily constrained, and eventually ruled out. We devote particular attention to the analysis of the $κ$-Minkowski and $θ$-Minkowski noncommutative spacetimes. These are deeply connected to some scenarios in string theory, loop quantum gravity and noncommutative geometry. We emphasize that the severe constraints on these quantum spacetimes, although cannot rule out theories of top-down quantum gravity to whom are connected in various way, provide a powerful limitations of those models that it will make sense to focus on in the future.

hep-th↗

arXiv2018

Tests of Pauli Exclusion Principle Violations from Non-commutative quantum gravity

We review the main recent progresses in non-commutative space-time phenomenology in underground experiments. A popular model of non-commutative space-time is $θ$-Poincaré model, based on the Groenewold-Moyal plane algebra. This model predicts a violation of the Spin-statistic theorem, in turn implying an energy and angular dependent violation of the Pauli Exclusion principle. Pauli Exclusion Principle Violating transitions in nuclear and atomic systems can be tested with very high accuracy in underground laboratory experiments such as DAMA/LIBRA and VIP(2). In this paper we derive that the $θ$-Poincaré model can be already ruled-out until the Planck scale, from nuclear transitions tests by DAMA/LIBRA experiment.

hep-ph↗

arXiv2018

New Standard Model constraints on the scales and dimension of spacetime

Using known estimates for the kaon--antikaon transitions, the mean lifetime of the muon and the mean lifetime of the tau, we place new and stronger constraints on the scales of the multi-fractional theories with weighted and $q$-derivatives. These scenarios reproduce a quantum-gravity regime where fields live on a continuous spacetime with a scale-dependent Hausdorff dimension. In the case with weighted derivatives, constraints from the muon lifetime are various orders of magnitude stronger than those from the tau lifetime and the kaon--antikaon transitions. The characteristic energy scale of the theory cannot be greater than $E_*>3\times 10^2\,{\rm TeV}$, and is tightened to $E_*>9\times 10^{8}\,{\rm TeV}$ for the typical value $α=1/2$ of the fractional exponents in the spacetime measure. We also find an upper bound $d_{\rm H}<2.9$ on the spacetime Hausdorff dimension in the ultraviolet. In the case with $q$-derivatives, the strongest bound comes from the tau lifetime, but it is about 10 orders of magnitude weaker than for the theory with weighted derivatives.

hep-ph↗

arXiv2018

Time-crystal ground state and production of gravitational waves from QCD phase transition

We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generates a primordial multi-peaked gravitational waves' signal in the radio frequencies' domain. The signal as an echo of the QCD phase transition, and is accessible by the FAST and SKA telescopes.

hep-th↗

arXiv2018

Can we probe Planckian corrections at the horizon scale with gravitational waves?

Future detectors could be used as a gravitational microscope to probe the horizon structure of merging black holes with gravitational waves. But can this microscope probe the quantum regime? We study this interesting question and find that (i) the error in the distance resolution is exponentially sensitive to errors in the Love number, and (ii) the uncertainty principle of quantum gravity forces a fundamental resolution limit. Thus, although the gravitational microscope can distinguish between black holes and other exotic objects, it is resolution limited well above the Planckian scale.

gr-qc↗

arXiv2018

Quantum Ekpyrotic mechanism in Fermi-bounce curvaton cosmology

Within the context of the Fermi-bounce curvaton mechanism, we analyze the one-loop radiative corrections to the four fermion interaction, generated by the non-dynamical torsion field in the Einstein-Cartan-Holst-Sciama-Kibble theory. We show that contributions that arise from the one-loop radiative corrections modify the energy-momentum tensor, {\it mimicking} an effective Ekpyrotic fluid contribution. For these reasons, we call this effect {\it quantum Ekpyrotic} mechanism. This leads to the dynamical washing out of anisotropic contributions to the energy-momentum tensor, without introducing any new extra Ekpyrotic fluid. We discuss the stability of the bouncing mechanism and derive the renormalization group flow of the dimensional coupling constant $ξ$, checking that any change of its sign takes place towards the bounce. This enforces the theoretical motivations in favor of the torsion curvaton bounce cosmology as an alternative candidate to the inflation paradigm.

gr-qc↗

arXiv2018

UV self-completion of a theory of Superfluid Dark Matter

We show that the model of superfluid dark matter developed in Refs.~\cite{Khoury:2014tka,Berezhiani:2015bqa,Berezhiani:2015pia}, which modifies the Newtonian potential and explains the galactic rotational curves, can be unitarized by the formation of classical configurations in the scattering amplitudes. The classicalization mechanism may also trigger the formation of the superfluid state from the early to the late Universe.

hep-th↗

arXiv2018

Testing merging of Dark Exotic Stars from Gravitational Waves in the Multi-messenger approach

We discuss possible implications of the recent detection by the LIGO and VIRGO collaboration of the gravitational-wave event GW170817, the signal of which is consistent with predictions in general relativity on the merging of neutron stars. A near-simultaneous and spatially correlated observation of a gamma-ray burst, the GRB 170817A signal, was achieved independently by the Fermi Gamma-ray Burst Monitor, and by the Anti-coincidence Shield for the Spectrometer of the International Gamma-Ray Astrophysics Laboratory. Motivated by this near temporal and spatial concomitance of events, which can occur by chance only with the probability $5.0 \, \times \, 10^{-8}$, we speculate on the possibility that new dark stars signals could be detected from the LIGO/VIRGO detectors. This proposal, which aims at providing a test for some models of dark matter, relies on the recent achievement of detecting, for visible ordinary matter, the merging of neutron stars both in the gravitational and the electromagnetic channel. A lack of correlation between the two expected signals would suggest a deviation from the properties of ordinary matter. Specifically, we focus on models of invisible dark matter, and in particular we study the case of mirror dark matter, within the framework of which a large amount of mirror neutron stars are naturally envisaged to occupy our dark matter halo. The observation of an electromagnetically hidden event inside the dark matter halo of our galaxy should provide a hint of new physics. There would be indeed no satisfactorily complete explanation accounting for the lack of electromagnetic signal, if only standard neutron star merging were considered to describe events that happen so close to us.

hep-ph↗