arXiv subjects

Paolo Castorina

Publications and source records attributed to Paolo Castorina.

At least 19 recordsLinked to original sources

arXiv2026

On the dilaton gravity of analogue black holes

We investigate which dilaton gravity models can reproduce the typical two dimensional analogue black holes realized in platforms such as superconducting quantum circuits. We identify the most reasonable assumptions these models must satisfy, and determine the dilaton models for which the state-dependence of the Hawking temperature, T, can be switched on and off, a feature that is absent in four dimensional black holes. When the analogue black hole exhibits state-independent temperature, as in the cases considered here, the kinematics governing T decouples from the dynamics underlying S. Our numerical analysis reveals that the given analogue black holes do not correspond to known dilaton gravity models, limiting their usefulness for extracting theoretical insights. We then show that the logic can be easily reversed: starting from established well known dilaton models, one can derive the conditions that laboratory implementations must satisfy. This shifts the challenge from the theoretical perspective to the experimental realization.

hep-th↗

arXiv2024

Aharonov-Bohm effect for confined matter in lattice gauge theories

Gauge theories arise in physical systems displaying space-time local symmetries. They provide a powerful description of important realms of physics ranging from fundamental interactions, to statistical mechanics, condensed matter and more recently quantum computation. As such, a remarkably deep understanding has been achieved in the field. With the advent of quantum technology, lower energy analogs, capable to capture important features of the original quantum field theories through quantum simulation, have been intensively studied. Here, we propose a specific scheme implementing an analogic quantum simulation of lattice gauge theories constrained to mesoscopic spatial scales. To this end, we study the dynamics of mesons residing in a ring-shaped lattice of mesoscopic size pierced by an effective magnetic field. In particular, we find a new type of Aharonov-Bohm effect that goes beyond the particle-like effect and reflecting the the features of the confining gauge potential. The coherence properties of the meson are quantified by the persistent current and by specific features of the correlation functions. When the magnetic field is quenched, Aharonov-Bohm oscillations and correlations start a specific matter-wave current dynamics.

cond-mat.quant-gas↗

arXiv2023

Probe for bound states of SU(3) fermions and colour deconfinement

Fermionic artificial matter realized with cold atoms grants access to an unprecedented degree of control on sophisticated many-body effects with an enhanced flexibility of the operating conditions. We consider three-component fermions with attractive interactions to study the formation of complex bound states whose nature goes beyond the standard fermion pairing occurring in quantum materials. Such systems display clear analogies with quark matter. Here, we address the nature of the bound states of a three-component fermionic system in a ring-shaped trap through the persistent current. In this way, we demonstrate that we can distinguish between color superfluid and trionic bound states. By analyzing finite temperature effects, we show how finite temperature can lead to the deconfinement of bound states. For weak interactions the deconfinement occurs because of scattering states. In this regime, the deconfinement depends on the trade-off between interactions and thermal fluctuations temperature. For strong interactions the features of the persistent current result from the properties of a suitable gas of bound states.

cond-mat.quant-gas↗

arXiv2022

Hunting Quantum Gravity with Analogs: the case of High Energy Particle Physics

In this review we collect, for the first time in one paper, old and new results and future perspectives of the research line that uses hadron production, in high-energy scattering processes, to experimentally probe fundamental questions of quantum gravity. The key observations, that ignited the link between the two arenas, are the so-called ``color-event horizon'' of quantum chromodynamics, and the enormous (de)accelerations involved in such scattering processes: both phenomena point to the Unruh (and related Hawking) type of effects. After the first pioneering investigations of this, such research went on and on, including studies of the horizon entropy and other ``black-hole thermodynamical'' behaviors, which incidentally are also the frontier of the analog gravity research itself. It is stressed in various places here that the \textit{trait d'union} between the two phenomenologies is that in both scenarios, hadron physics and black hole physics, ``thermal'' behaviors are more easily understood not as due to real thermalization processes (sometimes just impossible, given the small number of particles involved), but rather to a stochastic/quantum entanglement nature of such temperature. Finally, other aspects, such as the self-critical organizations of hadronic matter and of black-holes, have been recently investigated. The results of those investigations are also summarized and commented upon here. As a general remark, this research line shows that indeed we can probe quantum gravity theoretical constructions with analog systems that are not confined to belong only to the condensed matter arena. This is as it must be.

hep-ph↗

arXiv2022

Quantum black holes, partition of integers and self-similarity

We take the view that the area of a black hole's event horizon is quantized, $A = l_P^2 \, (4 \ln 2) \, N$, and the associated degrees of freedom are finite in number and of fermionic nature. We then investigate general aspects of the entropy, $S_{BH}$, our main focus being black-hole self-similarity. We first find a two-to-one map between the black hole's configurations and the ordered partitions of the integer $N$. Hence we construct from there a composition law between the sub-parts making the whole configuration space. This gives meaning to black hole self-similarity, entirely within a single description, as a phenomenon stemming from the well known self-similarity of the ordered partitions of $N$. Finally, we compare the above to the well-known results on the subleading (quantum) corrections, that necessarily require different (quantum) statistical weights for the various configurations.

physics.gen-ph↗

arXiv2020

Fluctuations and thermodynamic geometry of the chiral phase transition

We study the thermodynamic curvature, $R$, around the chiral phase transition at finite temperature and chemical potential, within the quark-meson model augmented with meson fluctuations. We study the effect of the fluctuations, pions and $σ$-meson, on the top of the mean field thermodynamics and how these affect $R$ around the crossover. We find that for small chemical potential the fluctuations enhance the magnitude of $R$, while they do not affect substantially the thermodynamic geometry in the proximity of the critical endpoint. Moreover, in agreement with previous studies we find that $R$ changes sign in the pseudocritical region, suggesting a change of the nature of interactions at the mesoscopic level from statistically repulsive to attractive. Finally, we find that in the critical region around the critical endpoint $|R|$ scales with the correlation volume, $|R| =K\;ξ^3$, with $K = O(1)$, as expected from hyperscaling; far from the critical endpoint the correspondence between $|R|$ and the correlation volume is not as good as the one we have found at large $μ$, which is not surprising because at small $μ$ the chiral crossover is quite smooth; nevertheless, we have found that $R$ develops a characteristic peak structure, suggesting that it is still capable to capture the pseudocritical behavior of the condensate.

hep-ph↗

arXiv2020

Stability of Schwarzschild (Anti)de Sitter black holes in Conformal Gravity

We study the thermodynamics of spherically symmetric, neutral and non-rotating black holes in conformal (Weyl) gravity. To this end, we apply different methods: (i) the evaluation of the specific heat; (ii) the study of the entropy concavity; (iii) the geometrical approach to thermodynamics known as \textit{thermodynamic geometry}; (iv) the Poincaré method that relates equilibrium and out-of-equilibrium thermodynamics. We show that the thermodynamic geometry approach can be applied to conformal gravity too, because all the key thermodynamic variables are insensitive to Weyl scaling. The first two methods, (i) and (ii), indicate that the entropy of a de Sitter black hole is always in the interval $2/3\leq S\leq 1$, whereas thermodynamic geometry suggests that, at $S=1$, there is a second order phase transition to an Anti de Sitter black hole. On the other hand, we obtain from the Poincaré method (iv) that black holes whose entropy is $S < 4/3$ are stable or in a saddle-point, whereas when $S>4/3$ they are always unstable, hence there is no definite answer on whether such transition occurs.

hep-th↗

arXiv2020

Gluon Shadowing and Nuclear Entanglement

Relying on previous results that link entanglement entropy and parton distribution functions in deep inelastic scattering and focusing on the small Bjorken scaling region we present here indications that gluon shadowing might indeed be explained as due to a depletion of the entanglement entropy between observed and unobserved degrees of freedom per nucleon within a nucleus with respect to the free nucleon case. We apply to gluon shadowing the general Page approach to the calculation of the entanglement entropy in bipartite systems, giving physical motivations of the results.

hep-ph↗

arXiv2019

Universality in Hadronic and Nuclear Collisions at High Energy

Recent experimental results in proton-proton and in proton-nucleus collisions at Large Hadron Collider energies show a strong similarity to those observed in nucleus-nucleus collisions, where the formation of a quark-gluon plasma is expected. We discuss the comparison between small colliding systems and nucleus-nucleus collisions, for: a)~the strangeness suppression factor $γ_s$ and yields of multi-strange hadrons; b)~the average transverse momentum, $p_t$, with particular attention to the low $p_t$ region where soft, non-perturbative effects are important; c)~the elliptic flow scaled by the participant eccentricity. The universal behavior in hadronic and nuclear high energy collisions emerges for all these observables in terms of a specific dynamical variable which corresponds to the entropy density of initial system in the collision and which takes into account the transverse size of the initial configuration and its fluctuations.

hep-ph↗

arXiv2019

High Energy Hadron Production as Self-Organized Criticality

In high energy nuclear collisions, production rates of light nuclei as well as those of hadrons and hadronic resonances agree with the predictions of an ideal gas at a temperature T = 155 +/- 10 MeV. In an equilibrium medium of this temperature, light nuclei cannot survive. We propose that the observed behavior is due to an evolution in global non-equilibrium, leading to self-organized criticality. At the confinement point, the initial quark-gluon medium becomes quenched by the vacuum, breaking up into all allowed free hadronic and nuclear mass states, without formation of any subsequent thermal hadronic medium.

hep-ph↗

arXiv2018

Thermodynamic Geometry and Deconfinement Temperature

The application of Riemannian geometry to the analysis of the equilibrium thermodynamics in Quantum Chromodynamics (QCD) at finite temperature and baryon density gives a new method to evaluate the critical temperature, $T_c$, of the deconfinement transition. In the confined phase, described by the thermodynamic geometry of the Hadron Resonance Gas, the estimate of $T_c$ turns out completely consistent with lattice QCD simulations of the quark-gluon plasma phase if the hadron excluded volume and the interaction effects are taken into account.

nucl-th↗

arXiv2018

Phase Space Non-commutativity and its Stability

We consider a generalised non-commutative space-time in which non-commutativity is extended to all phase space variables. If strong enough, non-commutativity can affect stability of the system. We perform stability analysis on a couple of simple examples and show that a system can be stabilised by introducing quartic interactions provided they satisfy phase-space copositivity. In order to conduct perturbative analysis of these systems one can use either canonical methods or phase-space path integral methods which we present in some detail.

hep-th↗

arXiv2018

Confinement Horizon and QCD Entropy

Within the picture of quark confinement as due to a \textit{color event horizon}, and of hadronization as an instance of the Unruh radiation for the strong force, we show here that QCD entropy, evaluated by lattice simulations in the region $T_c < T < 1.3 T_c$, is in reasonable agreement with a melting color event horizon.

hep-ph↗

arXiv2017

Test of Space-Time Non-Commutativity at the Future Circular Collider

The Future Circular Collider (FCC) is a crucial step forward to study new Physics beyond the standard model and to test fundamental aspects as space-time minimal length and Lorentz violations. As an example, a possible enhancement of $e^+e^-$ pair production due to non-commutative effects, catalyzed by the huge magnetic field produced at the beginning of a heavy ion collision at FCC, is discussed. In noncommutative electrodynamics a free photon in the magnetic background can produce a $e^+e^-$ pair. In particular for hard photons with transverse energy $100-600$ GeV at the beginning of the collision and for a particular kinematical setting of the pair , i.e. large total transverse momentum in the reaction plane and invariant mass in the range $200-400$ MeV, the non-commutative contribution, evaluated with the present bound of the non-commuativity fundamental area , can be significant. Other, more exotic, possible signatures of space-time non-commutativity are also considered.

hep-ph↗

arXiv2017

Strangeness Production and Color Deconfinement

The relative multiplicities for hadron production in different high energy collisions are in general well described by an ideal gas of all hadronic resonances, except that under certain conditions, strange particle rates are systematically reduced. We show that the suppression factor gamma_s, accounting for reduced strange particle rates in pp, pA and AA collisions at different collision energies, becomes a universal function when expressed in terms of the initial entropy density s_0 or the initial temperature T of the produced thermal medium. It is found that gamma_s increases from about 0.5 to 1.0 in a narrow temperature range around the quark-hadron transition temperature T_c = 160 MeV. Strangeness suppression thus disappears with the onset of color deconfinement; subsequently, full equilibrium resonance gas behavior is attained.

nucl-th↗

arXiv2017

Effects of ultra-light dark matter on the gravitational quantum well

We study the influence of a periodic perturbation of the effective masses of the nucleons, due to the assumed semi-classical ultra-light dark matter background, on the motion of neutrons in a gravitational quantum well. Our focus is on the transition probability between the lowest two energy states, with the Rabi frequency in the kHz region corresponding to the series of "sweet spot" dark matter masses in the $10^{-11}$eV ballpark. The relevant probability is written in terms of the specific mass and of the effective coupling to the ordinary matter. These parameters can be constrained by the non-observation of any significant deviations of the measured transition probabilities from the dark-matter-free picture.

hep-ph↗

arXiv2015

QCD Equation of State and Cosmological Parameters in Early Universe

The time evolution of cosmological parameters in early Universe at the deconfinement transition is studied by an equation of state (EoS) which takes into account the finite baryon density and the background magnetic field. The non perturbative dynamics is described by the Field Correlator Method (FCM) which gives, with a small number of free parameters, a good fit of lattice data. The entire system has two components, i.e. the quark-gluon plasma and the electroweak sector, and the solutions of the Friedmann equation show that the scale factor, $a(t)$, and $H(t)= (1/a)da/dt$ are weakly dependent on the EoS, but the deceleration parameter, $q(t)$, and the jerk, $j(t)$, are strongly modified above the critical temperature $T_c$, corresponding to a critical time $t_c \simeq 20-25 μs$. The time evolution of the cosmological parameters suggest that above and around $T_c$ there is a transient state of acceleration typical of a matter dominated Universe; this is entailed by the QCD strong interaction driven by the presence of massive colored objects.

hep-ph↗

arXiv2014

Hadron Freeze-Out and Unruh Radiation

We consider hadron production in high energy collisions as an Unruh radiation phenomenon. This mechanism describes the production pattern of newly formed hadrons and is directly applicable at vanishing baryochemical potential, mu = 0. It had already been found to correctly yield the hadronisation temperature, T_h = sqrt(sigma / 2 pi) = 165 MeV in terms of the string tension sigma. Here we show that the Unruh mechanism also predicts hadronic freeze-out conditions, giving s/T_h^3 = 3 pi^2 / 4 = 7.4 in terms of the entropy density s and E/N = \sqrt(2 pi sigma) = 1.09 for the average energy per hadron. These predictions provide a theoretical basis for previous phenomenological results and are also in accord with recent lattice studies.

hep-ph↗