We study the back-reaction of a quantum scalar field on anti-de Sitter (AdS) space-time. The renormalized expectation value of the stress-energy tensor operator (RSET) for a quantum scalar field on global AdS space-time acts as a source term on the right-hand-side of the Einstein equations for the quantum-corrected metric. We find the RSETs for rotating and nonrotating thermal states on global...
Zel'dovich and Polnarev, in their seminal paper on the displacement memory effect [1], suggested that particles hit by a burst of gravitational waves generated by flyby would be merely displaced. Their prediction is confirmed by fine-tuning the wave profile, which is the derivative of a Gaussian proposed by Gibbons and Hawking [2], or of its approximation by a P\"oschl-Teller potential. The...
Recently, a renewed interest has emerged towards the possibility that the mass of black holes grow with the expansion of the Universe. This issue was theoretically investigated almost century ago by McVittie but, since then, not much progress was done. However, the recent analysis of a class of elliptical galaxies have open again the possibility that the mass of supermassive black holes can...
Supported by observational evidence indicating that cosmological scalar perturbations were nearly Gaussian at the beginning of the universe, it is anticipated that the origin of these perturbations is quantum fluctuations. Consequently, cosmic inflation provides a valuable setting for testing the quantum nature with/of gravity. Quantumness is characterized by features such as quantum...
In this work, we present a new result concerning the stress-energy
tensor of a quantum field theory at global thermodynamic equilibrium
in curved space-time. By using known exact results in literature
for the massless scalar free field in Minkowski, deSitter, antideSitter and
Einstein static Universe, we demonstrate that the stress-energy
tensor at equilibrium in curved space-time has...
We calculate the energy density and pressure of a scalar field after its decoup-
ling from a thermal bath in the spatially flat Friedman–Lemaître–Robertson–
Walker space-time, within the framework of quantum statistical mechanics.
By using the density operator determined by the condition of local thermo-
dynamic equilibrium, we calculate the mean value of the stress-energy tensor
of a...
The singularity theorems of Penrose and Hawking are based on geodesic incompleteness and predict the occurrence of classical singularities under rather general circumstances. In general relativity, these singularities represent absolute boundaries where space-time ends.
Physically, however, this criterion refers to the fate of point like classical test particles. We raise the question: What...
We develop a non-conventional description of the vacuum energy in quantum field theory in terms of quantum entropy. Precisely, we show that the vacuum energy of any non-interacting quantum field at zero temperature is proportional to the quantum entropy of the qubit degrees of freedom associated with virtual fluctuations. We prove this for fermions first and then extend the derivation to...
In this talk, I will explore the impact of quantum corrections on black holes regarding spacetime inequalities and the weak cosmic censorship conjecture. I will present refined versions of the quantum Penrose and reverse isoperimetric inequalities, valid in three-dimensional asymptotically anti-de Sitter spacetimes, and discuss their implications for cosmic censorship and black hole entropy....
It is common folklore that semiclassical arguments suggest that in black hole evaporation an initially pure state can become mixed. This is known as the \emph{information loss puzzle} (or {\it paradox}). Here we argue that, if taken at face value, semiclassical gravity suggests the formation of a final singularity instead of information loss. A quantum strong cosmic censorship conjecture, for...
General relativity and quantum mechanics are the two frameworks through which we understand Nature. To date, they have been successful at providing accurate predictions of natural phenomena in their respective domains of validity. Many attempts to find a unified theory of Nature that can describe all of observable phenomena have been tried with varying degrees of success. Regardless, the quest...
The de Sitter conjecture yields a severe bound on scalar potentials for a consistent quantum gravity. We extend the de Sitter conjecture by taking into account the kinetic term of the scalar field. We then apply such an extended de Sitter conjecture to a quintessence model of inflation for which dynamics of the scalar field is essential, and obtain an allowed region for parameters of the...
The talk is based on two recent works: 2409.18652 about magnetovortical matter in collaboration with Koichi Hattori and Kazuya Mameda and a forthcoming paper about Chiral EFT for the system where finite $\theta$ and magnetic field $B$ coexist, which was done in collaboration with Prabal Adhikari. In the former, we found a nontrivial interplay between the spin, the orbital angular momentum,...
Unbounded rigidly rotating systems necessarily lead to superluminal motion and are, therefore, considered pathological. Remarkably, recent studies on chiral symmetry breaking under rotation provide similar results in the rigorous bounded and formal unbounded approaches. As a particular example, we consider the linear sigma model coupled with dynamical quarks undergoing rigid rotation in...
In this talk, we will report our recent achievements based on refs. [1,2]. Below are highlights from our results.
Perturbative Confinement under Imaginary Rotation
We perturbatively calculated the Polyakov loop potential at high $T$ by introducing imaginary angular velocity. Under the rapid imaginary rotation, the potential favors zero Polyakov loop, i.e. confinement. In ref. [1],...
In this talk, I first summarize how systems at local thermal equilibrium are described by the partition function of the underlying QFT in a fictitious curved space-time constructed with the hydrodynamic fields [1]. I list how this duality has been used to study systems at thermal equilibrium in the presence of acceleration and rotation. In particular, I show how this helps to describe systems...
We show that, for each symmetry class based on the tenfold way classification of topological insulators/superconductors, the effective Dirac operator obtained by integrating out the additional bulk direction takes a value in the corresponding classifying space, from which we obtain the flat band Hamiltonian. We then obtain the overlap Dirac operator for each symmetry class and establish the...
We study the effect of rotation on the confining and chiral properties of QCD using the linear sigma model with quarks coupled to the Polyakov loop in an attempt to resolve discrepancies between the first principle numerical and model-based analytical results. The rotational effects are incorporated through the formulation of this quasiparticle model in an effectively curved space-time metric....
In this talk, I will explore the impact of field redefinition on the spectrum of linearized perturbations in relativistic hydrodynamics. I show that the spectrum of hydrodynamics modes is never affected by the local field redefinition, however, the spectrum of the non-hydrodynamic modes is affected. Through an appropriate all-order redefinition, non-hydrodynamic modes can be eliminated,...
Effects of ultraviolet completions of gravity can be captured
in low-energy regimes by local higher curvature corrections. Such
description, however, is limited to yield strictly perturbative
corrections, due to unphysical Ostrogradsky instabilities induced by
higher derivatives in the correction terms. I will present a procedure
for expunging spurious degrees of freedom from effective...
Analogue Hawking radiation from acoustic horizons is now a well-established phenomenon, both theoretically and experimentally. Its persistence, despite the modified dispersion relations characterizing phonons in analogue spacetimes, represents an evidence of the robustness of this effect against the ultraviolet non-relativistic modification of the particles' behavior. Previous theoretical...
This talk discusses a new avenue to particle production in curved spacetimes and black hole evaporation using a heat-kernel approach in the context of effective field theory analogous to deriving the Schwinger effect. Applying this method to an uncharged massless scalar field in a Schwarzschild spacetime, we show that spacetime curvature takes a similar role as the electric field strength in...
Recently there has been a considerable debate about possible novel mechanisms for pair creation in the context of quantum field theories in external backgrounds. These results are based on appropriate resummation techniques that allow a nonperturbative analysis of the corresponding theory.
In this talk, we will review new developments in resummations for scalar, gauge and gravitational...
We consider a model of Einstein-Cartan gravity with rectangular vielbein field introduced. A particular case with five internal indexes for the four-dimensional Riemann manifold is explored. As a result we obtain an additional vierbein field absent in the regular formulation of the Einstein-Cartan gravity with equal number of the Riemann and internal indexes. The new vierbein field allows to...
I will discuss the strong-interaction dynamics of tensorial chiral gauge theories in four dimensions, extending previous work on other chiral gauge theories such as the Bars-Yankielowicz or Georgi-Glashow models, based on the consideration of the generalized symmetries and mixed anomalies. The stricter ’t Hooft anomaly matching conditions for these new anomalies strongly suggests the systems...
Anomalous parity violation in four dimensions would be significant for phenomenology (baryogenesis, gravitational waves) and mathematical physics. Over the past decade, there has been a controversy in the literature as to whether free Weyl fermions give rise to (anomalous) parity violation in the trace of the energy momentum tensor; expressed by the Pontryagin densities $R\tilde R$ and...
In recent years, a considerable amount of literature has suggested that spontaneously
broken quantum field theories can undergo a phase transition to an
unbroken phase due to the effect of Unruh radiation, experienced by uniformly
accelerated observers, at sufficiently high accelerations. However, earlier works
(including one by Unruh himself) and standard renormalization techniques...
In this talk, we present a theoretical model to describe a finite-size particle detector, focusing on the derivation of its energy-momentum tensor from a covariant Lagrangian formulation. The model encompasses both the quantum field associated with the detector ($\phi_{\textrm{D}}$) and the elements responsible for its localization: a complex scalar field ($\psi_{\textrm{C}}$) and a perfect...
In the last years, it has been demonstrated that asymptotic symmetries of gravity (the so called BMS group) constrain the gravitational S-matrix. In particular, infrared divergences of the gravitational S-matrix are now understood to arise from to the impossibility of the usual fock space of massless particles to ensure the conservation of the BMS charges.
I will review these results...
Wavefunctions for unitary irreducible representations (UIRs) of the Bondi-Metzner-Sachs (BMS) group are constructed. They are shown to describe quantum superpositions of (Poincaré) particles propagating on inequivalent gravity vacua. This follows from reconsidering McCarthy's classification of BMS group UIRs through a unique, Lorentz-invariant but non-linear, decomposition of supermomenta into...
The purpose of this project is to formulate a kinetic theory describing thermal transport of electrons in a uniform magnetic field of arbitrary magnitude and a temperature gradient. Following Luttinger's point of view, the effect of a temperature gradient is equivalent to a gravitational field and, thus, described by a curvature of spacetime. Using Keldysh formalism, we derive the quantum...
In this talk, we will make a review of the recent achievements of Analogue Gravity in interfacial hydrodynamics with the purpose of probing field theory with tabletop experiments in the laboratory. We will present our daily measurements of Hawking radiation with water waves on the top of a decelerating inhomogeneous current emulating the scattering of light waves by an analogue horizon. We...
A novel oscillatory behaviour of the DC conductivity in Weyl semimetals with vacancies has recently been identified [1], occurring in the absence of external magnetic fields. Here, we argue that this effect has a geometric interpretation in terms of a magnetic-like field induced by an emergent Weyl connection. This geometric gauge field is related to the non-metricity of the underlying...
Quantum field theory in curved spacetimes (QFTCS) predicts the amplification of field excitations and the occurrence of classical and quantum correlations, as in the Hawking effect for example. This raises the interest for experiments in which the curvature of spacetime can be controlled and correlations measured. Such analogue simulations are typically done with fluids accelerating from sub-...
Arnol'd cat maps describe accelerating observers that probe the near horizon geometry of extremal black holes, when the microstates can be resolved. As single particle probes, they display the requisite properties of fast scrambling, that is the hallmark of consistent information processing in black hole spacetimes and they satisfy the non-trivial requirements of eigenstate thermalization....
Ideal hydrodynamics, as a generally covariant theory, can
be considered as a simplified version of general relativity. We will
show that this general covariance is intimately related to statistical
mechanics underlying local thermalization. We will then describe the
problem of including statistical fluctuations in relativistic
non-ideal hydrodynamics, a still open issue connected to...
We present a local framework for investigating non-unitary evolution groups pertinent to effective field theories in general semi-classical spacetimes. Our approach is based on a rigorous local stability analysis of the algebra of observables and solely employs geometric concepts in the functional representation of quantum field theory. In this representation, it is possible to construct...
We consider a real, massive scalar field in the cosmic string spacetime. First, we determine all admissible boundary conditions that can be applied at the conical singularity, and we find that no "bound state" solutions exist under these conditions. Next, we construct the two-point function for the ground state that satisfies these boundary conditions, deriving an explicit closed-form...
I will present a novel approach to compute Hawking radiation based on on-shell scattering amplitudes.
Wireless communication between quantum systems can be modeled using a pair of Unruh-deWitt detectors interacting with a field in the background. Leveraging quantum properties, this approach could enhance the ability to send classical messages over distances and pave the way for transmitting quantum information. Motivated by these possibilities, we develop a quantum communication protocol using...
Investigating quantum mechanical principles within the context of gravity reveals significant insights into how spacetime curvature fundamentally influences quantum phenomena, particularly regarding the uncertainty principle and quantum coherence. This study presents a covariant Generalized Uncertainty Principle (GUP) that incorporates curvature-induced modifications to canonical commutation...
