To better understand recent predictions on the moat regime of quantum chromodynamics (QCD) matter, this paper extends the previous work within the two-flavor quark-meson (QM) model to the more realistic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo>+</mo><mn>1</mn></math> flavor Polyakov-quark-meson (PQM) model. Mainly, two effects are further taken into account: strange quark and confinement coded through Polyakov loop. Model parameters are chosen to consistently reproduce the pseudocritical temperature from lattice QCD, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi mathvariant="normal">C</mi></msub><mo>∼</mo><mn>156</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, and the baryon chemical potential at the critical end point (CEP) from functional renormalization group to QCD matter (FRG-QCD), <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>μ</mi></mrow><mrow><mi mathvariant="normal">B</mi></mrow></msub><mrow><mo stretchy="false">(</mo><mi>CEP</mi><mo stretchy="false">)</mo></mrow><mo>∼</mo><mn>635</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. It is found that the basic features of moat regimes for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> mesons remain similar to those from QM model: Moat regimes cover the region where temperature or baryon chemical potential is large; reentrances occur around the critical baryon chemical potential of chiral transition at zero temperature. Thus, the FRG-QCD results can still not be well understood, especially why the extrapolated CEP should be consistent with the boundaries of moat regimes for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math> mesons. Nevertheless, some basic features can be understood qualitatively, and it is consistent that the pole energies are increasing functions of momenta in the whole <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi><mo>−</mo><msub><mi>μ</mi><mi mathvariant="normal">B</mi></msub></math> plane. The moat regime and pole energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math> mesons are also studied with the features similar.

China

Gaoqing Cao

Moat regimes within a (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>)-flavor Polyakov-quark-meson model

The process of all-vortex nonlinear Compton scattering in an intense and polarized laser field, in which the initial and final electrons and the emitted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photon are all in vortex states, is studied theoretically. We develop a formalism for the process, which allows us to study the exchanges of the orbital angular momentum (OAM) and spin angular momentum among the electron, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photon, and laser. A wave packet of the Bessel-Gaussian type is adopted to describe the initial vortex electron for the purpose of normalization. Both circularly and linearly polarized lasers are examined. Substantial numerical calculations are performed to reveal the physics of the exchanges of the OAM and spin angular momentum. The strong impact of the laser intensity and the opening angle of the initial vortex electron is demonstrated. Our results also suggest possible scenarios for the separation of the emitted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math> photons with different OAMs, as well as a possible way which could help to distinguish the OAM and spin of the vortex particle by the multipeak structure in the spectrum of the emitted photon.

Yi Liao

Quan-Yu Wang

Yuanbin Wu

All-vortex nonlinear Compton scattering in a polarized laser field

In this paper, we present an innovative approach to resolving type IV singularities in fermionic quantum cosmology. The Eisenhart–Duval lift procedure is employed to construct an extended minisuperspace metric, which allows for the formulation of the Dirac equation in minisuperspace. Through this approach, fermionic degrees of freedom are effectively incorporated into a homogeneous and isotropic cosmological model with a scalar field. By applying a kind of the Born-Oppenheimer approximation, solutions to the Dirac equation for an approximate potential characteristic of type IV singularities are obtained, expressed in terms of Tricomi confluent hypergeometric functions and associated Laguerre polynomials. The elimination of non-physical, divergent solutions results in a quantum regularization of the classical singularity. These results indicate the potential of fermionic models in quantum cosmology for mitigating the singularity problem.

Poland

Paweł Kucharski

Adam Balcerzak

Fermionic quantum cosmology as a framework for resolving type IV singularities

We discuss recent approaches to the computation of black hole entropies through semiclassical estimates of appropriate state overlaps, saturated by Euclidean wormhole configurations. We notice that the relevant saddle-point manifolds may exhibit instabilities, thereby compromising the interpretation of the Euclidean path integral as a tool for computing positive-definite inner products. We show that a proper treatment using a microcanonical formulation effectively addresses the puzzles posed by these instabilities.

Spain

J. Barbón

E. Velasco-Aja

A note on black hole entropy and wormhole instabilities

In this work, we explore the feasibility of realizing the Dark Dimension Scenario through T-fold compactifications on $\textit{T}$ × $\textit{S}$ , where the base of the internal space $\textit{S}$ naturally acts as the requisite mesoscopic extra dimension. Utilizing Scherk-Schwarz reduction from 5D to 4D, and applying duality twists from both elliptic and parabolic conjugacy classes of subgroups of the T-duality group associated with $\textit{T}$ , we stabilize the volume of $\textit{T}$ and several other moduli. This approach generates a potential characterized by two runaway directions, one aligned with the Scherk-Schwarz radion. Further stabilization efforts yield a decreasing potential trajectory demanded by the Dark Dimension Scenario.

Netherlands

Guo-En Nian

Stefan Vandoren

Towards a string realization of the Dark Dimension via T-folds

We study the impact of thermal effects on gravity-induced entanglement (GIE) in a system of quantum harmonic oscillators interacting with classical linearly polarized gravitational waves (GWs). Specifically, we model the endpoints of interferometer arms in LIGO-like detectors as two-dimensional oscillators. Following the thermofield dynamics (TFD) approach, our analysis reveals that while thermal effects alone do not generate entanglement between independent oscillator modes, they serve as a catalyst, modifying the dynamical imprint of GWs. Notably, we identify a mixing of Bose-Einstein and Maxwell-Boltzmann distributions driven by thermal influences, which affects the statistical behavior of the quantum subsystem. Furthermore, gravitational interactions induce a quantum memory effect, leading to emergent periodic behavior in the reduced subsystem. This suggests a novel gravitationally induced breaking of time-translation symmetry, reminiscent of a prethermal time crystal (PTC). Our findings indicate that such effects could provide new theoretical insights into classical gravitational wave interactions.

India

Mainak Dutta

South Africa

Partha Nandi

Bibhas Majhi

Gravitationally induced entanglement at finite temperature: A memory-driven time-crystalline phase?

Functional methods can be applied to the quantum effective action to efficiently determine counterterms and matching conditions for effective field theories. We extend the toolbox to two-loop order and beyond and show how to evaluate the expansion of the path integral in a manifestly gauge-covariant manner. We also generalize the method to theories with mixed spin statistics and prove the validity of the hard-region matching formula to all loop orders. The methods are exemplified with a two-loop matching calculation of the Euler–Heisenberg Lagrangian resulting from decoupling the electron in QED.

Javier Fuentes-Martín

Adrián Moreno-Sánchez

Switzerland

Ajdin Palavrić

Anders Thomsen

A guide to functional methods beyond one-loop order

Parity-inverted anti-de Sitter space — “flipped AdS” — is studied through the accelerating boundary correspondence of a moving mirror trajectory. The particle production exhibits positive energy flux and a finite total energy (unlike AdS and de Sitter respectively). The particle spectrum is of Whittaker form, with some similarities to a Planck thermal spectrum. We also derive the corresponding spacetime metric, with similarities to regular de Sitter space, but exhibiting a tower of repeated causal regions with horizons.

Taiwan

United States

Kazakhstan

Michael Good

Eric Linder

Through the looking-glass, and what AdS found there: quantum particle production with a Whittaker spectrum

Diffusion wake accompanying a Mach cone is a unique feature of the medium response to projectiles traveling at a speed faster than the velocity of sound. This is also the case for jet-medium interaction inside the quark-gluon plasma in high-energy heavy-ion collisions. It leads to a depletion of soft hadrons in the opposite direction of the propagating jet and, recently, has been observed in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>Z</mi></mrow></math>-jet events of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at LHC. In dijet events, however, the diffusion wake of one jet usually overlaps with the medium-induced hadron enhancement of the other jet without a clear signal except a reduction of the hadron enhancement, unless there is a large rapidity gap between the two jets. We propose to use the rapidity asymmetry of jet-hadron correlations in dijets with a finite rapidity gap relative to that without, as a robust and background-free signal of the diffusion wake. The asymmetry emerges because the diffusion wake of one jet is shifted to a finite rapidity relative to the other jet. Consequently, a depletion of soft hadrons appears in the shifted rapidity region of the diffusion wake and an enhancement in the rapidity region of the other jet whose soft hadron enhancement is no longer or less reduced by the diffusion wake as in dijets without a rapidity gap. We predict the rapidity asymmetry using both theoretical and mixed-event background subtraction for different values of the rapidity gap within the CoLBT-hydro model. Future measurements of this rapidity asymmetry with high statistics data on dijets should provide more precise insights into the jet-induced diffusion wake and properties of the quark-gluon plasma.

Zhong Yang

Xin-Nian Wang

Rapidity Asymmetry of Jet-Hadron Correlation as a Robust Signal of Diffusion Wake Induced by Dijets in High-Energy Heavy-Ion Collisions

We present a method for obtaining an initial-state parton shower model where the (backward) evolution fully consistent with the (forward) evolution of the collinear parton density used. As a proof-of-concept we use parton densities obtained with the parton branching (PB) approach, and modify the default initial-state shower in 8 with this method to be consistent with them. PB is ideally suited for checking the validity of our method since, in addition to producing collinear parton densities, it also produces the corresponding transverse-dependent (TMD) ones, and these can then be directly compared to the transverse momentum distribution obtained from the parton shower. We show that TMD distributions which we in this way obtain from our modified 8 shower using leading order (LO) parton densities and splitting functions are fully consistent with the corresponding leading order TMD densities. At next-to-leading order (NLO) it is not possible to achieve the same consistency using the built-in LO splitting functions in the shower, but we show that by introducing NLO splitting functions using a reweighting procedure, we can achieve consistency also at NLO. The method presented here, which we have named , can be easily extended to any collinear parton densities, as long as the exact conditions for the evolution are known. With the method we obtain an initial-state parton shower which in principle has no free parameters, and is fully consistent with collinear parton densities at LO and NLO.