In order to ensure measurement of the integrated luminosity with a relative precision of <inline-formula><tex-math id='TM0001' notation='LaTeX'>$\mathrm{10^{-4}}$</tex-math></inline-formula> at the <inline-formula><tex-math id='TM0002' notation='LaTeX'>$\mathrm{Z^{0}}$</tex-math></inline-formula> pole at the Circular Electron Positron Collider (CEPC), numerous systematic effects have to be quantified and, if possible, corrected for. Here we discuss the collective impact of electromagnetic bunch fields on the initial-state electrons and positrons (EMD1) as well as on the Bhabha scattering final states (EMD2). Both effects change the four-momenta of the final-state particles, leading to modification of the Bhabha count in the luminometer. These effects are quantified in a simulation, together with their stability with respect to beam parameter variations. Possible correction methods based on experimental measurements with the CEPC detector are discussed on a conceptual level.

Serbia

Ivan Smiljanić

Ivanka Božović

Ivana Vidaković

Nataša Vukašinović

Goran Kačarević

Electromagnetic Deflection Effects in the Integrated Luminosity Measurement at the CEPC

With the discovery of nonzero <inline-formula><tex-math id='TM0002' notation='LaTeX'>$\theta _{13}$</tex-math></inline-formula> and a near-maximal value of the Dirac CP phase as reflected from the measurements of the T2K and NO <inline-formula><tex-math id='TM0003' notation='LaTeX'>$\nu$</tex-math></inline-formula>A experiments, the significance of <inline-formula><tex-math id='TM0004' notation='LaTeX'>$\mu \text{-} \tau$</tex-math></inline-formula> reflection symmetry becomes more prominent. In this work, we study the renormalization group (RG) running effects on neutrino parameters as a perturbation to <inline-formula><tex-math id='TM0005' notation='LaTeX'>$\mu \text{-} \tau$</tex-math></inline-formula> reflection symmetry. Assuming the symmetry to be exact at the seesaw scale, we account the deviations of the parameters at the electroweak scale due to RG running. We solve numerically a set of 19 one-loop RG equations in total, including those of neutrino mixing parameters, mass eigenvalues, and gauge and Yukawa couplings, using a top-down approach. We aim to examine the consistency of the low-energy solutions at the EW scale with the observational data. Working in the Minimal Supersymmetric Standard Model framework, we choose three benchmark values at <inline-formula><tex-math id='TM0006' notation='LaTeX'>$1\ \text{TeV},\ 7\ \text{TeV}$</tex-math></inline-formula>, and <inline-formula><tex-math id='TM0007' notation='LaTeX'>$14\ \text{TeV}$</tex-math></inline-formula> for the supersymmetry breaking scale intermediate between the seesaw scale and EW scale. This requires a two-step running procedure to solve the RG equations and it also allows us to study the impact of variation of the supersymmetry breaking scale on the running effects. Our numerical results indicate that the deviations from <inline-formula><tex-math id='TM0008' notation='LaTeX'>$\mu \text{-} \tau$</tex-math></inline-formula> reflection symmetry induced by RG running remain compatible with the current <inline-formula><tex-math id='TM0009' notation='LaTeX'>$3\sigma$</tex-math></inline-formula> global oscillation data.

India

Chandan Kumar Borah

Chandan Duarah

Perturbations to <italic>&#956;-&#964;</italic> Reflection Symmetry Due to Renormalization Group Running Effects

We propose gauge-invariant criteria for center-vortex condensation and monopole condensation using the <inline-formula><tex-math id='TM0001' notation='LaTeX'>$\mathbb {Z}_N^{[1]}$</tex-math></inline-formula>-symmetry twisted partition functions: the torus twisted partition function characterizes the center-vortex condensation, and the lens-space twisted partition function characterizes the monopole condensation. To justify our proposal, we study how these twisted partition functions behave in the adjoint Higgs phase and show that their leading nontrivial contributions come from the center vortex and monopole, respectively. Using the techniques of topological field theories, we uncover the relationship between the center-vortex and monopole condensations, and, in particular, we prove that the gapped phase with the center-vortex condensation necessarily shows the monopole condensation, too. We then study a center-vortex model with monopoles as an illustrative example, and the higher-charge monopole condensation gives an example of symmetry fractionalization, which goes beyond the conventional Wilson&#8211;&#8217;t Hooft classification.

Japan

Yui Hayashi

Yuya Tanizaki

Monopoles, Center Vortices, Confinement in (3+1)D, and the Lens-Space Twisted Partition Function

In this work, we present a new construction of black hole solutions in noncommutative (NC) gauge theory by applying the Seiberg–Witten map directly to interaction potentials before solving Einstein’s equations. This approach provides a dynamical effect of space-time noncommutativity that preserves gauge covariance. We obtain both NC Schwarzschild and charged Reissner–Nordström-like black hole solutions, showing that the charged sector exhibits a novel branch dependence between attractive and repulsive electric interactions absent in the commutative limit. We analyze the geometrical properties, energy conditions, and thermodynamic properties of these space-times. Our results reveal that noncommutativity eliminates the temperature divergence at the final evaporation stage, inducing a second-order phase transition, or a Hawking–Page-like phase transition in the presence of pressure. Additionally, linear response analysis indicates high sensitivity to the NC parameter for small black holes. Finally, quantum tunneling investigations for both thermal and nonthermal radiation demonstrate that the NC deformation suppresses the particle-number density and weakens correlations between successive emissions, acting as a barrier to particle escape, and supports the formation of a cold finite remnant. From a cosmological standpoint, since these stable remnants possess a fixed Planck-scale mass ( <inline-formula><tex-math id='TM0001' notation='LaTeX'>$M^{\text{min}}\simeq 2.73 M_{P}$</tex-math></inline-formula>), they provide a dynamically generated, purely gravitational cold dark matter candidate that aligns with dark universe phenomenology while simultaneously resolving the black hole information loss paradox.

Algeria

Abdellah Touati

New Construction of Black Hole Solutions in Noncommutative Geometry and Their Thermodynamic Properties

Recent claims have suggested the absence of CP violation in theories with a <italic>&#952;</italic>-vacuum structure, particularly in quantum chromodynamics. We highlight several key points, from a perspective that is not widely discussed in the literature, which clarify why such conclusions are incorrect. In particular, an open boundary in a finite-volume theory must be accompanied by boundary degrees of freedom, the edge modes, in order to preserve large gauge invariance and faithfully capture the topological features of the theory. In the infinite-volume limit, these edge states become nondynamical, leaving the standard <italic>&#952;</italic>-vacuum structure intact, irrespective of whether this limit is taken before or after summing over topological sectors. Consequently, the <italic>&#952;</italic>-vacuum structure does give rise to observable CP violation once the theory is consistently quantized.

Australia

Archil Kobakhidze

On the <italic>&#952;</italic>-Vacua and CP Violation

In this paper, we study the quasinormal modes (QNMs) of a charged black hole in the presence of both quintessence and a cloud of strings using the Padé-averaged higher-order Wentzel–Kramers–Brillouin approximation method. We investigate the effect of the quintessence parameter <inline-formula><tex-math id='TM0001' notation='LaTeX'>$\alpha$</tex-math></inline-formula> and the cloud of strings parameter <inline-formula><tex-math id='TM0002' notation='LaTeX'>$\lambda$</tex-math></inline-formula> on stability as well as on the oscillation frequency of perturbations. The validity of Hod&#8217;s conjecture, which relates quasinormal frequencies to the black hole temperature, is tested throughout the physically allowed parameter space. Our results show that both the effective potential and the decay rate of perturbations depend on the values of <inline-formula><tex-math id='TM0003' notation='LaTeX'>$\alpha$</tex-math></inline-formula> and <inline-formula><tex-math id='TM0004' notation='LaTeX'>$\lambda ,$</tex-math></inline-formula> leading to either enhancement or suppression of the conditions required to satisfy Hod&#8217;s bound. Furthermore, we discuss how these parameters modify the black hole shadow and the corresponding energy emission rate, proving correlations with observable signatures. Finally, we establish the connection with the Swampland distance conjecture by expressing the Hawking temperature in terms of the scalar field excursion. Our analysis leads to a modified Hod bound and identifies a region of parameter space in which both the modified Hod bound and the Swampland constraints are simultaneously satisfied, ensuring consistency between black hole thermodynamics, observational properties, and quantum gravity constraints.

Morocco

S Saoud

M A Rbah

R Sammani

E H Saidi

R Ahl Laamara

A Swampland-Modified Hod Bound for Charged Black Holes with Exotic Matter

Understanding the phases of quantum chromodynamics (QCD) at finite temperature and baryon density is crucial for describing matter in heavy-ion collisions and the interior of neutron stars. While the transition from the confined phase to the deconfined phase has been extensively studied at vanishing chemical potential, recent theoretical work suggests the existence of intermediate phases with partial deconfinement, where only a subset of the color degrees of freedom is deconfined. In this paper, we study the generalization of partial deconfinement in QCD in the Veneziano large- <inline-formula><tex-math id='TM0001' notation='LaTeX'>$N_{\rm c}$</tex-math></inline-formula> limit ( <inline-formula><tex-math id='TM0002' notation='LaTeX'>$N_{\rm f}/N_{\rm c}$</tex-math></inline-formula> fixed) to a finite baryon chemical potential. We find that the partially deconfined phase has a finer structure, and hence that there are four phases in QCD at finite temperature and moderately large chemical potential: complete confinement, complete deconfinement, and two kinds of partial deconfinement. A key ingredient is the refined understanding of the meaning of the 'Gross&#8211;Witten&#8211;Wadia point', i.e. the opening of a gap in the distribution of Polyakov line phases: either string condensation or baryon condensation causes the GWW transition. As a by-product, we observe the emergence of the QCD critical point from the interplay between baryon condensation and partial deconfinement. While our approach is necessarily qualitative owing to the fermion sign problem, it provides a unified theoretical framework for understanding the rich phase structure of dense QCD matter and offers new perspectives on the location and nature of the QCD critical point.

United Kingdom

Masanori Hanada

China

Jack Holden

Hiromasa Watanabe

New Phases in QCD at Finite Temperature and Chemical Potential

Pole skipping is a universal property of Green’s functions at the strong coupling found in the AdS/CFT duality. There is a conventional formalism of pole skipping, but it relies on the existence of a “master variable.” Namely, it is applicable to a system with a single field. We propose an alternative formalism that does not rely on a master variable. As an example, we study the pole skipping of holographic superfluids. A “hydrodynamic” pole such as the diffusion pole is usually regarded as a pole-skipping point. But we point out that not all hydrodynamic poles are pole-skipping points because their residues may not vanish.

Makoto Natsuume

Takashi Okamura

Pole Skipping Without a Master Variable and Holographic Superfluids

We study the phase transitions of the 2D antiferromagnetic Ising model with nearest <inline-formula><tex-math id='TM0001' notation='LaTeX'>$J_1$</tex-math></inline-formula> and next-to-nearest <inline-formula><tex-math id='TM0002' notation='LaTeX'>$J_2$</tex-math></inline-formula> interactions on the triangular lattice for <inline-formula><tex-math id='TM0003' notation='LaTeX'>$J_2/J_1 = 0.1, 0.5$</tex-math></inline-formula>, and 1.0. The method of supervised neural networks (NNs) is employed for the investigation. Although supervised NN is used, no real spin configurations are needed for the training. In addition, two kinds of configurations which have their spins arranged in a staggered pattern are considered as the training set. Remarkably, with this unconventional training strategy, not only are the critical temperatures of the studied <inline-formula><tex-math id='TM0004' notation='LaTeX'>$J_2/J_1$</tex-math></inline-formula> computed accurately by the resulting NN, but also the nature of the investigated phase transitions is determined correctly. Specifically, the phase transitions associated with <inline-formula><tex-math id='TM0005' notation='LaTeX'>$J_2/J_1 = 0.1, 0.5$</tex-math></inline-formula>, and 1.0 are first order. These conclusions are consistent with the known results obtained by other methods. Since the training strategy is simple, the NN calculations are highly efficient. It remains to be examined whether the unconventional training approach considered in this study can be used to investigate other models with untypical phase transitions or with nontrivial ground-state configurations.

Taiwan

Shang-Wei Li

Yuan-Heng Tseng

Kai-Wei Huang

Fu-Jiun Jiang

A Machine Learning Study of the 2D Antiferromagnetic Ising Model with Nearest and Next-to-Nearest Interactions on the Triangular Lattice

The type IIB matrix model is expected to give a nonperturbative formulation of superstring theory. Its covariant derivative interpretation provides a method to describe curved spacetimes in the model. There, matrices are identified with certain covariant derivatives that can be viewed as infinite-size matrices. Here, by using the Berezin–Toeplitz quantization, we develop a method to regularize these matrices as finite-size ones, which is needed to calculate quantum effects in the interpretation, or in particular to apply the interpretation to the results of numerical simulations. As examples, we examine the cases of <italic>T</italic> <sup>2<italic>n</italic></sup> and <italic>S</italic> <sup>2</sup> in detail.

Keiichiro Hattori

Tatsuya Seko

Asato Tsuchiya

Description of Curved Spacetimes by Finite-Size Matrices in the Type IIB Matrix Model