The interference between amplitudes corresponding to different intermediate resonances plays an important role in generating large CP asymmetries in the phase space in multi-body decays of bottom and charmed mesons. In this study, we examine the CP violation in the decay channel $ {\overline{B}}^{0}\rightarrow K^{-}\pi^{+}\pi^{0} $ in the phase-space region where the intermediate resonances $ \overline{K}^{*}(892)^{0} $ and $ {\overline{K}^{*}_{0}(700)} $ dominate. In particular, the forward-backward asymmetry (FBA) and the CP asymmetry induced by FBA (FB-CPA), which are closely related to the interference effects between the two aforementioned resonances, are investigated. The nontrivial correlation between FBA and FB-CPA is analyzed. The analysis indicates that FB-CPAs around the resonance $ \overline{K}^{*}(892)^{0} $ can be as large as approximately 35%, which can be potentially accessible by Belle and Belle-II collaborations in the near future.

China

Jian-Yu Yang

Yu-Jie Zhao

Jing-Juan Qi

Zhen-Hua Zhang

The forward-backward asymmetry induced CP asymmetry in ${{\overline{B}}^{0}\rightarrow K^{-}\pi^{+}\pi^{0}}$ in phase space around the resonances ${{\overline{K}}^{*}(892)^{0}}$ and ${{\overline{K}}^{*}_{0}(700)}$ * Supported by National Natural Science Foundation of China (12475096, 12405115, 12192261) and Scientific Research Fund of Hunan Provincial Education Department (22A0319)

Motivated by the observation of the doubly charmed tetraquark $ T_{cc}(3875)^+ $ , we present a systematic study of doubly heavy tetraquarks ( $ T_{QQ'\bar{q}\bar{q}'} $ ) using heavy antiquark-diquark symmetry (HADS) within a constituent quark model. By calibrating model parameters to known hadron spectra and incorporating the effective mass formula, we predict the masses for 38 ground-state tetraquarks with $ cc $ , $ bb $ , and $ bc $ heavy quark pairs, including the non-strange, single-strange, and double-strange configurations with quantum numbers $ J^P = 0^+, 1^+ $ and $ 2^+ $ . Notably, we identify several stable states below the relevant meson-meson thresholds, particularly in the $ bb\bar{q}\bar{q}' $ sector. The explicit connection between the doubly heavy tetraquark and the heavy baryon spectra through HADS reduces model dependence and reveals the fundamental systematics in the heavy-quark hadron landscape.

Liu-Yu Zhang

Tian-Wei Wu

Yong-Liang Ma

Bridging doubly heavy tetraquark mass spectrum with heavy baryons utilizing heavy antiquark-diquark symmetry * The work of Tian-Wei Wu is supported by the National Natural Science Foundation of China (12405108). Yong-Liang Ma is supported in part by the National Science Foundation of China (NSFC) (12347103) and Gusu Talent Innovation Program (ZXL2024363)

The Schwinger effect, a non-perturbative mechanism for particle production in strong fields, plays a crucial role in understanding quantum vacuum decay and high-energy phenomena, including heavy-ion collisions (HIC). Although holographic quantum chromodynamics (QCD) models have been widely used to study this effect, most treatments assume isotropy or consider only a single type of anisotropy, neglecting the interplay between spatial and magnetic anisotropies that arise in realistic HIC scenarios. A unified framework accounting for both anisotropies is needed to accurately model particle production. We investigate the Schwinger effect in a twice anisotropic holographic QCD model incorporating both spatial and magnetic anisotropies. Using the anti-de Sitter/conformal field theory correspondence, we compute the total potential of a particle-antiparticle pair to quantify how these anisotropies influence pair production. Our results show that the magnetic field (parameterized by $c_B$ and $q_3$ ) enhances the Schwinger effect by lowering and narrowing the potential barrier, while increasing spatial anisotropy (controlled by $\nu$ ) suppresses the process by raising and widening the barrier. These findings demonstrate that magnetic and spatial anisotropies exert competing effects on particle production, emphasizing the necessity of treating both concurrently in holographic models. This work advances the theoretical description of the Schwinger effect in anisotropic environments, with implications for understanding non-equilibrium dynamics in HIC and other strongly coupled systems.

Wen-Bin Chang

Defu Hou

Schwinger effect in a twice anisotropic holographic model * Defu Hou's research is supported in part by the National Key Research and Development Program of China (2022YFA1604900). Additionally, Defu Hou receives partial support from the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Wen-Bin Chang is supported by the Ph.D. Research Startup Project at Hubei Minzu University (RZ2500000857)

We show that in an elliptic function based formulation for fields with large amplitudes, the rolling down of solitons towards the degenerate vacua can be described as transitions through local meta-stable potentials; the kink-like solitons constructed locally around the maxima of the potential will roll down into the vacua without changing their profiles and their energies, but amplifying their amplitudes and their topological charges. Furthermore, the cusp-like solitons trapped at vacua will admit a nonlinear decomposition in terms of fundamental solitons with different profiles, energies, amplitudes, and topological charges; a scale-probe is proposed in order to reveal the different scales for those vacuum fundamental solitons. The possibility for a vacuum-vacuum tunneling for solitons is addressed.

Mexico

R. Cartas-Fuentevilla

A. Herrera-Aguilar

M. Aguilar-Gonzalez

P. Fierro-Rojas

M. Roque-Vargas

D. Condado-Hernandez

J. Calvario-Acocal

U. Guerra-Franklin

Spontaneous symmetry breaking for solitons and local meta-stability: an elliptic functions based formulation

We perform a comparative phase space analysis of the light mass Galileon model and standard quintessence in the context of late-time cosmic acceleration. Focusing on a spatially flat FLRW background, we consider a cubic Galileon interaction supplemented by a scalar potential and examine three representative choices of the potential: a generalized cosh potential, a simple cosh potential, and a linear potential. By introducing suitable dimensionless variables, the cosmological field equations are reformulated as an autonomous dynamical system, allowing a systematic investigation of the stationary points and their stability properties. For the light mass Galileon scenario, we find that although the phase space admits scalar field dominated solutions, all critical points are of saddle type for the potentials considered. In particular, no stable late-time accelerating attractor emerges, even in the presence of de-Sitter like configurations. In contrast, the quintessence limit admits stable de-Sitter attractors for cosh potentials, providing a viable description of the observed late-time acceleration. Our results highlight a key qualitative distinction between Galileon and quintessence cosmologies and indicate that, within the light mass Galileon framework, the higher-order Galileon interactions may be required to realize a stable accelerating Universe.

Kazakhstan

India

Mohd Shahalam

Galileon versus quintessence: a comparative phase space analysis and late-time cosmic relevance

We investigate the temperature dependence of the shear viscosity (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi></math>) and bulk viscosity (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ζ</mi></math>) of the gluon plasma using lattice QCD over the range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0.76</mn><mo>−</mo><mn>2.25</mn><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math>, extending from below the transition temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math> across the transition region and into the deconfined phase. At each temperature, we employ three large, fine lattices, which enables controlled continuum extrapolations of the energy-momentum tensor correlators. Using gradient flow together with a recently developed blocking technique, we achieve percent-level precision for these correlators, providing strong constraints for a model-based spectral analysis. Since the inversion to real-time information is intrinsically ill posed, we extract viscosities by fitting spectral functions whose ultraviolet behavior is matched to the best available perturbative result, while the infrared region is described by a Lorentzian transport peak. The dominant modeling uncertainty associated with the transport peak width is bracketed by varying it over a physically motivated range set by thermal scales. We find that the shear-viscosity-to-entropy-density ratio, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>/</mo><mi>s</mi></math>, exhibits a minimum near the transition temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math> and increases for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi><mo>&gt;</mo><msub><mi>T</mi><mi>c</mi></msub></math>, whereas the bulk-viscosity-to-entropy-density ratio, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ζ</mi><mo>/</mo><mi>s</mi></math>, decreases monotonically over the entire temperature range studied.

Heng-Tong Ding

Hai-Tao Shu

Cheng Zhang

Shear and bulk viscosities of the gluon plasma across the transition temperature from lattice QCD

We discuss physics-informed renormalization group flows (PIRGs) for general operators. We show that operator PIRGs provide comprehensive access to all correlation functions of the quantum field theory under investigation. The operator PIRGs can be seen as a completion of the PIRG approach, whose qualitative computational simplification and structural insights are now fully accessible for general applications. The potential of this setup is assessed within a simple analytic example of the zero-dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>4</mn></msup></math>-theory, for which the generating functions of the fundamental field are computed within a vertex expansion, using the one- to ten-point functions.

Friederike Ihssen

Jan M. Pawlowski

Physics-informed operator flows and observables

We consider a spacetime singularity at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mo>=</mo><mn>0</mn></math> arising in a Kasner-type metric that solves the gravitational equations modified by quantum effects of a conformal field theory (CFT). The resulting constraints can be solved efficiently when expressed in terms of symmetric polynomials. Focusing first on the trace part of the modified gravitational equation, we determine the corresponding solution surfaces in the Kasner parameter space. The geometry of these surfaces depends sensitively on the ratio <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>=</mo><mi>A</mi><mo>/</mo><mi>C</mi></math>, the quotient of the conformal charges characterizing the underlying CFT. We then fully integrate the conformal anomaly near the singularity for a generic Kasner-type metric and obtain the corresponding stress-energy tensor. Its components are expressed in terms of three symmetric polynomials (of degrees 2, 3, and 4) and depend on seven arbitrary constants, which may be interpreted as parametrizing different choices of the quantum state at the singularity. By imposing a set of constraints, we reduce this parameter space to a single free constant. Subsequently, we solve, at leading order near the singularity, the modified gravitational equations. Among the admissible solutions, we identify, in particular, those that develop a curvature singularity while remaining geodesically complete.

Sergey N. Solodukhin

Cosmological singularity, conformal anomaly and symmetric polynomials

This review examines data from hadron-nucleus collisions, primarily focusing on hard processes like Drell-Yan, heavy flavor, and quarkonium production. It highlights observed modifications of particle yields as functions of momentum and rapidity, aiming to clarify the underlying QCD effects on cold nuclear matter. It outlines strategies for future experiments, including the Electron-Ion Collider, to distinguish between these effects. Key questions address the universality of suppression mechanisms and the role of nonperturbative physics, providing a road map for upcoming measurements of hadrons on nuclei.

F. Arleo

P. Caucal

A. Deshpande

J.M. Durham

G.M. Innocenti

J. Jalilian-Marian

A. Kusina

M.X. Liu

Y. Mehtar-Tani

C.J. Naïm

H. Paukkunen

S. Platchkov

F. Salazar

I. Vitev

R. Vogt

Nuclear cold QCD: Review and future strategy

In this paper, we investigate the quantum field theory in Klein space that has two time directions. To study the canonical quantization, we select the “length of time” <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>q</mi></math> as the evolution direction of the system. In our novel construction, some additional modes beyond the plane wave modes are crucial in the canonical quantization and the later derivation of the Lehmann-Symanzik-Zimmermann reduction formula. We also derive the free two-point function by using Wick contraction in the canonical quantization formalism. Moreover, we introduce the path-integral formalism in which we can redefine the vacuum states and rederive the correlation functions. We show that all the results in the Klein space derived in our novel approach match those obtained via analytical continuation from the Minkowski spacetime.

Bin Chen

Zezhou Hu

Xin-Cheng Mao

QFT in Klein space