We investigated the effect of an isospin chemical potential ( $ \mu_{I} $ ) within the quark-meson model, which approximates quantum chromodynamics (QCD) by modeling low-energy phenomena such as chiral symmetry breaking and phase structure under varying conditions of temperature and chemical potential. Using the functional renormalization group (FRG) flow equations, we calculated the phase diagram in the chiral limit within the two-flavor quark-meson model in a finite $ \mu_{I} $ with $\textit{ρ}$ vector meson interactions. Fluctuation effects significantly decrease the critical chemical potential from the mean-field (MF) value $\mu_{I,{\rm MF}} \gt m_\rho$ to a lower value at which the $\textit{ρ}$ vector meson condensates alongside the chiral condensate once the isospin chemical potential exceeds the critical value $ \mu_{I}^{{\rm{crit}}} $ . This $\textit{ρ}$ condensation was investigated numerically for different meson coupling strengths. The $\textit{ρ}$ meson dominated region is delineated from other phases by a second-order phase transition at lower $ \mu_{I} $ and a first-order transition at slightly higher $ \mu_{I} $ .

China

Mohammed Osman

Defu Hou

Wentao Wang

United States

Hui Zhang

Functional renormalization group study of $\textit{ρ}$ meson condensate at a finite isospin chemical potential in the quark meson model * Supported in part by the National Key Research and Development Program of China (2022YFA1604900). This work is also partly supported by the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Hui Zhang acknowledges the financial support from the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008) and the National Natural Science Foundation of China (12047523, 12105107)

In this study, we investigate a scenario based on the effects of the Loop Quantum Gravity (LQG) on the electromagnetic sector of the Standard Model of Fundamental Interactions and Particle Physics (SM). Starting from a post-Maxwellian version of electromagnetism that includes LQG effects, we derive and discuss the influence of LQG parameters on classical quantities such as the components of the stress-tensor. Furthermore, we inspect the propagation of electromagnetic waves and examine the optical properties of the QED vacuum in this scenario. Among these, we contemplate the combined effect of the LQG parameters and a homogeneous background magnetic field on the propagation of electromagnetic waves by considering issues such as group velocities and refractive indices of the QED vacuum, in detail. Finally, with the aid of the previously analyzed LQG-extended photonic dispersion relations, we re-discuss the kinematics of the Compton effect and conclude that an interesting nonlinear profile emerges in the wavelengths of the incoming and deflected photons.

Brazil

P.A.L. Mourão

G.L.L.W. Levy

J.A. Helayël-Neto

Reassessing aspects of LQG-modified dispersion relations of photons * P. A. L. Mourão is support by CAPES. G. L. L. W. L. Levy is support by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Grant No. E-26/202.437/2024.

Several possible excesses around $ 95 $ GeV hint at an additional light scalar beyond the Standard Model. We examine the capability of the Circular Electron-Positron Collider (CEPC) to test this hypothesis in the Higgs-strahlung channel $ e^{+}e^{-} \to ZS $ with $ Z \to\mu^{+}\mu^{-} $ and $ S \to\tau^{+}\tau^{-} $ . A full detector simulation shows that the optimal center-of-mass energy for studying the 95 GeV light scalar is 210 GeV. A deep neural network classifier reduces the luminosity required for discovery by half. At $ L = 20\; \mathrm{ab}^{-1} $ , the $ 5\sigma $ sensitivity of the CEPC to the signal strength $ \mu_{\tau\tau}^{ZS} $ reaches 0.016 and 0.020 for $ \sqrt{s} = 210 $ GeV and 240 GeV, respectively. The corresponding thresholds for a 5% precision measurement are $ \mu_{\tau\tau}^{ZS} \gt 0.10 $ and $ \gt 0.12 $ . At $ \sqrt{s}=210 $ GeV (240 GeV), the $ 5\sigma $ coverage of all N2HDM-Flipped samples with $ \chi^2_{h_{95}} \lt 7.82 $ requires $ L=800\ \mathrm{fb}^{-1} $ (1.22 $ \mathrm{ab}^{-1} $ ). These results establish a 210 GeV run, augmented by machine-learning selection, as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.

Yabo Dong

Manqi Ruan

Kun Wang

Haijun Yang

Jingya Zhu

Testing a 95 GeV Scalar at the CEPC with Machine Learning * This work was supported by the National Natural Science Foundation of China under Grant No. 12275066 and by the startup research funds of Henan University. The work of K. Wang was also supported by the Open Project of the Shanghai Key Laboratory of Particle Physics and Cosmology under Grant No. 22DZ2229013-3. The work of M. Ruan was also supported by the National Key Program for S&T Research and Development under Contract No. 2024YFA1610603. The work of H. Yang was also supported by the National Natural Science Foundation of China under Grant No. W2441004.

A model for the nuclear medium modification of parton densities is presented. The approach is based on a global analysis of available deep inelastic scattering data for different nuclear targets within the rescaling model, combined with the effects of Fermi motion. The scale dependence is implemented through the DGLAP-evolved quark and gluon densities in a proton derived analytically at the leading order of QCD coupling. By fitting the rescaling parameters to experimental data on the ratio $F_2^A(x,Q^2)/F_2^{A^\prime}(x,Q^2) $ for several nuclear targets $\textit{A}$ and $\textit{A}$', we obtain predictions for nuclear parton distributions, even for unmeasured nuclei. The effects of nuclear modifications are investigated with respect to the mass number $\textit{A}$. We highlight distinct shadowing and antishadowing behaviors for gluons and quarks.

Russia

A.V. Kotikov

A.V. Lipatov

A simple model for nuclear modification of parton distribution functions * This research has been carried out at the expense of the Russian Science Foundation grant 25-22-00066, https://rscf.ru/en/project/25-22-00066/

We investigate the discovery prospects of a leptophilic gauge boson $ Z_\ell $ at future $ e^+e^- $ colliders, focusing on a comparative study of the Circular Electron–Positron Collider (CEPC) and the International Linear Collider (ILC). Such a state naturally arises from an additional $ U(1)'_\ell $ gauge symmetry, under which quarks remain neutral while all leptons carry a universal charge, motivated by neutrino oscillations and scenarios of physics beyond the Standard Model. As a clean benchmark, we study the process $ e^+e^- \to \mu^+\mu^- $ , including realistic effects of initial-state radiation and beamstrahlung. Our results indicate that the CEPC, with its very high luminosity at $ \sqrt{s}=240 $ GeV, can probe couplings down to $ g_\ell \approx 10^{-3} $ for $ Z_\ell $ masses up to about 220 GeV. The ILC extends the sensitivity to heavier states in the multi-hundred GeV range through its higher $ \sqrt{s} $ stages. These findings demonstrate the strong complementarity of circular and linear colliders in exploring purely leptophilic interactions.

S.O. Kara

Discovery prospects for a leptophilic gauge boson Z$_{ℓ}$ at CEPC and ILC

An analytical and numerical systematic study of the neutrino mass matrix with one texture zero is presented in a basis where the charged leptons are diagonal. Under the assumption that neutrinos are Dirac particles, the analysis is conducted in detail for the normal and inverted hierarchy mass spectra. Our study is performed without any approximations, first analytically and then numerically, using current neutrino oscillation data. The analysis constrains the parameter space in such a way that, among the six possible one-texture-zero patterns, only four are favored in the normal hierarchy and one in the inverted hierarchy by current oscillation data at the $3 \sigma$ level. Phenomenological implications for the lepton CP-violating phase and neutrino masses are also explored.

Colombia

Richard H. Benavides

Yessica Lenis

John D. Gómez

William A. Ponce

One texture zero for Dirac neutrinos in a diagonal charged lepton basis * Richard H. Benavides acknowledges additional financial support from Minciencias (CD82315 CT ICETEX 2021-1080)

Heavy Majorana neutrinos ($\textit{N}$) are predicted in many models of physics beyond the Standard Model. In this work, we explore the production and detection prospects of TeV-scale heavy neutrinos ( $ m_N \gtrsim 1 $ TeV) at a future 3 TeV Compact Linear Collider (CLIC). We focus on two distinct decay topologies: (i) $ N \to \ell^\pm W^\mp $ with hadronic $\textit{W}$ boson decay, leading to a final state with one charged lepton and a hadronic fat jet $ J_W $ ; and (ii) $ N \to \nu h $ with subsequent Higgs decay $ h \to b\bar{b} $ , yielding a Higgs-tagged fat jet $ J_h $ and $\not {E}_T$ . Based on comprehensive detector-level simulations and background analysis, we present both $ 2\sigma $ exclusion limits and $ 5\sigma $ discovery reaches in the $ m_N $ – $ |V_{\ell N}|^2 $ plane. We further extract 95% confidence level upper limits on the mixing parameter $ |V_{\ell N}|^2 $ and perform a detailed comparison with existing constraints from direct searches at future colliders and indirect global fits. Our findings demonstrate that a 3 TeV CLIC can improve the sensitivity to $ |V_{\ell N}|^2 $ by about two orders of magnitude compared with the projected reaches of future hadron colliders while remaining competitive with other CLIC search channels.

Yao-Bei Liu

Jing-Wei Lian

Searches for heavy neutrinos at a 3 TeV CLIC in fat jet final states * Yao-Bei Liu is supported by the Natural Science Foundation of Henan Province, China (252300421988), Jing-Wei Lian is supported by the National Natural Science Foundation of China (12447140) and the Natural Science Foundation of Henan Province, China (252300421771)

We investigate the geometric and physical properties of an anti-de Sitter (AdS) black hole (BH) space-time coupled by a cloud of strings (CoS) and surrounded by a quintessence-like fluid (QF), all within the framework of non-commutative (NC) geometry. From the perspective of geometrical optics, we analyze the behavior of null geodesics, focusing on key optical features such as the effective potential, the structure and radius of the photon sphere, photon trajectories, and the resulting BH shadow. Our findings show that the combined effects of CoS and QF significantly modify photon dynamics and optical observables, leading to notable deviations from standard BH scenarios in NC geometry background. We also examine time-like geodesics, with particular emphasis on the innermost stable circular orbits (ISCOs). The results demonstrate that the presence of geometric and physical parameters alters the ISCO radius compared to conventional solutions. In addition, we explore the thermodynamic behavior of the BH solution, deriving key expressions, such as the Hawking temperature, entropy, Gibbs free energy, and specific heat capacity. The factors CoS and QF introduces substantial modifications to the thermodynamic profile, including shifts in phase transition points and changes to stability conditions under NC geometric effects. Furthermore, we study the dynamics of massless scalar field perturbations in this modified background by formulating the Klein–Gordon equation and reducing it to a Schrödinger-like form via separation of variables. The effective potential shows how CoS and QF shape perturbations in NC geometry background. Finally, we compute the quasinormal modes (QNMs) spectra by varying these parameters using the WKB method.

India

Faizuddin Ahmed

Allan Moreira

Algeria

Abdelmalek Bouzenada

Noncommutative geometry inspired AdS black hole with a cloud of strings surrounded by quintessence-like fluid

<p>The method of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Q</mi></mrow></math> cumulants has been shown as a powerful tool to study the fine details of the azimuthal anisotropies in high-energy nucleus-nucleus collisions. A new method for the fast calculation of arbitrary order <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Q</mi></mrow></math>-cumulant <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>v</mi><mi>n</mi></msub><mrow><mo>{</mo><mn>2</mn><mi>k</mi><mo>}</mo></mrow></mrow></math> values, based on the partition of a non-negative integer <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>l</mi><mo>≤</mo><mi>m</mi></mrow></math> for calculation of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>2</mn><mi>m</mi></mrow></math>-particle azimuthal correlations is presented in this paper. Unlike the standard <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Q</mi></mrow></math>-cumulants method in which the calculation of high-order multiparticle calculations is impractical, the newly proposed method enables easy calculation. The validity of the method is proven via a toy model that uses the elliptic power distribution to simulate anisotropic emission of particles. The method enables the study of fine details of the <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub></math> distribution, such as higher-order central moments of the <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub></math> distribution, as well as the hydrodynamic behavior of the quark-gluon plasma.</p>

Serbia

L. Nađđerđ

J. Milošević

D. Devetak

F. Wang

X. Zhu

Novel approach to a fast calculation of high-order <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Q</mi></mrow></math> cumulants

<p>We present a theoretical investigation of the radiative decay process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>γ</mi><mi mathvariant="normal">Ω</mi></math>, where the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo></math> resonance with spin-parity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>−</mo></msup></math> is treated as a dynamically generated state from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mi mathvariant="normal">Ω</mi></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-wave and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mi mathvariant="normal">Ξ</mi></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>-wave. The radiative decay width of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo></math> is calculated using a triangular loop mechanism, where the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo></math> couples to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><mo stretchy="false">)</mo></math> channel. Subsequently, the final-state interactions between <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover></math> transition to a photon and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi></math> through the exchange of a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ξ</mi></math> baryon. Our calculations yield a radiative decay width of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mn>13.2</mn></mrow><mrow><mo>−</mo><mn>5.6</mn></mrow><mrow><mo>+</mo><mn>4.5</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><mi>keV</mi></mrow></math>, with uncertainties arising from the model parameters. This result provides valuable insights into the nature of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo></math> resonance and its decay dynamics. It is expected that the calculations presented here could be verified by future experiments, which would open a new door for studying the still elusive nature of Ω(2012).</p>

Qing-Hua Shen

Jun-Xu Lu

Li-Sheng Geng

Xiang Liu

Ju-Jun Xie

Radiative decays of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Ω</mi><mo stretchy="false">(</mo><mn>2012</mn><mo stretchy="false">)</mo></math> as a hadronic molecule