Using <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>(</mo><mn>1.0087</mn><mo>±</mo><mn>0.0044</mn><mo>)</mo></mrow><mo>×</mo><msup><mn>10</mn><mn>10</mn></msup></mrow><mo> </mo><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> events collected with the BESIII detector at the BEPCII storage ring, the reactions <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mi>n</mi><mo>→</mo><mi mathvariant="normal">Λ</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mi>n</mi><mo>→</mo><msup><mi mathvariant="normal">Σ</mi><mn>0</mn></msup><mi>p</mi></mrow></math> are studied, where the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup></math> baryon is produced in the process <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>→</mo><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><msup><mover accent="true"><mi mathvariant="normal">Σ</mi><mo>¯</mo></mover><mo>−</mo></msup></mrow></math> and the neutron is a component of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mmultiscripts><mi>Be</mi><mprescripts></mprescripts><none></none><mn>9</mn></mmultiscripts><mo>,</mo><mo> </mo><mmultiscripts><mi mathvariant="normal">C</mi><mprescripts></mprescripts><none></none><mn>12</mn></mmultiscripts></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mmultiscripts><mi>Au</mi><mprescripts></mprescripts><none></none><mn>197</mn></mmultiscripts></math> nuclei in the beam pipe. Clear signals of these two reactions are observed for the first time. Their cross sections are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>σ</mi><mrow><mo>(</mo><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mo>+</mo><mmultiscripts><mi>Be</mi><mprescripts></mprescripts><none></none><mn>9</mn></mmultiscripts><mo>→</mo><mi mathvariant="normal">Λ</mi><mo>+</mo><mi>p</mi><mo>+</mo><mi>X</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>(</mo><mn>45.2</mn><mo>±</mo><mn>12</mn><mo>.</mo><msub><mn>1</mn><mi>stat</mi></msub><mo>±</mo><mn>7</mn><mo>.</mo><msub><mn>2</mn><mi>sys</mi></msub><mo>)</mo></mrow></mrow></math> mb and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>σ</mi><mrow><mo>(</mo><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mo>+</mo><mmultiscripts><mi>Be</mi><mprescripts></mprescripts><none></none><mn>9</mn></mmultiscripts><mo>→</mo><msup><mi mathvariant="normal">Σ</mi><mn>0</mn></msup><mo>+</mo><mi>p</mi><mo>+</mo><mi>X</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>(</mo><mn>29.8</mn><mo>±</mo><mn>9</mn><mo>.</mo><msub><mn>7</mn><mi>stat</mi></msub><mo>±</mo><mn>6</mn><mo>.</mo><msub><mn>9</mn><mi>sys</mi></msub><mo>)</mo></mrow></mrow></math> mb for a <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup></math> average momentum of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>0.992</mn><mspace width="0.28em"></mspace><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math>, within a range of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>±</mo><mn>0.015</mn><mspace width="0.28em"></mspace><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>X</mi></math> represents the residual nucleus. This is the first study of <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup></math>-nucleon scattering at an electron-positron collider. The measured results serve as a significant element in enhancing the comprehensive understanding of hyperon-nucleon interactions, and also constitute an important factor in resolving the “hyperon puzzle” of neutron stars.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Germany

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

United States

R.A. Briere

A. Brueggemann

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

Z.K. Chen

South Korea

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

Y.X. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

Y.T. Feng

M. Fritsch

C.D. Fu

J.L. Fu

First measurement of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mi>n</mi><mo>→</mo><mi mathvariant="normal">Λ</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup><mi>n</mi><mo>→</mo><msup><mi mathvariant="normal">Σ</mi><mn>0</mn></msup><mi>p</mi></mrow></math> cross sections via <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi mathvariant="normal">Σ</mi><mo>+</mo></msup></math>-nucleus scattering at an electron-positron collider

We study the QCD axion arising from the 5th component of a bulk U(1) gauge field in a five-dimensional warped grand unified theory, and determine the viable range of the axion decay constant $\textit{f}$ . Unlike flat extra dimensions, where gauge couplings run quickly above the Kaluza-Klein (KK) scale, the logarithmic running in warped geometries permits substantially smaller $\textit{f}$ while preserving perturbative gauge coupling unification. However, bulk tree-level contributions to the gauge coupling — interpreted holographically as CFT renormalization — place a lower bound on $\textit{f}$ . We find that the conventional QCD axion window 10 GeV ≲ $\textit{f}$ ≲ 10 GeV is readily compatible without losing perturbativity, provided the AdS curvature is near the Planck scale. Thus, the 5D warped orbifold GUT naturally accommodates a high-quality QCD axion in a grand unified theory that provides an effective description of string-theoretic warped flux compactifications, admitting complementary geometric and holographic descriptions of the axion.

Gongjun Choi

Tony Gherghetta

An extra-dimensional axion in a 5D warped orbifold GUT

We consider holographic entanglement entropy in AdS black hole backgrounds by using the limit of large number of dimensions. By dividing the geometry to two patches (with one patch covering the vicinity of the black hole horizon and another covering the other regions), we are able to obtain fully analytic expressions for the entropy when the entanglement region is a strip. We argue that apart from conformal field theories at finite temperature in high number of dimensions, our method works for nearly critical theories in 3+1 dimensions. In the case of extremal black holes, dual to quantum critical systems, the results take a particularly simple form. We also comment on the case of soliton geometries. Finally, we analyze entanglement entropy for wide strips, and propose a general formula for the first subleading term in the expansion of the entropy in (inverse) system size for generic entanglement regions.

India

Parul Jain

Matti Järvinen

An analytic approach for holographic entanglement entropy at (quantum) criticality

Cosmic strings are topological defects arising in a variety of cosmological scenarios, as the Universe undergoes symmetry-breaking phase transitions, whose discovery would offer valuable insight into the high-energy physics that shaped the early Universe. To interpret such a detection, robust theoretical models are essential. The velocity-dependent one-scale (VOS) model is particularly prominent: it self-consistently treats the network as a thermodynamic system, characterizing its key properties, and predicting its large-scale evolution. This has recently been extended to include superconducting cosmic strings, which carry additional degrees of freedom, giving rise to the charge-velocity dependent one-scale (CVOS) model. One limitation of the latter model is that it only included loss mechanisms for the charge and current. Here, we extend this model by phenomenologically including a possible energy source mechanism, specifically by allowing current-carrying strings interactions with an external magnetic field. We discuss how this coupling impacts the network’s evolution, present and classify the physically allowed scaling solutions for this extended CVOS model, and comment on the different impacts of the external magnetic field on the evolution of the network’s charge and current. Under our modeling assumptions, one of the ten physically plausible scaling solution enables the network to gain energy by this mechanism.

Portugal

P.B. Barbosa

C.J.A.P. Martins

Current-carrying string network evolution in an external magnetic field

We derive the Seiberg-Witten map to first order in the non-commutativity parameter for D-branes in the presence of a large R-R background field. This result enables a systematic investigation of the commutative formulation of the corresponding Lagrangian. In the SU( <italic>N</italic>) sector, the map introduces a non-local operator. In contrast, in the U(1) sector, this non-locality can be removed. This contrast suggests that the essential source of non-local behavior lies in the non-Abelian degrees of freedom. The commutative description obtained here offers further insight into both the Dirac-Born-Infeld structure and its possible extensions to the dynamics of M5-branes.

Chen-Te Ma

Relation between commutative and non-commutative descriptions of D-branes in large R-R field background

We study an analog information paradox in acoustic black holes which emerge from the superfluid surrounding a Schwarzschild black hole. The resulting acoustic black hole contains both acoustic horizons and optical horizons, with analog Hawking radiation, i.e., phonons, emitted from the outer acoustic horizon. By using the island formula, we calculate the entanglement entropy of analog Hawking radiation of the acoustic black hole in both nonextremal and extremal cases. In the nonextremal case, the entanglement entropy of phonons follows the Page curve due to the emergence of islands, and it is approximately proportional to the area of the acoustic horizon at late times. In the extremal case, the entanglement entropy of phonons diverges, leading to an ill-defined Page time. Our study verifies the unitarity of the analog gravity system and provides further insight into the connection between the entanglement entropy and the causal structure of spacetime.

Yu-Ye Cheng

Jia-Rui Sun

Island of an acoustic black hole in Schwarzschild spacetime

In this work, we investigate exact black string solutions in the context of $\textit{f}$($\textit{R}$, $\textit{T}$) gravity. Adopting the specific form $$f(R,T) = R + 2\chi T$$ , we consider an anisotropic Kiselev fluid as the matter content and obtain static cylindrical solutions, which are then extended to the rotating case through a suitable coordinate transformation. The influence of the quintessence state parameter $$w_q$$ and the matter–geometry coupling constant $$\chi $$ on the geometry is analyzed. We examine the weak, null, and strong energy conditions, identifying the regions in the parameter space where they are satisfied. Furthermore, we apply the Hamilton–Jacobi method to study the tunneling of scalar particles across the event horizon and derive the corresponding Hawking temperature. The thermodynamic stability of the solutions is investigated by computing the heat capacity, and the conditions for phase transitions are discussed. The results provide a characterization of black strings in $\textit{f}$($\textit{R}$, $\textit{T}$) gravity surrounded by quintessence, highlighting the combined effects of anisotropic matter and modified gravity on their physical properties.

Brazil

L. Santos

L. Barbosa

C. Barros

Kiselev black strings in $\textit{f}$($\textit{R}$, $\textit{T}$) gravity

We introduce and study a new solution describing a static, spherically symmetric and electrically charged black hole embedded in a charged quintessence fluid, which corresponds to an electric generalization of the Kiselev geometry. We derive the effective potential and analyze the various types of orbits followed by charged particles. A special attention is given to circular orbits and their stability. We found that for uncharged particles the periapsis shifts for bounded orbits is always prograde. However, for charged test particles the periapsis shifts can become retrograde in some cases.

Romania

Vitalie Lungu

Marina-Aura Dariescu

Cristian Stelea

Particle dynamics around an electrically charged Kiselev black hole embedded in quintessence

This research paper explores the structure of hypothetical compact stars, known as strange stars, within the framework of a novel modified theory of gravity called $$f(R,\Sigma ,T)$$ gravity. This theory extends General Relativity by making gravity dependent not only on the Ricci curvature scalar $\textit{R}$ but also on a torsion scalar $$\Sigma $$ and the trace of the matter energy–momentum tensor $\textit{T}$. This introduces a richer coupling between geometry and matter. The study presents a highly exotic, multi-layered stellar model composed of five distinct regions, each with a unique equation of state and geometric properties. The model features a dark-energy-like core with powerful repulsive gravity (anti-gravity), surrounded by successive layers of dust, exotic radiation, and a stiff matter crust, all enveloped by a standard Schwarzschild vacuum exterior. A key finding is the prevalence of negative energy densities and pressures in several layers, a hallmark of exotic matter. These configurations, enabled by the $$f(R,\Sigma ,T)$$ framework, lead to repulsive gravitational effects that radically alter the star’s internal equilibrium. The analysis demonstrates how additional geometry-driven forces within this theory can support such exotic structures, potentially preventing gravitational collapse and resulting in a stable, non-singular object. This work demonstrates that $$f(R,\Sigma ,T)$$ gravity allows for new and complex classes of compact objects with stratified, exotic matter distributions, whose properties and observational signatures would differ significantly from those predicted by standard General Relativity.

Egypt

M. Bakry

Saudi Arabia

A. Eid

Tahia Dabash

The impact of $$f(R,\Sigma ,T)$$ gravity on strange star structure

In this study, we analyze $\textit{f}$($\textit{R}$) gravity employing the $$ f(R) = R+ \alpha _1 R^p - \alpha _2 R^{-q} $$ model within the Friedmann–Lemaître–Robertson–Walker (FLRW) background. We derive the Friedmann equations via modified gravity action and subsequently reexpress them in terms of the standard Friedmann equations. Our investigation explores the behavior of a bouncing cosmological model within this modified gravity context, offering a potential solution to the singularity problem encountered in the standard Big Bang cosmology. We represent cosmological parameters as functions of cosmic time and scrutinize the conditions for a cosmic bounce. Additionally, we reconstruct the $\textit{f}$($\textit{R}$) gravity model using the redshift parameter and graphically present cosmological parameters as functions of redshift. These plots reveal an accelerated nature of Universe expansion. Furthermore, we reconstruct $\textit{f}$($\textit{R}$) gravity models for scale factors, $$a(t) = e^{e^{\lambda t}}$$ which exhibits the bouncing behavior. Finally, we investigated the stability scenario by examining the sound speed. The resulting graph of sound speed plotted against redshift confirms late-time stability.

Pakistan

M. Ilyas

Khalid Masood

Nehad Shah

Dynamical analysis of bouncing cosmology in the Capozziello–De Laurentis model of $\textit{f}$($\textit{R}$) gravity