In this article, we explore an anisotropic model to describe the Buchdahl compact star with a spherically symmetric matter distribution within the framework of modified <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>R</mi><mo stretchy='false'>)</mo></math> gravity. To achieve this, we consider the Starobinsky model <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>R</mi><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mi>R</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>&#945;</mi><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math>, where <italic>&#945;</italic> is a model parameter. To solve the Einstein Field equations, we adopt the embedded class-I geometry that satisfies the Karmarkar condition. Our analysis includes the generalized Darmois-Israel junction conditions, which are crucial for seamlessly matching the star's interior to the Schwarzschild exterior metric at the boundary in <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>R</mi><mo stretchy='false'>)</mo></math> gravity. These conditions have been employed to calculate the constant parameters by analyzing observational data from multiple compact stars, including <italic>Cen X-3, PSR J1903+327, Vela X-1</italic>, and <italic>PSR J1614-2230</italic>. This novel approach enables us to conduct a detailed analysis of Buchdahl compact star models and assess their physical viability. We also perform various physical tests, including equilibrium conditions and stability to evaluate the models' validity. The analysis of mass and radius reveals that the <math altimg='si3.svg'><mi>M</mi><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>R</mi></math> relationship is based on the Buchdahl limit and is sensitive to variations in the parameter <italic>&#945;</italic>. With <math altimg='si4.svg'><mi>&#945;</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>0</mn></math> representing General Relativity, the maximum mass and radius for different <italic>&#945;</italic> values were calculated and compared with observational data from the five aforementioned neutron stars. The range of maximum mass and radii are: <math altimg='si5.svg'><mo stretchy='false'>[</mo><mn>2.51</mn><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>2.54</mn><mspace width='0.25em' /><msub><mrow><mi>M</mi></mrow><mrow><mo>&#8857;</mo></mrow></msub><mo stretchy='false'>]</mo></math> and <math altimg='si6.svg'><mn>8.71</mn><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mn>9.33</mn><mspace width='0.25em' /><mtext>km</mtext></math>. The obtained values of radii align well with observed neutron star radii in X-ray binaries from spectroscopic studies, confirming the validity of the model.

India

Rajesh Kumar

Azerbaijan

Oman

S.K. Maurya

Y. Sekhmani

Saudi Arabia

Akram Ali

Uzbekistan

Farruh Atamurotov

Anisotropic compact stars in quadratic <italic>f</italic>( <italic>R</italic>) gravity and influence of quadratic parameter on properties of compact stars

Based on a previously derived superstring model possessing a cosmological sector that mimics Starobinsky inflation, we analyze several questions addressed in the recent literature: the generation of an effective $\textit{R}$ -term, the stability of the sgoldstino, the modular symmetry of the inflaton potential and the large distance swampland conjecture. We first show that the presence of the string dilaton stabilizes the sgoldstino direction in the supersymmetric case and no modification of the Kähler potential is needed. This is a generic property of a large class of Starobinsky type models within the framework of no-scale supergravity. We then present an explicit example of a string derived inflaton potential where the large values of the inflaton field during inflation imply a decompactification of two extra dimensions, while the scale of inflation is generated by higher order $\textit{α}$ -corrections via expectation values that cancel the D-term of an anomalous U(1) symmetry and break the modular symmetry of the scalar potential. As a result, the scale of inflation is much lower than the compactification scale which at the end of inflation is fixed at the free-fermionic self-dual point at an (approximate) supersymmetric minimum.

France

Thailand

Ignatios Antoniadis

Greece

United States

Switzerland

Dimitri Nanopoulos

Keith Olive

The 3 <italic>&#945;</italic> reaction plays a crucial role in stellar nucleosynthesis, as it is responsible for synthesizing carbon from helium. This reaction overcomes the <math altimg='si1.svg'><mi>A</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>5</mn></math> and <math altimg='si2.svg'><mi>A</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>8</mn></math> mass gaps, allowing the synthesis of heavier elements in stars. Additionally, this reaction significantly influences the evolution of the first-generation stars, accreting white dwarfs, and neutron stars. The relevant temperature range spans from 0.01 to 10 GK. Prior rate evaluations of the sequential process [ <italic>&#945;</italic>+ <italic>&#945;</italic>&#8594; 8Be( <italic>&#945;</italic>, <italic>&#947;</italic>) 12C] have primarily focused on the uncertainties associated with the resonance parameters in 8Be and 12C states. Since direct measurement data for the 8Be( <italic>&#945;</italic>, <italic>&#947;</italic>) 12C capture reaction is unavailable, the effect of interference between the direct (non-resonant) and resonance capture components of the 8Be( <italic>&#945;</italic>, <italic>&#947;</italic>) 12C capture reaction remains uncertain in the sequential 3 <italic>&#945;</italic> path. In particular, previous studies have not taken into account the uncertainty arising from this interference effect. In this work, a phenomenological <italic>R</italic>-matrix model has been employed to analyze the required <italic>&#945;</italic>+ <italic>&#945;</italic> scattering and the 8Be( <italic>&#945;</italic>, <italic>&#947;</italic>) 12C capture excitation functions. The present rate evaluation method incorporates uncertainties from both interference effects and resonance/bound-state parameters, utilizing updated nuclear data on 12C. The revised 3 <italic>&#945;</italic> reaction rate exhibits significantly greater uncertainty than previous evaluations due to the inclusion of interference effects in the 8Be( <italic>&#945;</italic>, <italic>&#947;</italic>) 12C reaction. Interference effects contribute approximately 75% to the total uncertainty. When considering only parameter uncertainties, the present rate aligns well with previous studies within the 0.1&#8211;2 GK temperature range. The present upper limits of the 3 <italic>&#945;</italic> rate are two orders of magnitude lower than the astrophysical limits.

Rajkumar Santra

Sk Mustak Ali

New limits on the 3 <italic>&#945;</italic> reaction rate from <italic>R</italic>-matrix modeling

We search for the leptonic decay $ D^+\to e^+\nu_{e} $ using an $ e^+e^- $ collision data sample with an integrated luminosity of 20.3 fb $ ^{-1} $ collected with the BESIII detector at a center-of-mass energy of 3.773 GeV. Significant signal is not observed, and an upper limit on the branching fraction of $ D^+\to e^+\nu_{e} $ is set as $ 9.7 \times 10^{-7} $ , at a confidence level of 90%. Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

O. Bakina

I. Balossino

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

R.A. Briere

A. Brueggemann

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.Y. Chen

S.K. Choi

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

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y. 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

Y.W. Fu

H. Gao

Search for the leptonic decay ${\boldsymbol D^{\bf +}{\bf\to}{\boldsymbol e}^{\bf +}\boldsymbol\nu_{\boldsymbol e}}$ * Supported in part by the National Key R&D Program of China (2023YFA1606000, 2020YFA0406400, 2020YFA0406300), the National Natural Science Foundation of China(NSFC) (11635010, 11735014, 11935015, 11935016, 11875054, 11935018, 12025502, 12035009, 12035013, 12061131003, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265, 12221005, 12225509, 12235017, 12361141819), the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program, the CAS Center for Excellence in Particle Physics (CCEPP), the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U2032104, U1832207), the 100 Talents Program of CAS, the Excellent Youth Foundation of Henan Scientific Commitee (242300421044), the Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology, the German Research Foundation DFG (FOR5327), the Istituto Nazionale di Fisica Nucleare, Italy, the Knut and Alice Wallenberg Foundation (2021.0174, 2021.0299), the Ministry of Development of Turkey (DPT2006K-120470), the National Research Foundation of Korea (NRF-2022R1A2C1092335), the National Science and Technology Fund of Mongolia, the National Science Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources & Institutional Development, Research, and Innovation of Thailand (B16F640076, B50G670107), the Polish National Science Center (2019/35/O/ST2/02907), the Swedish Research Council (2019.04595), the Swedish Foundation for International Cooperation in Research and Higher Education (CH2018-7756), and the US Department of Energy (DE-FG02-05ER41374).

The roles of the $ \Delta (1232) $ , $ {N}^{*}(1520) $ , and $ {N}^{*}(1650) $ resonances in the $ \gamma p\to{\pi }^{0}{\pi }^{0}p $ reaction near threshold is investigated within an effective Lagrangian approach. The differential cross sections of the $ \gamma p\to{\pi }^{0}{\pi }^{0}p $ reaction was calculated including contributions from the $ \Delta (1232) $ , $ {N}^{*}(1520) $ , and $ {N}^{*}(1650) $ intermediate states decaying into $ \pi^0 p $ via the $\textit{s}$-channel nucleon pole and $\textit{t}$-channel $\textit{ρ}$ exchange. Current experimental measurements were well reproduced. The production of $ \Delta(1232) $ was mainly from the mechanism of the $\textit{s}$-channel nucleon pole, while the $ {N}^{*}(1520) $ and $ {N}^{*}(1650) $ were produced from the mechanism of the $\textit{t}$-channel $\textit{ρ}$ exchange. More experimental data on the $ \gamma p \to \pi^0 \pi^0 p $ reaction could be used to explore the properties of the low-lying excited baryon state.

Meng-Yuan Dai

Si-Wei Liu

Cheng Chen

De-Min Li

En Wang

Ju-Jun Xie

Roles of ${\boldsymbol\Delta(\bf 1232)}$ , ${\boldsymbol N^*(\bf 1520)}$ , and ${\boldsymbol N^*(\bf 1650)}$ resonances in ${\boldsymbol\gamma \boldsymbol p\to \boldsymbol\pi^{\bf 0} \boldsymbol\pi^{\bf 0}\boldsymbol p}$ reaction within an effective Lagrangian approach * Supported by the National Key R&D Program of China (2023YFA1606703, 2024YFE0105200), the Natural Science Foundation of Henan Province, China (232300421140, 222300420554), and the National Natural Science Foundation of China (12435007, 12361141819, 12475086, 12192263)

We study the nonleptonic puzzle of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mrow><mi>d</mi><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> decay in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math>-parity violating minimal supersymmetric standard model extended with the inverse seesaw mechanism. In this model, the chiral flip of sneutrinos can contribute to the observables <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mrow><mi>K</mi><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover></mrow></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mrow><msup><mi>K</mi><mo>*</mo></msup><msup><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup></mrow></msub></math>, that is beneficial for explaining the relevant puzzle. We also find that this unique effect can engage in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub><mtext>−</mtext><msub><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></msub></math> mixing. We utilize the scenario of complex <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mo>′</mo></msup></math> couplings to fulfill the recent stringent constraint of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub><mtext>−</mtext><msub><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></msub></math> mixing, and examine other related bounds of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>K</mi></mrow></math>-meson decays, lepton decays, neutrino data, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> decays, oblique parameters, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violations, etc. Besides, inspired by the new measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><mi>ν</mi><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo></math> by Belle II, which shows about <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2.7</mn><mi>σ</mi></math> higher than the Standard Model prediction, we also investigate the New Physics enhancement to this observable.

Min-Di Zheng

Qi-Liang Wang

Li-Fen Lai

Hong-Hao Zhang

Explaining the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mrow><mi>d</mi><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> puzzle via a chiral flip in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math>-parity violating MSSM with the seesaw mechanism

The study of modified gravity models has garnered significant attention because of their potential to provide alternative explanations for cosmological phenomena, such as the accelerated expansion of the universe and the nature of dark energy. One such model, the Einstein–Gauss–Bonnet–Myrzakulov <math altimg='si1.svg'><mi>R</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>F</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mi>G</mi><mo stretchy='false'>)</mo></math> gravity (EGBMG), which incorporates the curvature <italic>R</italic>, torsion <italic>T</italic>, and the Gauss-Bonnet term <italic>G</italic>, offers a promising framework to explore the dynamics of the universe and its evolution. This paper delves into the theoretical and observational implications of the EGBMG model, focusing on its ability to address long-standing challenges in cosmology, including the evolution of dark energy and the transition from early-time inflationary behavior to late-time acceleration. We review recent advancements in the model, including its compatibility with observational data and its ability to provide new insights into cosmic acceleration. Through a combination of theoretical models, dynamical systems analysis, and cosmological diagnostics, we demonstrate the robustness of the EGBMG framework in explaining the large-scale structure of the universe and its accelerated expansion. This paper serves as a step toward further exploring the potential of this model to understand the fundamental forces driving the cosmos and its consistency with modern observational constraints in Weitzenb&#246;ck spacetime.

South Africa

Davood Momeni

Kazakhstan

Ratbay Myrzakulov

Einstein–Gauss–Bonnet–Myrzakulov gravity from <italic>R</italic>&#8239;+&#8239; <italic>F</italic>( <italic>T</italic>, <italic>G</italic>): Numerical insights and torsion&#8211;Gauss&#8211;Bonnet dynamics in Weitzenb&#246;ck spacetime

This study investigates the asymptotic symmetry algebras (ASA) of Jackiw–Teitelboim (JT) gravity within the framework of $$\mathfrak {sl}(3,\mathbb {R})$$ symmetry. By explicitly constructing this algebra, we explore how the presence of the dilaton field influences the structure of asymptotic symmetries and symmetry breaking mechanisms at the AdS $$_2$$ boundary. For the $$\mathfrak {sl}(3,\mathbb {R})$$ model, the dilaton field preserves a subset of the complete $$W_3$$ -symmetry, restricting the algebra to $$\mathfrak {sl}(3,\mathbb {R})$$ . These results provide deeper insights into the role of dilaton dynamics in holographic dualities, with implications for the thermodynamics and geometry of AdS $$_2$$ . The findings pave the way for systematically exploring extended gauge symmetries in two-dimensional gravity and their relevance to higher-rank Lie algebras.

H. Özer

Aytül Filiz

On the explicit asymptotic symmetry breaking of $$sl(3,\mathbb {R})$$ Jackiw–Teitelboim gravity

We study the 1D Ising model with long-range interactions decaying as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><msup><mi>r</mi><mrow><mn>1</mn><mo>+</mo><mi>s</mi></mrow></msup></math>. The critical model corresponds to a family of 1D conformal field theories whose data depend nontrivially on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> in the range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mn>2</mn><mo>≤</mo><mi>s</mi><mo>≤</mo><mn>1</mn></math>. The model is known to be described by a generalized free field with quartic interaction, which is weakly coupled near <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>=</mo><mn>1</mn><mo>/</mo><mn>2</mn></math> but strongly coupled near the short-range crossover at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>=</mo><mn>1</mn></math>. We propose a dual description that becomes weakly coupled at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>=</mo><mn>1</mn></math>. At <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>=</mo><mn>1</mn></math>, our model becomes an exactly solvable conformal boundary condition for the 2D free scalar. We perform a number of consistency checks of our proposal and calculate the perturbative conformal field theory data around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>=</mo><mn>1</mn></math> analytically using both (1) our proposed field theory and (2) the analytic conformal bootstrap. Our results show complete agreement between the two methods.

Dario Benedetti

Edoardo Lauria

Dalimil Mazáč

Philine van Vliet

One-Dimensional Ising Model with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><msup><mi>r</mi><mn>1.99</mn></msup></math> Interaction

This study explores the thermodynamic properties of evolving Lorentzian wormholes within the framework of <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi mathvariant='script'>R</mi><mo>,</mo><mi mathvariant='script'>T</mi><mo stretchy='false'>)</mo></math> gravity. This modified gravity theory extends general relativity by incorporating the Ricci scalar ( <math altimg='si2.svg'><mi mathvariant='script'>R</mi></math>) and the trace of the energy-momentum tensor ( <math altimg='si3.svg'><mi mathvariant='script'>T</mi></math>). We investigate the thermodynamics of wormholes at their dynamic apparent horizon, deriving expressions for the entropy variation and testing the validity of the generalized second law of thermodynamics (GSL). Employing both the first law of thermodynamics and the area law formalism, which relates entropy to the horizon area, we explore the evolution of entropy and confirm the consistency of thermodynamic principles within this framework. Furthermore, we examine key physical properties such as stability conditions, active gravitational mass, and total gravitational energy. Our findings provide deeper knowledge into wormhole thermodynamics and wormhole physics, particularly within modified gravity models, and contribute to the broader understanding of the thermodynamic behavior of evolving wormhole spacetimes.

C.S. Varsha

L. Sudharani

N.S. Kavya

V. Venkatesha

Thermodynamic insights into evolving Lorentzian wormholes in <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi mathvariant='script'>R</mi><mo>,</mo><mi mathvariant='script'>T</mi><mo stretchy='false'>)</mo></math> gravity