Polarization is a prominent feature of gravitational wave observations and can be used to distinguish between different modified gravity theories. Compared to General Relativity, $\textit{f}$($\textit{R}$) gravity exhibits an additional polarization originating from a scalar field, which is a combination of the longitudinal and breathing modes. When the scalar mass of $\textit{f}$($\textit{R}$) is zero, the mixed mode will reduce to a pure breathing mode with the disappearance of the longitudinal mode. However, this reducing seems to be disallowed because a positive scalar mass is often required to maintain the stability of the cosmological perturbation. In fact, the massless scalar case can provide a stable perturbation, but more detailed constraints need to be considered. For the completeness of the polarization analysis, we explore the possibility that there are stable massless scalar polarizations in viable dark energy $\textit{f}$($\textit{R}$) models. We find that the existence of stable massless scalar polarization depends on the structure of $\textit{f}$($\textit{R}$) model and can be used to distinguish different models in $\textit{f}$($\textit{R}$) gravity.

China

Xin-Dong Du

Peng-Cheng Li

Stable massless scalar polarization of $\textit{f}$($\textit{R}$) gravity

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

An investigation of high-transverse-momentum (high-<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>) photon-triggered jets in proton-proton (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mtext>−</mtext><mi>p</mi></mrow></math>) and ion-ion (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>A</mi><mtext>−</mtext><mi>A</mi></mrow></math>) collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>0.2</mn></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>5.02</mn><mspace width="0.28em"></mspace><mi>TeV</mi></mrow></math> is carried out, using the multistage description of in-medium jet evolution. Monte Carlo simulations of hard scattering and energy loss in heavy-ion collisions are performed using parameters tuned in a previous study of the nuclear modification factor (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math>) for inclusive jets and high-<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math> hadrons. We obtain a good reproduction of the experimental data for photon-triggered jet <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math>, as measured by the ATLAS detector, the distribution of the ratio of jet to photon <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math> (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>X</mi><mrow><mi>J</mi><mi>γ</mi></mrow></msub></math>), measured by both CMS and ATLAS, and the photon-jet azimuthal correlation as measured by CMS. We obtain a moderate description of the photon-triggered jet <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>I</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math>, as measured by STAR. A noticeable improvement in the comparison is observed when one goes beyond prompt photons and includes bremsstrahlung and decay photons, revealing their significance in certain kinematic regions, particularly at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>X</mi><mrow><mi>J</mi><mi>γ</mi></mrow></msub><mo>&gt;</mo><mn>1</mn></mrow></math>. Moreover, azimuthal angle correlations demonstrate a notable impact of bremsstrahlung photons on the distribution, emphasizing their role in accurately describing experimental results. This work highlights the success of the multistage model of jet modification to straightforwardly predict (this set of) photon-triggered jet observables. This comparison, along with the role played by bremsstrahlung photons, has important consequences on the inclusion of such observables in a future Bayesian analysis.

C. Sirimanna

Japan

Y. Tachibana

A. Majumder

A. Angerami

R. Arora

S.A. Bass

Y. Chen

R. Datta

Canada

L. Du

R. Ehlers

Germany

H. Elfner

R.J. Fries

C. Gale

Y. He

B.V. Jacak

P.M. Jacobs

S. Jeon

Y. Ji

F. Jonas

L. Kasper

M. Kordell

A. Kumar

R. Kunnawalkam-Elayavalli

J. Latessa

Y.J. Lee

United Kingdom

R. Lemmon

Brazil

M. Luzum

S. Mak

A. Mankolli

C. Martin

H. Mehryar

T. Mengel

C. Nattrass

J. Norman

C. Parker

J.F. Paquet

J.H. Putschke

H. Roch

G. Roland

B. Schenke

L. Schwiebert

A. Sengupta

C. Shen

M. Singh

D. Soeder

R.A. Soltz

Finland

I. Soudi

J. Velkovska

G. Vujanovic

X.N. Wang

X. Wu

W. Zhao

Hard-photon-triggered jets in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mtext>−</mtext><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>A</mi><mtext>−</mtext><mi>A</mi></mrow></math> collisions

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.

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

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

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)