The magnitude of the direct CP asymmetry generated during the weak decay of hadrons is attributed to the weak phase and certain strong phases. The weak phase originates from the CKM matrix, while a strong phase may result from the resonance effect produced by the mixing of vector mesons $ V\left\{\rho^{0}(770),\,\omega(782),\,\phi(1020)\right\} $ to $ \pi^+ \pi^- $ meson pairs. $ \rho^{0}(770) $ can decay directly into $ \pi^+ \pi^- $ meson pairs; both $ \omega(782) $ and $ \phi(1020) $ can also decay into $ \pi^+ \pi^- $ meson pairs, with a small contribution from isospin symmetry breaking. The main contribution for the middle state vector meson $ \rho^{0}(770)-\omega(782)-\phi(1020) $ interference is the mix of $ \rho^{0}(770) $ , $ \omega(782)-\rho^{0}(770) $ , and $ \phi(1020)-\rho^{0}(770) $ . We calculated the CP asymmetry and decay branching ratio for $ \bar{B}^0_{s} \rightarrow \pi^+ \pi^- \pi^0 (\bar K ^{0}) $ within the framework of QCD factorization and compared them with previous studies. We also analyzed the $ \bar{B}^0_{s} \rightarrow \pi^+ \pi^- \eta(\eta^{(')}) $ decay process. The results show that the CP asymmetry of these four decay processes is significantly enhanced, especially for the $ \bar{B}^0_{s} \rightarrow \pi^+ \pi^- \bar K ^{0} $ decay process. Moreover, the decay branching ratio also changes under the resonance effect. These results might provide support for the experimental analysis of the $ \bar B^{0}_s $ meson.

China

Xi-Liang Yuan

Chao Wang

Zhuang-Dong Bai

Gang Lü

Role and contribution of the resonance effect for the decay process of ${ \bar {\boldsymbol B}^{\bf 0}_{\boldsymbol s} \boldsymbol\rightarrow \boldsymbol\pi^{+}\boldsymbol\pi^{-}{\boldsymbol P}}$ * Supported by National Natural Science Foundation of China (Project No.11805153) and Natural Science Foundation of Henan Province (Project No.252300420319)

In this article, we develop two unique singularity-free solutions that describe anisotropic interior fluid configurations in <math altimg='si6.svg'><mrow><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></math> gravity. In this regard, the extended field equations are developed corresponding to a static interior spacetime. This system of equations is facilitated by imposing two novel constraints in order to get a unique solution. We derive two different solutions by choosing specific types of anisotropic pressure. While solving these equations, several constants are involved as a result of performing exact integration. Matching the interior metric to the Schwarzschild exterior metric at the sphere&#8217;s boundary in both scenarios yields these integration constants. Another factor that plays an important role in finding the constants is the zero radial pressure. Afterwards, physical feasibility of both compact models is explored under specific conditions. To do so, the predicted data of two stars, named 4U 1820-30 and Cen X-3 is used along with different values of the model parameter. It is reported that both our astrophysical solutions are aligned with the criteria of physical existence of such models under certain parametric values.

Pakistan

Azerbaijan

Tayyab Naseer

M. Sharif

M. Waqas

Saudi Arabia

Mohamed R. Eid

Abdel-Haleem Abdel-Aty

Astrophysical stellar models in <math altimg='si6.svg'><mrow><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></math> gravity under Tolman IV and Kohler-Chao-Tikekar spacetimes

The radiative leptonic $$B \rightarrow \gamma \ell \nu _{\ell }$$ decay serves as an ideal platform to determine the $\textit{B}$-meson inverse moment which is a fundamental nonperturbative parameter for the $\textit{B}$ meson. In this paper, we explore precise QCD contributions to this decay with an energetic photon. We reproduce the next-to-next-to-leading-logarithmic resummation formula for the decay amplitude at leading power in $$\Lambda _\textrm{QCD}/m_b$$ . Employing operator identities, we calculate subleading-power contributions from the expansion of the hard-collinear propagator of the internal up quark and the heavy-quark expansion of the bottom quark. We update the contributions from the hadronic structure of the photon to the $$B \rightarrow \gamma \ell \nu _{\ell }$$ process with the dispersion technique. Together with other yet known power corrections, phenomenological applications including the partial branching fraction and ratio of the branching fractions of the radiative $\textit{B}$ decay are investigated.

Bo-Yan Cui

Yue-Long Shen

Germany

Yan-Bing Wei

QCD factorization for the $$B \rightarrow \gamma \ell \nu _{\ell }$$ decay beyond leading power

We study $ \cos2\phi $ azimuthal asymmetry in doubly longitudinally polarized proton-proton Drell-Yan collisions within the transverse momentum dependent factorization framework. The asymmetry arises from the convolution of the longitudinal transversity distribution $ h_{1L}^{\perp} $ for both protons. Using the Bacchetta-Delcarro-Pisano-Radici-Signori parameterization for the nonperturbative Sudakov form factor and the Wandzura-Wilczek approximation for collinear $ h_{1L}^{\perp} $ , we predict the double spin asymmetry $ A_{LL}^{\cos2\phi} $ at RHIC and NICA kinematics. Our results demonstrate sensitivity to sea quark distributions, with the asymmetry reaching up to 25% for maximal sea quark contributions. These predictions highlight the potential of polarized Drell-Yan measurements to probe sea quark dynamics and advance our understanding of nucleon structures.

Hui Li

Ting Hu

Liang-Liang Liu

Xiao-Yu Wang

Zhun Lu

Asymmetry ${{\boldsymbol A}_{\boldsymbol{LL}}^{\bf\cos2\boldsymbol\phi}} $ in the polarized proton-proton Drell-Yan process within TMD factorization * Hui Li is supported by Fundamental Research Program of Shanxi Province (202203021222224) and Natural Science Foundation of Shanxi Normal University (JCYJ2023021). Xiao-Yu Wang is supported by the Natural Science Foundation of Henan Province (242300421377, 232300421140)

We propose a search strategy at the HL-LHC for a new neutral particle $\textit{X}$ that couples to $\textit{W}$-bosons, using the process $ p p \to W^{\pm} X (\to W^{+} W^{-}) $ with a tri-$\textit{W}$-boson final state. Focusing on events with two same-sign leptonic $\textit{W}$-boson decays into muons and a hadronically decaying $\textit{W}$-boson, our method leverages the enhanced signal-to-background discrimination achieved through a machine-learning-based multivariate analysis. Using the heavy photophobic axion-like particle (ALP) as a benchmark, we evaluate the discovery sensitivities on both production cross section times branching ratio $ \sigma(p p \to W^{\pm} X) \times \text{Br}(X \to W^{+} W^{-}) $ and the coupling $ g_{aWW} $ for particle mass over a wide range of 170–3000 GeV at the HL-LHC with center-of-mass energy $ \sqrt{s} = 14 \, \text{ TeV} $ and integrated luminosity $ {\cal{L}} = 3 \, \text{ab}^{-1} $ . Our results show significant improvements in discovery sensitivity, particularly for masses above 300 GeV, compared to existing limits derived from CMS analyses of Standard Model (SM) tri-$\textit{W}$-boson production at $ \sqrt{s} = 13 \, \text{ TeV} $ . This study demonstrates the potential of advanced selection techniques in probing the coupling of new particles to $\textit{W}$-bosons and highlights the HL-LHC's capability to explore physics beyond the SM.

Ying-nan Mao

Kechen Wang

Yiheng Xiong

Sensitivities of new resonance couplings to $\textit{W}$-bosons at the LHC * Ying-nan Mao and Yihen Xiong are supported by the National Natural Science Foundation of China (12205227). Kechen Wang is supported by the National Natural Science Foundation of China (11905162), the Excellent Young Talents Program of the Wuhan University of Technology (40122102), and the research program of the Wuhan University of Technology (2020IB024). The simulation and analysis work of this article was completed with the computational cluster provided by the Theoretical Physics Group at the Department of Physics, School of Physics and Mechanics, Wuhan University of Technology

The production of heavy-quark (HQ) jets is a new area that addresses the mass effect of jet quenching in heavy-ion physics. This paper presents a theoretical study of HQ jet yield suppression in Pb+Pb collisions at the Large Hadron Collider (LHC) and focuses on the energy loss of HQ jets produced by different mechanisms. The $\textit{p+p}$ baseline is provided by the generator simulation of high-energy reactions of particles (SHERPA), and the jet-medium interactions are described by the SHELL transport model, which considers the elastic and inelastic partonic energy loss in the quark-gluon plasma (QGP). In $\textit{p+p}$ collisions, our numerical results indicate that the HQ jets from gluon splitting ( $ g \rightarrow Q $ -jet) are the dominant contribution at high $ p_T $ , displaying more dispersive structures than the HQ-initiated ( $ Q \rightarrow Q $ -jet). In nucleus-nucleus collisions, our calculations were consistent with the inclusive and b-jet $ R_{AA} $ recently measured by the ATLAS collaboration, revealing a remarkable manifestation of the mass effect of jet energy loss. As a result of the dispersive substructure, the $ g \rightarrow Q $ -jet loses more energy than the $ Q \rightarrow Q $ -jet in the QGP. Due to the significant contribution of $ g \rightarrow c $ -jet, the $ R_{AA} $ of $\textit{c}$-jet is comparable or even smaller than that of inclusive jet. To experimentally distinguish the $ g \rightarrow Q $ -jet and $ Q \rightarrow Q $ -jet, we propose event selection strategies based on their topological features and test their performances. By isolating the $ c \rightarrow c $ -jet, $ b \rightarrow b $ -jet, and the jets initiated by heavy quarks, we predicted that the order of their $ R_{AA} $ are in line with the mass hierarchy of energy loss. Future measurements on the $ R_{AA} $ of $ Q \rightarrow Q $ -jet and $ g \rightarrow Q $ -jet will provide a unique opportunity for testing the flavor/mass dependence of energy loss at the jet level.

Sa Wang

Shuang Li

Yao Li

Ben-Wei Zhang

Enke Wang

Probing the mass effect of heavy quark jets in high-energy nuclear collisions * Supported by the MajorProject of Basic and Applied Basic Research of Guangdong Province, China (2020B0301030008, 2023A1515011460), and the National Natural Science Foundation of China (11935007, 12035007, 12247127, 12375137). Sa Wang is supported by the Open Foundation of Key Laboratory of Quark and Lepton Physics (MOE) (QLPL2023P01) and the Talent Scientific Star-up Foundation of the China Three Gorges University, China (CTGU) (2024RCKJ013)

We calculate the time-like $$\rho $$ electromagnetic (EM) form factor in the $$k_T$$ factorization formalism by including the next-to-leading-order (NLO) corrections of the leading-twist and sub-leading twist contributions. It’s observed that the NLO correction to the magnitude of the LO leading-twist form factor is lower than $$30\%$$ at large invariant mass squared $$Q^2 > 30 \,\text {GeV}^2$$ . It is found that the $$\rho $$ meson EM form factor is dominated by twist-3 contribution instead of by twist-2 one because of the end-point enhancement. The theoretical predictions of the moduli of three helicity amplitudes and total cross section are analyzed at $$\sqrt{s}=10.58$$ GeV, which are consistent with measurements from BABAR Collaboration.

Ya-Lan Zhang

Si-Yu Wang

Zhen-Jun Xiao

Ya Li

Next-to-leading-order time-like rho electromagnetic form factors in $${k_{\textrm{T}}}$$ factorization

<p>We accomplish for the first time the next-to-leading-order computation of the weak annihilation contribution to the electroweak penguin decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mrow><mo stretchy="false">{</mo><mi>K</mi><mo>,</mo><mi>π</mi><mo stretchy="false">}</mo></mrow><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math>, which is an essential missing piece of the complete QCD correction to the matrix elements of hadronic operators in the weak effective Hamiltonian. Both the hard functions and the jet functions in the perturbative factorization formulas from the short-distance fluctuations at the two distinct scales <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>b</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mrow><msub><mi>m</mi><mi>b</mi></msub><mi mathvariant="normal">Λ</mi></mrow></msqrt></math> are determined at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">)</mo></math>. We then demonstrate that the one-loop weak annihilation correction can bring about the noticeable impacts on theory predictions for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetries and the isospin asymmetry in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>π</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> decays.</p>

Yong-Kang Huang

Yu-Ming Wang

Next-to-Leading-Order Weak-Annihilation Correction to Rare <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi><mo stretchy="false">→</mo><mo stretchy="false">{</mo><mi>K</mi><mo>,</mo><mi>π</mi><mo stretchy="false">}</mo><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> Decays

The direct CP asymmetry in the weak decay process of hadrons is commonly attributed to the weak phase of the CKM matrix and the indeterminate strong phase. We propose a method to generate a significant phase difference through the interference between ρ and ω mesons, taking into account the G-parity allowed decay process of   $\omega \rightarrow \pi^{+}\pi^{-}\pi^{0}$   and the G-parity-suppressed decay process of   $\omega \rightarrow \pi^{+}\pi^{-}\pi^{0}$   in B meson decays. This interference can lead to notable changes in the CP asymmetry within the interference region. Additionally, we calculate the integral results for different phase space regions of the four-body decay process. We hope that our work provides valuable theoretical guidance for future experimental investigations on CP asymmetry in these decays.

Na Wang

The resonance effect for the CP asymmetry associated with the process   

We construct a new stellar compact object model in the regime of anisotropic pressure using the framework of gravitational decoupling via minimal geometric deformation, with the particularity that the seed solution used is the known Kohler–Chao–Tikekar cosmological solution. As an extra condition to close the Einstein’s field equations resulting for this construction, we use a generalised complexity factor for self-gravitating spheres to the well-known Wyman IIa solution. The resulting model fulfils the fundamental physical acceptability stellar conditions for a compactness factor of a pulsar SMC X-1. The stability of the model is also investigated.

Ecuador

B. Siza

J. Andrade

D. Santana

Anisotropic extension of the Kohler–Chao–Tikekar cosmological solution with like Wyman IIa complexity factor