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.

China

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)

Focusing on the recent measurements of the scattering processes <math altimg='si1.svg'><mover accent='true'><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mi>p</mi><mo stretchy='false'>&#8594;</mo><mover accent='true'><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mi>p</mi></math> and <math altimg='si2.svg'><mi mathvariant='normal'>&#923;</mi><mi>p</mi><mo stretchy='false'>&#8594;</mo><mi mathvariant='normal'>&#923;</mi><mi>p</mi></math> reported by BESIII, we offer a dynamical interpretation of the differences in the measured total and differential cross sections for both processes. This discrepancy arises because the <italic>u</italic>-channel contribution is forbidden for <math altimg='si1.svg'><mover accent='true'><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mi>p</mi><mo stretchy='false'>&#8594;</mo><mover accent='true'><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mi>p</mi></math> but allowed for <math altimg='si2.svg'><mi mathvariant='normal'>&#923;</mi><mi>p</mi><mo stretchy='false'>&#8594;</mo><mi mathvariant='normal'>&#923;</mi><mi>p</mi></math>. Additionally, we examine the enhancement effect in the forward angle region of the differential cross section for <math altimg='si3.svg'><mover accent='true'><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mi>p</mi></math> elastic scattering, attributed to the <italic>t</italic>-channel contribution. This work serves as a test to the scattering mechanism involved in these reactions.

Xiao-Yun Wang

Yuan Gao

Xiang Liu

Understanding of the BESIII measurement of (anti)hyperon-nucleon scattering

<p>In this study, applying the effective Lagrangian approach, we investigate the reaction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>*</mo></mrow></msup><mi mathvariant="normal">Σ</mi></mrow></math> to explore the production of the hidden-strange molecular pentaquarks <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>s</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></mrow></msub></math>. Specifically, we analyze two scenarios, where the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup></math> quantum numbers of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>s</mi><mover accent="true"><mrow><mi>s</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></msub></mrow></math> are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>3</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math>. Our results show that the contribution from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>s</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></mrow></msub></math> exchange dominates the total cross section, surpassing those from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi></math>-channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> exchange and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>-channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Σ</mi></math> exchange. Additionally, we present predictions for the differential cross section of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>*</mo></mrow></msup><mi mathvariant="normal">Σ</mi></mrow></math> process. Finally, we extend the 2-to-2 scattering process to the 2-to-3 Dalitz process and provide theoretical predictions for this scenario. Our findings suggest that the cross section for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>*</mo></mrow></msup><mi mathvariant="normal">Σ</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi mathvariant="normal">Σ</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> process can reach several tens of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi><mi>b</mi></math> near the threshold, making it highly favorable for experimental measurement. However, the current scarcity of experimental data for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>*</mo></mrow></msup><mi mathvariant="normal">Σ</mi></mrow></math> reaction at threshold energy limits our ability to determine the properties of the hidden-strange molecular pentaquarks <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>s</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></mrow></msub></math> and related physical quantities. Therefore, additional experimental measurements of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mo>*</mo></msup><mi mathvariant="normal">Σ</mi></math> reaction at threshold are strongly encouraged, and correlation studies could be pursued at facilities such as J-PARC, AMBER, and upcoming HIKE and HIAF meson beam experiments.</p>

Production potential of hidden-strange molecular pentaquarks through the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo mathvariant="bold">*</mo></mrow></msup><mi mathvariant="normal">Σ</mi></mrow></math> process

We use an effective Lagrangian approach to investigate the production of the anticharmed pentaquark state $$P_{\bar{c}s}^{(*)-}$$ with the minimal quark content $$\bar{c}sudd$$ in the $$\Lambda _b^0$$ decay. In our calculation, the $$P_{\bar{c}s}^{(*)-}$$ is considered as the molecule state of the $$nD_{s0(s1)}^{-}$$ in an wave, and its production and decay occur via triangle loops at the hadron level. With the moderate model parameters, the computed results suggest that the branching fractions of $$\Lambda _b^0\rightarrow P_{\bar{c}s}^{(*)-} D^+ $$ can reach approximately $$10^{-4}$$ . The possible decay modes $$ P_{\bar{c}s}^{(*)-} \rightarrow \Lambda D^{(*)-}$$ and $$ P_{\bar{c}s}^{(*)-} \rightarrow \Sigma D^{(*)-}$$ are also investigated. It is hoped that these predictions could be helpful in searching for the anticharmed-strange pentaquark candidates in future LHCb experiments.

Shi-Dong Liu

Xiao-Hai Liu

Gang Li

Production and decay of anticharmed pentaquark state with quark content $$\bar{c}sudd$$

In this work, under the framework of the vector meson dominance model, the trace anomaly contribution value inside neutrons is extracted for the first time based on vector meson photoproduction data. Furthermore, we systematically compare and analyze the trace anomaly contributions of protons and neutrons. The results show that the trace anomaly contributions of protons and neutrons are close, which indirectly confirms that their internal structures and dynamic properties may have certain similarities. In addition, the main factors affecting the extraction of the trace anomaly contribution of nucleons are discussed in detail. This study not only provides a theoretical basis for us to better understand the source of nucleon mass but also makes a useful exploration and discussion on how to extract the trace anomaly contribution of nucleons more accurately in the future.

Jingxuan Bu

Systematic investigation of trace anomaly contribution in nucleon mass

In this work, the production of the hidden-strange pentaquarklike state, <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math>, via the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi></math> scattering process is studied by the effective Lagrangian approach. Concretely, we consider the <math><mi>ρ</mi></math> meson exchange of <math><mi>t</mi></math>-channel and the nucleon exchange of <math><mi>u</mi></math>-channel, which are treated as the background terms, and take into account the contribution of the <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math> via the <math><mi>s</mi></math>-channel as a signal term. By global fitting of the total and differential cross sections of the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>ϕ</mi><mi>n</mi></math> process, it is shown that the <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math> contributes an obvious peak at the threshold energy point of the differential cross section at the forward angle (<math><mi>cos</mi><mi>θ</mi><mo>=</mo><mn>1</mn></math>), which provides clues to the detection of the <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math> by the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi></math> scattering process. However, due to the limited accuracy of the experimental data, it is an objective limitation for us to determine the properties of the <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math> by the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi></math> scattering process. Therefore, more accurate experimental measurements of the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>ϕ</mi><mi>n</mi></math> reaction are highly desirable, and we have also proposed that correlation measurements can be performed on J-PARC, AMBER, and future HIKE and HIAF meson beam experiments.

Hui-Fang Zhou

Prospects for detecting the hidden-strange pentaquarklike state <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>2080</mn><mo>)</mo></math> in the <math><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>ϕ</mi><mi>n</mi></math> reaction

We systematically analyze the quark and gluon gravitational form factors (GFFs) of the proton by connecting the energy-momentum tensor and near-threshold vector meson photoproduction (NTVMP). Specifically, the quark contributions of GFFs are determined by applying global fitting to the cross section of the lightest vector meson   $ \rho^0 $   photoproduction. Combined with the gluon GFFs obtained from heavy quarkonium   $ \rho^0 $   photoproduction data, the complete GFFs are obtained and compared with the experimental results and lattice quantum chromodynamics determinations. In addition, we use the resonance via Padé (RVP) method based on the Schlessinger point method to obtain a model-independent quark D-term distribution through direct analytical continuation of deeply virtual Compton scattering experimental data. If errors are considered, the results obtained with RVP are essentially consistent with those obtained by NTVMP. Moreover, the comprehensive information on GFFs helps to uncover the mass distribution and mechanical properties inside the proton. This study is not only an important basis for delving into the enigmatic properties of the proton, but also has significance for theoretically guiding future JLab and EIC experimental measurements.

Fancong Zeng

Jiyuan Zhang

Gravitational form factors of the proton from near-threshold vector meson photoproduction  

Under the framework of the vector meson dominance model, the absolute scattering lengths of light vector mesons (<math><mi>ϕ</mi><mo>,</mo><mo> </mo><mi>ω</mi></math>, and <math><mi>ρ</mi></math>) with the deuteron are calculated from the cross sections of vector meson photoproduction off a deuteron. Additionally, a fitting function is used to predict the scattering lengths of the heavy vector mesons <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><mo>−</mo><mi>d</mi></math> and <math><mi>Υ</mi><mo>−</mo><mi>d</mi></math>. Based on these results, the distribution of the scattering lengths <math><mrow><mrow><mo>|</mo></mrow><msub><mi>α</mi><mrow><mi>V</mi><mi>d</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math> between vector mesons and the deuteron is presented and compared with the scattering lengths <math><mrow><mrow><mo>|</mo></mrow><msub><mi>α</mi><mrow><mi>V</mi><mi>p</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math> between vector mesons and the proton. It is found that as the mass of the vector meson increases, the scattering lengths <math><mrow><mrow><mo>|</mo></mrow><msub><mi>α</mi><mrow><mi>V</mi><mi>d</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math> become closer to <math><mrow><mrow><mo>|</mo></mrow><msub><mi>α</mi><mrow><mi>V</mi><mi>p</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math>. In addition, the correlation analysis indicates a strong positive relationship between the scattering length and the vector meson radius with a high correlation coefficient. The implications of results are essential for improving our understanding of the interaction between hadron and nucleus.

Chen Dong

Quanjin Wang

First characterization of the scattering length distribution of the vector meson interaction with the deuteron

In this work, we investigate the production of isovector scalar meson <math><msub><mi>a</mi><mn>0</mn></msub><mo>(</mo><mn>1817</mn><mo>)</mo></math> by the effective Lagrangian approach. Specifically, we employ the Reggeized <math><mi>t</mi></math> channel Born term to calculate the total and differential cross sections for the reaction <math><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msub><mi>a</mi><mn>0</mn></msub><mo>(</mo><mn>1817</mn><mo>)</mo><mi>Λ</mi></math>. Our analysis reveals that the optimal energy range for detecting the <math><msub><mi>a</mi><mn>0</mn></msub><mo>(</mo><mn>1817</mn><mo>)</mo></math> meson lies between <math><mi>W</mi><mo>=</mo><mn>3.4</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and <math><mi>W</mi><mo>=</mo><mn>3.6</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, where the predicted total cross section reaches a minimum value of 112 nb. Notably, the <math><mi>t</mi></math> channel, as predicted by the Regge model, significantly enhances the differential cross sections, particularly at extreme forward angles. Furthermore, we investigate the Dalitz processes of <math><mn>2</mn><mo>→</mo><mn>3</mn></math> and discuss the feasibility of detecting the <math><msub><mi>a</mi><mn>0</mn></msub><mo>(</mo><mn>1817</mn><mo>)</mo></math> meson in experiments like J-PARC.

Exploring kaon induced reactions for unraveling the nature of the scalar meson <math><mrow><msub><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>(</mo><mn>1817</mn><mo>)</mo></mrow></math>

Inspired by the recent near-threshold   $ J/\psi $  photoproduction measurements, we discuss gluon gravitational form factors (GFFs) and internal properties of the proton. This work presents a complete analysis of the proton gluon GFFs connecting the gluon part of the energy-momentum tensor and the heavy quarkonium photoproduction. In particular, a global fitting of the   $ J/\psi $   differential and total cross section experimental data is used to determine the gluon GFFs as functions of the squared momentum transfer t. Combined with the quark contributions to the D-term form factor extracted from the deeply virtual Compton scattering experiment, the total D-term is obtained to investigate their applications in describing the proton mechanical properties. These studies provide a unique perspective on investigating the proton gluon GFFs and important information for enhancing QCD constraints on the gluon GFFs.