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)

When an energetic parton traverses the hot QCD medium, it may suffer from multiple scattering and lose its energy. The medium-induced gluon radiation for a massive quark will be suppressed relative to that of a light quark due to the dead-cone effect. The development of new declustering techniques of jet evolution makes a direct study of the dead-cone effect in the QCD medium possible for the first time. In this work, we compute the emission angle distribution of the charm-quark-initiated splittings in $\textit{D}$ $^{0}$ meson tagged jet and that of the light parton-initiated splittings in an inclusive jet in $\textit{p}$+$\textit{p}$ and Pb+Pb at 5.02 TeV by utilizing the declustering techniques of jet evolution. The heavy quark propagation and induced energy loss in the QCD medium are simulated with the SHELL model based on the Langevin equation. By directly comparing the emission angle distributions of charm-quark-initiated splittings with those of light parton-initiated splittings at the same energy intervals of the initial parton, we provide insights into the fundamental splitting structure in $\textit{A}$+$\textit{A}$ collisions, thereby exploring the possible observation of the dead-cone effect in medium-induced radiation. We further investigate the case of the emission angle distributions normalized to the number of splittings and find the dead-cone effect will broaden the emission angle of the splitting and reduce the possibility for such splitting to occur, leading the massive parton to lose less energy. We also find that the collisional energy loss mechanism has a negligible impact on the medium modification to the emission angle distribution of the charm-quark-initiated splittings for $\textit{D}$ $^{0 }$meson-tagged jets.

Yun-Fan Liu

Wei Dai

Exposing the dead-cone effect of jet quenching in QCD medium * Supported by the Major Project of Basic and Applied Basic Research of Guangdong Province, China (2020B0301030008), and the Natural Science Foundation of China (1935007, 11805167)

<p>We implement a variational quantum algorithm to investigate the chiral condensate in a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn></mrow></math> dimensional SU(2) non-Abelian gauge theory. The algorithm is evaluated using a proposed Monte Carlo sampling method, which allows the extension to large qubit systems. The obtained results through quantum simulations on classical and actual quantum hardware are in good agreement with exact diagonalization of the lattice Hamiltonian, revealing the phenomena of chiral symmetry breaking and restoration as functions of both temperature and chemical potential. Our findings underscore the potential of near-term quantum computing for exploring QCD systems at finite temperature and density in non-Abelian gauge theories.</p>

Guofeng Zhang

Xingyu Guo

Hongxi Xing

Quantum computing of chirality imbalance in SU(2) gauge theory

<p>This paper presents a theoretical study on the production of leptons from decay of heavy-flavor hadrons (denoted as HFLs) in high-energy nuclear collisions at the CERN Large Hadron Collider. The <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">pp</mi></math> baseline is calculated by the fonll program, which matches the next-to-leading order perturbative QCD (pQCD) calculation with the next-to-leading-logarithm large-<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math> resummation. The in-medium propagation of heavy quarks is driven by the modified Langevin equations, which consider both the elastic and inelastic partonic interactions. We propose a method to separate the respective influence of the six factors, i.e., <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">pp</mi></math> spectra, cold nuclear matter (CNM) effects, in-medium energy loss (E-loss), fragmentation functions (FFs), coalescence (Coal), and decay channels, which may contribute to the larger <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math> of HFL <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>←</mo><mi>b</mi></mrow></math> compared to that of HFL <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>←</mo><mi>c</mi></mrow></math> in nucleus-nucleus collisions. Based on quantitative analysis, we demonstrate that both coalescence hadronization decay channels and the mass-dependent E-loss play an essential role at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>p</mi><mi>T</mi></msub><mo>&lt;</mo><mn>5</mn><mspace width="0.16em"></mspace><mi>GeV</mi></mrow></math>, while the latter dominates the higher <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math> region. It is also found that the influences of the CNM effects and FFs are insignificant. At the same time, different initial <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">pp</mi></math> spectra of charm and bottom quarks have a considerable impact at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>p</mi><mi>T</mi></msub><mo>&gt;</mo><mn>5</mn><mspace width="0.16em"></mspace><mi>GeV</mi></mrow></math>. Furthermore, we explore the path-length dependence of jet quenching by comparing the HFL <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math> in two different collision systems. Our investigations show smaller HFL <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math> in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> than in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Xe</mi><mo>+</mo><mi>Xe</mi></mrow></math> within the same centrality bin, consistent with the ALICE data. The longer propagation time and more effective energy loss of heavy quarks in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions play critical roles in the stronger yield suppression of the HFLs compared to that in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Xe</mi><mo>+</mo><mi>Xe</mi></mrow></math>. In addition, we observe a scaling behavior of the HFL <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>R</mi><mrow><mi>A</mi><mi>A</mi></mrow></msub></math> in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Xe</mi><mo>+</mo><mi>Xe</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions.</p>

Shuwan Shen

Production of leptons from decay of heavy-flavor hadrons in high-energy nuclear collisions

Studies of exotic hadrons such as the <math><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mrow><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></mrow></math> state provide crucial insights into the fundamental force governing the strong interaction dynamics, with an emerging frontier to investigate their production in high energy collisions where a partonic medium is present. The latest experimental measurements from the Large Hadron Collider show an intriguing evolution pattern of the <math><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mrow><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></mrow></math>-to-<math><mrow><mi>ψ</mi><mo>(</mo><mn>2</mn><mi>S</mi><mo>)</mo></mrow></math> yield ratio from proton-proton collisions with increasing multiplicities toward proton-lead and lead-lead collisions. Here we propose a mechanism of medium-assisted enhancement for the <math><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mrow><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></mrow></math> production, which competes with the more conventional absorption-induced suppression and results in a nonmonotonic trend from small to large colliding systems. Realistic simulations from this model offer a quantitative description of all available data. Predictions are made for the centrality dependence of this observable in PbPb collisions as well as for its system-size dependence from OO and ArAr to XeXe and PbPb collisions. In both cases, a nonmonotonic behavior emerges as the imprint of the competition between enhancement and suppression and can be readily tested by future data.

Yu Guo

United States

Jinfeng Liao

Medium-assisted enhancement of <math><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mrow><mo>(</mo><mn>3872</mn><mo>)</mo></mrow></mrow></math> production from small to large colliding systems

We investigate the impact of the magnetic field generated by colliding nuclei on heavy quark-antiquark interactions and heavy quark dynamics in the quark-gluon plasma (QGP). By means of the hard-thermal-loop resummation technique combined with dimension-two gluon condensates, the static heavy quark potential and heavy quark momentum diffusion coefficient, which incorporate both perturbative and nonperturbative interactions between heavy quarks and the QGP medium, are computed beyond the lowest Landau level approximation. We find that the imaginary part of the heavy quark potential in the magnetic field exhibits significant anisotropy. Specifically, the absolute value of the imaginary part is larger when the quark-antiquark separation is aligned perpendicular to the magnetic field direction, compared to when it is aligned parallel to the magnetic field direction. The heavy quark momentum diffusion coefficient in the magnetized QGP medium also becomes anisotropic. As the temperature rises, the influence of higher Landau levels becomes increasingly significant, resulting in a decrease in the anisotropy ratio of the heavy quark momentum diffusion coefficient to values even below 1. At sufficiently high temperatures, this ratio ultimately approaches 1. The nonperturbative interactions are indispensable for understanding heavy quark dynamics in the low-temperature region. We also study the response of viscous quark matter to the magnetic field and explore its implications for heavy quark potential, thermal decay widths of quarkonium states, as well as heavy quark momentum diffusion coefficient.

He-Xia Zhang

Responses of quark-antiquark interactions and heavy quark dynamics to magnetic fields

We investigate the flavor dependence of jet quenching, by performing a systematic analysis of medium modifications on the inclusive jet, γ+jet, and b-jet in Pb+Pb collisions at the LHC. Our results from MadGraph+PYTHIA exhibit excellent agreement with experimental measurements of the inclusive jet, γ+jet and b-jet simultaneously in p+p collisions. We then utilize a Bayesian data-driven method to extract systematically the flavor-dependent jet energy loss distributions from experimental data, where the gluon, light quark and b-quark initiated energy loss distributions are well constrained and satisfy the predicted flavor hierarchy of jet quenching, i.e. <math><mo>〈</mo><mi>Δ</mi><msub><mrow><mi>E</mi></mrow><mrow><mi>g</mi></mrow></msub><mo>〉</mo><mo>&gt;</mo><mo>〈</mo><mi>Δ</mi><msub><mrow><mi>E</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>〉</mo><mo>&gt;</mo><mo>〈</mo><mi>Δ</mi><msub><mrow><mi>E</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>〉</mo></math>. It is shown that the quark-initiated jet energy loss distribution shows weaker centrality and <math><msub><mrow><mi>p</mi></mrow><mrow><mtext>T</mtext></mrow></msub></math> dependence than the gluon-initiated one. We demonstrate the impacts of the slope of initial spectra, color-charge as well as parton mass dependent jet energy attenuation on the <math><mi>γ</mi><mo>/</mo><mi>b</mi></math>-jet suppression observed in heavy-ion collisions.

Shan-Liang Zhang

Flavor dependence of jet quenching in heavy-ion collisions from a Bayesian analysis

Utilizing the Lehmann-Symanzik-Zimmermann reduction formula, we present a new general framework for computing scattering amplitudes in quantum field theory with quantum computers in a fully nonperturbative way. In this framework, one only has to construct one-particle states of zero momentum, and no wave packets of incoming particles are needed. The framework is able to incorporate scatterings of bound states, and is ideal for scatterings involving a small number of particles. We expect this framework to have particular advantages when applied to exclusive hadron scatterings. As a proof of concept, by simulations on classical hardware, we demonstrate that in the one-flavor Gross-Neveu model, the fermion propagator, the connected fermion four-point function, and the propagator of a fermion-antifermion bound state obtained from our proposed quantum algorithm have the desired pole structure crucial to the implementation of the Lehmann-Symanzik-Zimmermann reduction formula.

Tianyin Li

Wai Kin Lai

Scattering amplitude from quantum computing with reduction formula

The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect. In this paper, we present the first theoretical study on the angular correlations (  $ \Delta\phi_{bZ} $  ), transverse momentum imbalance (  $ \Delta\phi_{bZ} $  ), and nuclear modification factor (  $ \Delta\phi_{bZ} $  ) of   $ \Delta\phi_{bZ} $   boson tagged b-jets in heavy-ion collisions, which was performed using a Monte Carlo transport model. We find that the medium modification of the   $ \Delta\phi_{bZ} $   for   $ \Delta\phi_{bZ} $   + b-jet has a weaker dependence on   $ \Delta\phi_{bZ} $   than that for   $ \Delta\phi_{bZ} $   + jet, and the modification patterns are sensitive to the initial jet   $ \Delta\phi_{bZ} $   distribution. Additionally, with the high purity of the quark jet in   $ \Delta\phi_{bZ} $   + (b-) jet production, we calculate the momentum imbalance   $ \Delta\phi_{bZ} $   and the nuclear modification factor   $ \Delta\phi_{bZ} $   of   $ \Delta\phi_{bZ} $   + b-jet in Pb+Pb collisions. We observe a smaller   $ \Delta\phi_{bZ} $   and larger   $ \Delta\phi_{bZ} $   of   $ \Delta\phi_{bZ} $   + b-jet in Pb+Pb collisions relative to those of   $ \Delta\phi_{bZ} $   + jet, which may be an indication of the mass effect of jet quenching and can be tested in future measurements.

  Boson Associated -jet Production in High-energy Nuclear Collisions  

Recently, the LHCb Collaboration observed a doubly charmed tetraquark candidate <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math> and claimed its isospin to be zero due to the absence of <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup></math>. However, the absence of the <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup></math> in the LHCb experiment may be due to their low yield in <math><mi>p</mi><mi>p</mi></math> collisions; thus, the isospin of <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math> still needs to be clarified. We propose an efficient way to investigate the isospin property of <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math> from the Dalitz plot distribution of <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup><mo>→</mo><msup><mi>D</mi><mo>+</mo></msup><msup><mi>D</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup></math>. This method can also be applied to other exotic candidates.

Jun Shi

Qian Wang

Investigating the isospin property of <math><msubsup><mi>T</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math> from its Dalitz plot distribution