In this study, we investigate the $R^2$ corrections to the dissociation of heavy quarkonium in the Gauss-Bonnet gravitational background. We analyze the impact of the Gauss-Bonnet parameter $\lambda_{\rm GB}$ on the spectral function of charmonium and bottomonium and examine the effect of $\lambda_{\rm GB}$ on the dissociation of heavy quarkonium. Our results show that $\lambda_{\rm GB}$ reduces the peak height and increases the peak width of the spectral function, suggesting that $\lambda_{\rm GB}$ enhances the dissociation of heavy quarkonium. We also discuss the variation in the dissociation of heavy quarkonium with the ratio of shear viscosity to entropy density and observe that the dissociation is easier in more perfect plasma. Additionally, we observe that the temperature decreases the peak height and widens the peak, thereby accelerating the dissociation.

China

Zhou-Run Zhu

Manman Sun

Rui Zhou

Jinzhong Han

$\textit{R}$ $^{2}$ corrections to holographic heavy quarkonium dissociation * Rui Zhou supported by the Science and Technology Development Plan Project of Henan Province, China (242102230085), the National Natural Science Foundation of China (12404470), the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023017). Manman Sun supported by the National Natural Science Foundation of China (12305076). Zhou-Run Zhu supported by the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023018)

We study the transverse momentum ( $p_T$ ) differential anisotropic flow and flow fluctuation in Pb+Pb collisions at $\sqrt{s_{_{NN}}}$ =5.02 TeV at the LHC. A (3+1)-dimensional CLVisc hydrodynamics framework with fluctuating TRENTO (or AMPT) initial conditions is utilized to simulate the space-time evolution of the quark-gluon plasma (QGP) medium. The effects of shear viscosity and the sub-nucleon structure on anisotropic flow and flow fluctuation are analyzed. Our result shows that shear viscosity tends to suppress both flow coefficients ( ${v_2\{2}\}$ , ${v_2\{4\}}$ , and ${\langle v_2\rangle}$ ) and flow fluctuation ( ${\sigma_{v_2}}$ ) owing to its smearing effect on local density fluctuation. The flow coefficients appear to be insensitive to the sub-nucleon structure, whereas the flow fluctuation ${\sigma_{v_2}}$ tends to be suppressed by the sub-nucleon structure in central collisions but enhanced in peripheral collisions. After taking into account the sub-nucleon structure effect, our numerical result can qualitatively describe the relative flow fluctuations ( ${v_2\{4\}/v_2\{2\}}$ , $F({v_2})$ ) measured by the ALICE Collaboration at the LHC. We further investigate the effects of shear viscosity, sub-nucleon structure, and initial condition model on the flow angle and flow magnitude decorrelations ( ${A_2^f}$ , ${M_2^f}$ ) using the four-particle correlation method. We find that the flow decorrelation effect is typically stronger in central collisions than in peripheral collisions. The flow angle decorrelation is found to be insensitive to the shear viscosity and sub-nucleon structure, whereas the flow magnitude decorrelation shows quite different behaviors when using the TRENTO and AMPT initial condition models. Our study sheds light on the anisotropic flow, transport properties, and initial structure of the QGP created in high-energy nuclear collisions.

Germany

Jie Zhu

Canada

Xiang-Yu Wu

Guang-You Qin

Anisotropic flow, flow fluctuation, and flow decorrelation in relativistic heavy-ion collisions: the roles of sub-nucleon structure and shear viscosity * Supported in part by the Natural Science Foundation of China (12225503, 11890710, 11890711, 11935007). Zhu Jie is supported in part by the China Scholarship Council (202306770009). Wu Xiang-Yu is supported in part by the National Science Foundation within the framework of the JETSCAPE collaboration (OAC-2004571) and in part by the Natural Sciences and Engineering Research Council of Canada. Some of the calculations were performed in the Nuclear Science Computing Center at Central China Normal University (NSC$^{3}$), Wuhan, Hubei, China.

From the data on baryon production in heavy-ion collisions it is shown that a set of measurable functions exist, one for each baryon type, that depends exponentially on transverse momenta up to the maximum values detected for all collision energies ranging from the low end of the BNL Relativistic Heavy Ion Collider Beam Energy Scan to the high end of the CERN Large Hadron Collider. The implied temperatures satisfy a scaling law in collision energy with a universal exponent for all baryon types which is the novel discovery. A self-similar thermal source is implied. Furthermore, it is shown how the scaling behavior depends on centralities. Those features in the data are related to simple properties of light and strange quarks by use of the recombination model. Prediction of <math><mi>ϕ</mi></math> meson production is made and then verified by existing data.

Lilin Zhu

Hua Zheng

Ke Da

Huanjing Gong

Zhizhen Ye

Guiqi Liu

United States

Rudolph C. Hwa

Universal energy dependence of measured temperatures for baryons produced in heavy-ion collisions

The transverse momentum spectra of seven identified hadrons produced in <math><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>2.76</mn></mrow></math> and 5.02 TeV at the CERN Large Hadron Collider have been investigated in the framework of the recombination model (RM). Soft, semihard, and hard partons all play important roles in our model and are uniformly treated for all hadrons produced. The investigation has been extended to noncentral collisions and the parameters controlling the momentum degradation of semihard partons have been tuned. Our study shows good agreement between theoretical results and experimental data. To be able to provide a coherent explanation for the production of all identified hadrons (<math><mi>π</mi><mo>,</mo><mo> </mo><mi>p</mi><mo>,</mo><mo> </mo><mi>K</mi><mo>,</mo><mo> </mo><mi>Λ</mi><mo>,</mo><mo> </mo><mi>ϕ</mi><mo>,</mo><mo> </mo><mi>Ξ</mi><mo>,</mo><mo> </mo><mi>Ω</mi></math>) for transverse momenta as high as 14 <math><mrow><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math> (for <math><mi>π</mi><mo>,</mo><mo> </mo><mi>p</mi></math>, and <math><mi>K</mi></math>), and for all centralities, is an unprecedented achievement that supports the RM as a sensible model to combine various mechanisms of parton production with a universal scheme of hadronization.

Centrality and transverse-momentum dependence of hadrons in <math><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at energies available at the CERN Large Hadron Collider

We compare two types of Tsallis distribution, that is, with and without thermodynamical description, using the experimental data from the STAR, PHENIX, ALICE, and CMS Collaborations on the rapidity and energy dependence of the transverse momentum spectra in <math id="M2"><mi>p</mi><mo>+</mo><mi>p</mi></math> collisions. Both of them can fit the particle spectra well. We show that the Tsallis distribution with thermodynamical description gives lower temperatures than the ones without it. The extra factor <math id="M3"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> (transverse mass) in the Tsallis distribution with thermodynamical description plays an important role in the discrepancies between the two types of Tsallis distribution. But for the heavy particles, the choice to use <math id="M4"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> or <math id="M5"><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> (transverse energy) in the Tsallis distribution becomes more crucial.

Italy

H. Zheng

Comparing the Tsallis Distribution with and without Thermodynamical Description in Collisions

The Tsallis distribution has been tested to fit all the particle spectra at mid-rapidity from central events produced in d + Au, Cu + Cu, and Au + Au collisions at RHIC and p + Pb, Pb + Pb collisions at LHC. Even though there are strong medium effects in Cu + Cu and Au + Au collisions, the results show that the Tsallis distribution can be used to fit most of particle spectra in the collisions studied except in Au + Au collisions where some deviations are seen for proton and <math id="M1"><mrow><mi>Λ</mi></mrow></math> at low <math id="M2"><mrow><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math>. In addition, as the Tsallis distribution can only fit part of the particle spectra produced in Pb + Pb collisions where <math id="M3"><mrow><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> is up to 20 GeV/c, a new formula with one more fitting degree of freedom is proposed in order to reproduce the entire <math id="M4"><mrow><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> region.

Can Tsallis Distribution Fit All the Particle Spectra Produced at RHIC and LHC?