题 目： Bottom hadro-chemistry in high-energy proton-proton and heavy-ion collisions
报告人： 何 敏 （南京理工大学，教授）
邀请人： 秦思学
时 间： 2023年10月7号（星期六）下午 3:00
地 点： 理科楼 LE201
报告摘要：The hadrochemistry of bottom quarks (b) produced in hadronic collisions encodes valuable information on the mechanism of color neutralization in these reactions. Since the b-quark mass is much larger than the typical hadronic scale of ~1 GeV, b-bbar pair production is expected to be well separated from subsequent hadronization processes. A significantly larger fraction of b baryons has been observed in proton-proton (pp) and proton-antiproton (p-pbar) reactions relative to e^+e^- collisions, challenging theoretical descriptions. We address this problem by employing a statistical hadronization approach with an augmented set of b-hadron states beyond currently measured ones, guided by the relativistic quark model and lattice-QCD computations. Assuming relative chemical equilibrium between different b-hadron yields, thermal densities are used as fragmentation weights of b quarks into various hadron species. With quark model estimates of the decay patterns of excited states, the fragmentation fractions of weakly decaying b hadrons are computed and found to agree with measurements in p-pbar collisions at the Tevatron. By combining transverse-momentum (p_T) distributions of b quarks from perturbative QCD with thermal weights and independent fragmentation toward high pT, a fair description of the p_T-dependent B_s/B and Λ_b/B ratios measured in pp collisions at the LHC is obtained. The observed enhancement of Λ_b production is attributed to the feeddown from thus far unobserved excited b baryons. Finally, we implement the hadrochemistry into a strongly coupled transport approach for b quarks in heavy-ion collisions, utilizing previously determined b-quark transport coefficients in the quark-gluon plasma, to highlight the modifications of hadrochemistry and collective behavior of b hadrons in Pb-Pb collisions at the LHC. [Reference: M. He and R. Rapp, Phys. Rev. Lett. 131, 012301 (2023)]
报告人介绍：何敏，从事高能核物理理论科研和教学工作。2004年南京理工大学应用物理系学士，2009年南京大学物理系博士，2009年至2012年美国德州农工大学博士后。现任南京理工大学教授。
