报告题目：gluo-dissociaton of heavy quarkonium and heavy baryon versus heavy meson ratio 

　　报告人：Dr. Min He (何敏) 南京理工大学 

　　时间安排：2017年8月11日15:00         

　　地点：近代物理所5号楼1006会议室 

　　报告摘要:  

　　Heavy quarks (open heavy flavor) and heavy quarkonia (hidden heavy flavor) are valuable probes of the hot medium created in relativistic heavy-ion collisions. This talk consists of two distinct works about hidden and open heavy flavor probes, respectively. In the first part, I will present our recent revisit to the gluo-dissociation of heavy quarkonia in the quark-gluon plasma. Within the theoretical framework of QCD multiple expansion, gluo-dissociaton cross secton of various charmonia and bottomonia are newly and systematically derived and evaluated using quantum mechanical perturabation method. Notable is the inclusion and evaluation of a new (chromo-magnetic dipole) mechanism of gluo-dissocation, in addition to the traditional chromo-electric dipole transtion. The contribution of the former to the charmonium dissocation rate turns out to be significant for $\J\psi$ dissociation at temperatures close to $T_{\rm pc}$. 

　　In the second part of the talk, I will present our recent calculation of the heavy baryon ($\Lambda_c$) and the heavy meson ($D_0$) ratio at RHIC and LHC energies, using realistic charm quark and light quark spectra. We first calculate the various light baryon over meson ratio in the coalescence plus fragmentation model and reproduce the experimentally observed enhancement at intermediate pT. Gaining constraints on the model as well as the light quark spectra this way, we further calcualte the $\Lambda_c$ over $D_0$ ratio within the same framework, arguing it to be a sensitive measure of the degree of the charm quark thermaliztion. In particular, we will compare the results from instantaneous coalescence model and a resonance recombination model.