Topic: Supernova Constraints on Millicharged Particles and Lepton-Flavor-Violating Axions

Speaker: Prof.Zuowei Liu

Coordinates: PCFT C1124, 16:00, Tuesday, June 16

Abstract: This talk will present supernova (SN) constraints on millicharged particles (MCPs) and lepton-flavor-violating (LFV) axions. We consider both the traditional SN cooling limits and the low-energy supernova (LESN) constraints, the latter of which use the explosion energies of low-energy supernovae to bound the amount of energy transported from the SN core to the stellar mantle. For MCP production in the SN core, we compute the electron-positron annihilation process for the first time and find that it dominates over plasmon decay and proton bremsstrahlung in the high-mass regime. We also incorporate the thermal-pion–initiated production channels recently proposed in the literature and quantify their impact. For LFV axions that couple to electrons and muons, we evaluate the electron-muon coalescence process for the first time and find that it is the leading production mechanism in the high-mass regime, exceeding the contributions from both muon decay and semi-Compton scattering. Overall, we find that LESN constraints provide the most stringent bounds in the high-mass regime for both MCPs and LFV axions, thereby probing regions of parameter space beyond the reach of conventional SN cooling arguments and terrestrial experiments. 

Speaker Profile: 刘佐伟，南京大学物理学院教授。2003年本科毕业于复旦大学；2008年博士毕业于美国东北大学；2008年至2014年先后在美国纽约州立大学石溪分校杨振宁理论物理研究所和加拿大麦吉尔大学从事博士后研究；2014年至2016年在清华大学任副研究员；2016年至今在南京大学任教授。主要从事粒子理论研究，研究兴趣包括暗物质理论与唯象学、天体物理环境与加速器实验中的新物理探测。迄今发表学术论文50余篇，累计被引用3000余次，单篇最高被引用400余次。