Abstract: A light CP-even scalar S with mass below GeV-scale exists in may beyond standard model (SM) scenarios. Such a light particle can be produced abundantly in the stars, such as the Sun, red giants, white dwarfs, horizontal-branch stars, neutron star mergers, and supernovae. In this talk I will show the state-of-art stellar limits on S. Assuming the couplings of S to the SM particles are from mixing with the SM Higgs, the production of S will be dominated by nucleon bremsstrahlung process in all the stars. With the decay and reabsorption of S taken into consideration, the stellar luminosities exclude a broad range of the mixing angle, from 
to 
, with the scalar mass up to roughly order of 100 MeV. These stellar limits are largely complementary to other laboratory, astrophysical and cosmological limits on S.
报告人简介：张永超博士于2014年在北京大学获得博士学位，在访问中科院理论物理研究所一年之后，张永超博士于2015 – 2017年在布鲁塞尔自由大学（Université Libre de Bruxelles）做博士后，之后于2017 – 2020年在美国圣路易斯华盛顿大学（Washington University in St. Louis）做博士后。张永超博士于今年11月份刚刚受聘为东南大学的副教授。
