Fundamental Physics Seminar Series - Constraints on Symmetric Dark Matter from Neutron Star Capture and Collapse

Abstract

Neutron stars are known to constrain asymmetric dark matter because accumulated particles can trigger collapse. The speaker will show that these constraints extend much further: even when dark matter is produced with equal particle and antiparticle abundances, the capture process inside a neutron star can become intrinsically asymmetric if the two species scatter off nucleons with slightly different strengths. This difference arises naturally from interference between interaction terms with specific charge-conjugation properties, and turns out to be generic across the full set of allowed dark matter–nucleon couplings. As a result, neutron stars can exclude extremely small scattering rates over a wide mass range, and the constraints remain effective even when the capture asymmetry is tiny. Neutron stars probe not only abundance asymmetries but also the microscopic structure of dark matter interactions, significantly broadening their impact on dark matter theory.


About the Speaker

Mr. LIU Yuxin will get his PhD in the summer of 2026 in Theoretical Physics at the International Centre for Theoretical Physics Asia-Pacific (ICTP-AP), University of Chinese Academy of Sciences. He will soon move to Fermilab as a Postdoc Fellow. He received his BS in Mathematics and Physics from Tsinghua University in 2021 and has held visiting positions at The University of Utah and the University of Minnesota. His research focuses on dark matter searches, high-energy phenomenology and model building, gravitational-wave phenomenology, and fundamental physics probed through neutron stars, black holes, and terrestrial precision experiments.


About the Center for Fundamental Physics

For more information, please refer to https://cfp.hkust.edu.hk/.


For Attendees' Attention

Seating is on a first come, first served basis.