Events on Monday, November 25th, 2024
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Extreme Plasmas around Black Holes and Neutron Stars
- Time: 12:05 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Sasha Philippov, University of Maryland and SCEECS
- Abstract: Astrophysical compact objects, such as neutron stars and black holes, are powerful sources of non-thermal electromagnetic emission spanning many orders of magnitude in photon energy, from radio waves to multi-TeV gamma-rays, and, potentially, of high-energy neutrinos and cosmic rays. Despite multiple groundbreaking observational discoveries done in recent years, our understanding of the dynamics of relativistic plasmas that produce these multi-messenger signatures remains limited. In this talk, I will describe the activities of the recently started Simons Collaboration on Extreme Electrodynamics of Compact Sources (SCEECS) aiming at producing first-principles descriptions of relativistic and radiative plasmas near compact objects. I will show a few examples of modeling the observed light coming from these remarkable astrophysical laboratories using numerical simulations.
- Host: Vladimir Zhdankin and John Sarff
- Thesis Defense
- Search for dark matter produced in association with top quarks at the Compact Muon Solenoid}
- Time: 4:30 pm - 6:00 pm
- Place: 5280 CH or
- Speaker: Victor Shang, Physics PhD Graduate Student
- Abstract: One of the fundamental open questions that cannot be currently explained by the Standard Model is the particle nature of dark matter. Though astrophysical observations provide indirect evidence of its existence, dark matter has not been directly measured so far. However, under certain assumptions, dark matter may be possible to produce and detect at high energy particle colliders like the LHC.
This thesis presents a search for dark matter produced in association with top quarks in data collected by the CMS detector at the LHC, corresponding to 138 fb-1 of proton-proton collisions at a center-of-mass energy of 13 TeV. Production of dark matter particles in association with both a single top quark and a pair of top quarks are considered. The search is performed in three separate channels depending on the number of leptons in the final state, which include the all hadronic, single lepton, and dileptonic final states. The primary strategy of the search is to look for an excess of events with respect to the background-only prediction in events with a large imbalance in the transverse momentum. The results are interpreted in the context of a simplified model in which either a scalar or pseudoscalar mediator couples to top quarks and to dark matter fermions. Future prospects for improving the search are also discussed - Host: Tulika Bose