Fundamental Physics Seminar Series - Evolution of Helicity Property of Relic Neutrinos and Implications on Their Detection

Abstract

Neutrinos in the early Universe decoupled essentially in helicity eigenstates. As they propagate through the Universe, their helicities could be modified via two effects. First, neutrinos with a finite magnetic moment would rotate their spins with respect to their momenta as they encounter cosmic magnetic fields, modifying their helicities. Second, the bending of neutrino's spin by a gravitational field lags the bending of its momentum, again modifying its helicity. The speaker’s team studies both effects and investigates the implications of the helicity modification on the detection of relic neutrinos using the Inverse Tritium Beta Decay (ITBD) reaction. The team finds that the ITBD rate depends sensitively on the neutrino mass hierarchy and on the Dirac or Majorana nature of the neutrinos. This talk is based on several recent papers in collaboration with Gordon BAYM.


About the Speaker

Prof. PENG Jen-Chieh is Professor Emeritus in the Physics Department of University of Illinois at Urbana-Champaign. His research interests include the quark and antiquark structure of nucleons and nuclei, fundamental symmetries, and neutrino physics. He has conducted experiments at the AGS, LAMPF, Jefferson Laboratory, Fermilab, and CERN. He is the spokesperson or co-spokesperson for around 10 nuclear and particle physics experiments.


About the Center for Fundamental Physics

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


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