"Discrete (Family) Symmetries and Origin of CP Violation," by Mu-Chun Chen (UC Irvine)

Monday, February 13, 2017 - 3:00pm to 4:00pm
TEPAPP Seminars

Theory of Elementary Particles, Astroparticle Physics, and Phenomenology (TEPAPP) Seminar

Physics & Astronomy Building (PAB) Room 4-330
Monday, February 13, 2017

Guest Speaker: Mu-Chun Chen (UC Irvine)​

Talk Title: "Discrete (Family) Symmetries and Origin of CP Violation"


The origins of the flavor mixing and CP violation remain a mystery in particle physics. The discovery of non-zero neutrino masses leads to yet another puzzle: why the neutrino masses are so small when compared to other fermions, and why two of the three neutrino mixing angles are so large when compared with their quark counterpart. Furthermore, CP violation in the Standard Model is insufficient to explain the observed cosmological baryon number asymmetry. On the other hand, the recent observation of a large value for the third neutrino mixing angle implies good future experimental prospects for discovering a new source of CP violation in the neutrino sector. This new CP violation source may be relevant for the dynamical generation of the cosmological matter-antimatter asymmetry.

In this talk, I will discuss how these outstanding questions in particle physics can be addressed by new physics beyond the Standard Model. In particular, I will focus on models based on discrete family symmetries which give rise to realistic masses and mixing angles of all observed fermions, including the neutrinos, with a significantly reduced number of parameters. I will point out a novel interesting possibility that for certain discrete symmetries, CP violation can be entirely group theoretical in origin. Specifically, we show that physical CP transformations always have to be class-inverting automorphisms of G. We also show that certain operations that have been dubbed generalized CP transformations in the recent literature do not lead to physical CP conservation. It is found that discrete groups can be classified into three types, each with different implications for CP violation.

Event Attachments: 
PAB 4-330