CP conservation in the strong interactions

by Prof. Dr. Björn Garbrecht (Technical University of Munich)

Thursday 22 Oct 2026, 11:00 → 12:00 Asia/Shanghai

Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee Institute)

Abstract：

In this talk, I will show that the principles of functional as well as canonical quantization applied to Yang--Mills theory lead to the conclusion that the CP-odd theta term is physically irrelevant. I will then discuss how this fits into the picture of QCD with massive quarks, in particular that there is no conflict between CP conservation for general values of theta and the absence of a light U(1)_A boson.

Biography：

Academic Career and Research Areas

The group of Professor Garbrecht (b. 1977) performs research on particle physics processes in the early universe. The challenge is that often these cannot be considered as isolated scattering processes. This may be due to the finite temperature after the Big Bang or due to the strongly curved space-time at this time. For this purpose, Professor Garbrecht's group develops methods of describing high-energy reactions out of thermal equilibrium as well as quantum fields in expanding space-times. An important application is the dynamical generation of the matter-antimatter asymmetry of the universe, for which a deviation from thermal equilibrium is a necessary condition. Of particular interest are models that establish a connection with experimental tests of charge-parity violation, of electroweak symmetry breaking and neutrino oscillations.

Björn Garbrecht studied physics in Heidelberg and at the University of Massachusetts, Amherst. After obtaining his doctorate from Heidelberg in 2005 he went on to become a postdoctoral researcher in Manchester, UK, and at the University of Wisconsin–Madison. From 2009 to 2012 he held the position of assistant professor and led a research group at RWTH Aachen. In 2012, he was appointed professor at TUM.

Alternative online link：https://meeting.tencent.com/dm/kebn593EKx9H

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