Precision hyperon physics at BESIII

by Dr Hai-Bo Li (IHEP)

Monday 18 Nov 2019, 15:30 → 17:00 Asia/Shanghai

5#/6th-603 - Meeting Room 603 (Science Building)

Abstract：

The CKM mechanism for CP violation in the Standard Model (SM) fails to explain the matter-antimatter asymmetry of the universe by more than 10 orders-of- magnitude. This suggests that additional CP violating processes occur, and motivates aggressive searches for new, non-SM sources of CP violation. To date, CP violation in hyperon decays have never been observed. Standard Model CP violations in hyperon decays are expected to be ∼ 10^-4 to 10^-5; any value higher than this level would be a signature of new, beyond the SM physics.

BESIII has collected about 10 billion J/psi decay events, the decay rate of J/psi to hyperon-anti-hyperon pairs are 10^-3, which indicates that the produced hyperon pairs will be a few millions. In this talk I will present the first observation of transverse polarization of hyperon-anti-hyperon from the e+e- --> J/psi --> hyperon-anti-hyperon pairs, which allows us to measure the decay asymmetry parameters of both hyperon and anti-hyperon, therefore CP asymmetry in the hyperon decay can be precisely obtained with 5 dimensional fit to data. We expect that the study of hyperon physics will be the next frontier of the SM CP searches.

Biography:

In 1998, I obtained my Ph.D degree from IHEP in China, then joined CERN ALEPH experiment as a CERN Asia Fellow in 1999.

In 2001, as a research associate from University Wisconsin at Madison, I joined BaBar experiment at its earlier stage.

I worked on the measurements of CP violation in the B decay, and finished the first measurement of sin(2 alpha)_effective, which si a milestone of CPV in B decay. In 2005, I joined BESIII experiment, and worked on the BESIII physics book, and preparation of BESIII physics before its starting in 2009. Then as the first physics analysis coordinator of BESIII Collaboration, I pushed the first publication of BESIII paper. At BESIII, I mainly worked on the Charmed meson and baryon decays, and search for New physics with high statistical data at low energy.

In 2012, a group from IHEP joined COMET experiment to work on the physics of muon to electron conversion, I am the leader of COMET group in China now.