A few days ago Dr. Zhao Zhenxing from the School of Physical Science and Technology of IMU published significant findings in his research in a thesis entitled Novel Method to Reliably Determine the Photon Helicity in B → K1 γ in Physical Review Letters, a top-level international journal in the field of physical sciences, in which he proposed a novel method to determine the polarization of photon in the process of B → K1 γ. In his research, a “vertically asymmetrical ratio” is proposed in the process of semi-leptonic decay D → K1 e ν to quantitatively describe the hadron effect in the process of B → K1 so as to accurately extract the photon polarization in the process of B → K1 γ. It is highly hopeful that such photon polarization can be detected in accelerator experiments with BESIII, Belle-II and LHCb.

Standard models predict that the final state photons in the process of b→ s γ are mainly on the left hand, and the determination of the photon polarization in this decay model can be used in testing standard models and exploring novel physical effects. It has been noticed that the photon polarization in the process of B→K1 γ can be described as a “vertical asymmetry”, but since this physical quantity at the same time relies on information of the strong decay process K1→Kππ, this physical quantity alone is insufficient in determining the photon polarization in the process of B→K1 γ. The existing literature can only analyze the strong decay process K1→Kππ with the method of model dependence, which leads to great uncertainty in extracting the photon polarization in the process of B→K1 γ. Dr. Zhao Zhenxing and his collaborators point out that it is possible to extract the information of the strong decay of K1 through the semi-leptonic decay process D→K1(→Kππ) e ν to eventually determine the photon polarization in the process of B→ K1 γ.

The thesis also proposes possible methods to realize the determination in experiments. By dividing the decay width of B→Kππ γ and D→Kππ eν into two sections, namely cos (θK) >0 and cos (θK) <0, and fitting the Kππ mass spectrum through considering the contributions of different meson K resonance, the decay width of K1 in these two sections can be determined. The research also proposes the angular distribution formula for extracting photon polarization through the resonance of other mesons K.

Dr. Zhao Zhenxing is the correspondent author, and IMU is the correspondent unit of the thesis. Dr. Zhao’s collaborators are Prof. Wang Wei from Shanghai Jiaotong University and Prof. Yu Fusheng from Lanzhou University. Dr. Zhao Zhenxing graduated in September 2019 from Shanghai Jiaotong University with a doctorate of science, specializing in heavy flavor science and nonperturbative theories (QCD). Dr. Zhao was recruited onto a B2 post of the School of Physical Science and Technology of IMU in October 2019 under the Steed Program.