Time-reversal asymmetries in Λ_(b)→Λ(→pπ^(−))ℓ^(+)ℓ^(−)  

作　　者：耿朝强 刘佳韦 魏正乙 Chao-Qiang Geng;Chia-Wei Liu;Zheng-Yi Wei(School of Fundamental Physics and Mathematical Sciences,Hangzhou Institute for Advanced Study,UCAS,Hangzhou 310024,China;University of Chinese Academy of Sciences,Beijing 100190,China;CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]School of Fundamental Physics and Mathematical Sciences,Hangzhou Institute for Advanced Study,UCAS,Hangzhou 310024,China [2]University of Chinese Academy of Sciences,Beijing 100190,China [3]CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Chinese Physics C》2024年第3期1-14,共14页中国物理C（英文版）

基　　金：Supported in part by the National Key Research and Development Program of China (2020YFC2201501);the National Natural Science Foundation of China (NSFC) (12147103)。

摘　　要：We study the decays ofΛb→Λ(→pπ^(−))ℓ^(+)ℓ^(−)withℓ=(e,μ,τ).We examine the full angular distributions with polarizedΛb,where the T-odd observables are identified.We discuss the possible effects of new physics(NP)and find that the T-odd observables are sensitive to them as they vanish in the standard model.Special attention is given to the interference of(pseudo)scalar operators with(axial)vector operators in polarized Λ_(b)→Λ(→pπ^(−))τ^(+)τ^(−),which are studied for the first time.Their effects are proportional to the lepton masses and therefore may evade the constraint from Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb naturally.AsΛ_(b)→Λ(→pπ^(−))τ^(+)τ^(−) is uncontaminated by the charmonia resonance,it provides a clean background to probe NP.In addition,we show that the experimental central value of K10 in Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb can be explained by the NP case,which couples to the right-handed quarks and leptons.The polarization fraction of Λ_(b) at the LHCb is found to be consistent with zero regardless of the NP scenarios.

关 键 词：time reversal asymmetry angular distribution new physics T-odd correlation 

分 类 号：O571[理学—粒子物理与原子核物理]