期刊
PHYSICAL REVIEW LETTERS
卷 129, 期 13, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.129.131801
关键词
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资金
- National Key R&D Program of China [2020YFA0406300, 2020YFA0406400]
- National Natural Science [12192264, 12192265]
- Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program
- NSFC [U1832207]
- CAS [U1832207]
- CAS Key Research Program of Frontier Sciences [QYZDJ-SSW-SLH040]
- 100 Talents Program of CAS
- INPAC
- Shanghai Key Laboratory for Particle Physics and Cosmology
- Polish National Science Centre [2019/35/O/ST2/02907]
- ERC [758462]
- European Union [894790]
- German Research Foundation DFG [443159800, CRC 1044, GRK 2149]
- Istituto Nazionale di Fisica Nucleare, Italy
- Ministry of Development of Turkey [DPT2006K-120470]
- National Science and Technology fund
- STFC (United Kingdom)
- Royal Society, UK [DH140054, DH160214]
- Swedish Research Council
- U.S. Department of Energy [DE-FG02-05ER41374]
- Marie Curie Actions (MSCA) [894790] Funding Source: Marie Curie Actions (MSCA)
Based on 10 billion J/psi events collected at the BESIII experiment, a search for CP violation in Lambda decay is performed. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined, and the average decay parameter values for Lambda and (Lambda) over bar are extracted with unprecedented accuracy. These results play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.
Based on 10 billion J/psi events collected at the BESIII experiment, a search for CP violation in Lambda decay is performed in the difference between CP-odd decay parameters alpha_ for Lambda -> p pi(-) and alpha(+) for (Lambda) over bar -> (p) over bar pi(+) by using the process e(+)e(-) -> J/psi -> Lambda(Lambda) over bar. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters arc determined to be a_ = 0.7519 +/- 0.0036 +/- 0.0024 and alpha(+) = -0.7559 +/- 0.0036 +/- 0.0030, respectively. The Lambda and (Lambda) over bar averaged value of the decay parameter is extracted to be a(avg) = 0.7542 +/- 0.0010 +/- 0.0024 with unprecedented accuracy. The CP asymmetry A(CP) = (alpha_ + alpha(+))/(a_-alpha(+)) is determined to be -0.0025 +/- 0.0046 +/- 0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.
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