An improved method for determining the electric dipole moment of Lambda hyperon

作者：Zhang F; Gao Y^*; Huo L

来源：Physics Letters B, 2009, 681(3): 237-239.

DOI：10.1016/j.physletb.2009.10.019

• CP conservation
• Electric dipole moment

A CP-odd observable has been proposed by He and collaborators to test the CP conservation in J/psi -> Lambda(Lambda) over bar and its expectation value can be used to determine the electric dipole moment of Lambda [X.G. He, J.P. Ma, B. McKellar, Phys. Rev. D 47 (1993) R1744; X.G. He, J.P. Ma, B. McKellar, Phys. Rev. D 49 (1994) 4548]. Instead of measuring the expectation value of the CP-odd observable directly, we proposed an indirect method which can significantly improve the statistical sensitivity. With this improved method, Monte Carlo studies show that an expected upper limit of 0.4 x 10(-16) e cm on the electric dipole moment of Lambda can be obtained based on 10(4) fully reconstructed J/psi -> Lambda(Lambda) over bar, Lambda -> p pi(-),(Lambda) over bar -> (p) over bar pi(+) events. This expected tipper limit is about a factor 4 smaller than the one obtained from the direct experimental search to date. The result Suggests an unprecedented experimental sensitivity on detecting the electric dipole moment of Lambda could be reached even with the data sample already collected by BESII.

• 出版日期2009-11-2
• 单位哈尔滨工业大学; 清华大学