Improved Measurement of the Form Factors and First Search for CP Violation in the Decay of Lambda_c^+ to Lambda e^+ nu_e
msra(2003)
摘要
Using the CLEO detector at the Cornell Electron Storage Ring we have studied
the angular distributions in the decay Lambda_c^+ to Lambda e+ nu_e. By
performing a four-dimensional maximum likelihood fit, we extract the form
factor ratio, R = f_2/f_1, and the pole mass, which determines the shape of the
form factors, M_{pole}. They are found to be -0.31 +/- 0.05_{stat} +/-
0.04_{syst}$ and (2.13 +/- 0.07_{stat} +/- 0.10_{syst}) GeV/c^2, respectively.
These results correspond to the following value of the decay asymmetry
parameter: alpha_{Lambda_c} = -0.85 +/- {0.03}_{stat} +/- 0.02_{sys}, for
更多= 0.67 (GeV/c^2)^2. We search for CP violation in the angular distributions of the decay and find no evidence for CP violation, obtaining anasymmetry ratio; A_{Lambda_{c}} = (alpha_{Lambda_c} + alpha_{\bar{Lambda}_c}) / (alpha_{Lambda_c} - alpha_{\bar{Lambda}_c}) = 0.01 +/- 0.03_{stat} +/- 0.01_{sys} +/- 0.02_{A_{Lambda}}, where the third error is from the uncertainty in the world average of the CP violating parameter, A_{Lambda}, for Lambda decay to p pi^-. All results presented in this paper are preliminary.
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关键词
form factor,cp violation,maximum likelihood
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