Hinson J W, Huang G S, Lee J, Miller D H, Pavlunin V, Rangarajan R, Sanghi B, Shibata E I, Shipsey I P J, Cronin-Hennessy D, Park C S, Park W, Thayer J B, Thorndike E H, Coan T E, Gao Y S, Liu F, Stroynowski R, Artuso M, Boulahouache C, Blusk S, Dambasuren E, Dorjkhaidav O, Mountain R, Muramatsu H, Nandakumar R, Skwarnicki T, Stone S, Wang J C, Csorna S E, Danko I, Bonvicini G, Cinabro D, Dubrovin M, McGee S, Bornheim A, Lipeles E, Pappas S P, Shapiro A, Sun W M, Weinstein A J, Briere R A, Chen G P, Ferguson T, Tatishvili G, Vogel H, Watkins M E, Adam N E, Alexander J P, Berkelman K, Boisvert V, Cassel D G, Duboscq J E, Ecklund K M, Ehrlich R, Galik R S, Gibbons L, Gittelman B, Gray S W, Hartill D L, Heltsley B K, Hsu L, Jones C D, Kandaswamy J, Kreinick D L, Magerkurth A, Mahlke-Krüger H, Meyer T O, Mistry N B, Patterson J R, Peterson D, Pivarski J, Richichi S J, Riley D, Sadoff A J, Schwarthoff H, Shepherd M R, Thayer J G, Urner D, Wilksen T, Warburton A, Weinberger M, Athar S B, Avery P, Breva-Newell L, Potlia V, Stoeck H, Yelton J, Benslama K, Cawlfield C, Eisenstein B I, Gollin G D, Karliner I, Lowrey N, Plager C, Sedlack C, Selen M, Thaler J J, Williams J, Edwards K W, Besson D, Anderson S, Frolov V V, Gong D T, Kubota Y, Li S Z, Poling R, Smith A, Stepaniak C J, Urheim J, Metreveli Z, Seth K K, Tomaradze A, Zweber P, Ahmed S, Alam M S, Ernst J, Jian L, Saleem M, Wappler F, Arms K, Eckhart E, Gan K K, Gwon C, Honscheid K, Kagan H, Kass R, Pedlar T K, von Toerne E, Severini H, Skubic P, Dytman S A, Mueller J A, Nam S, Savinov V
Purdue University, West Lafayette, Indiana 47907, USA.
Phys Rev Lett. 2005 May 20;94(19):191801. doi: 10.1103/PhysRevLett.94.191801. Epub 2005 May 17.
Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay lambda(+)(c)lambda--> e(+)nu(e). By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R= f(2)/f(1) = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M(pole) = [2.21 +/- 0.08(stat) +/- 0.14(syst)] GeV/c(2), and the decay asymmetry parameter of the lambda(+)(c), alpha (lambda(c)) = -0.86 +/-0.03(stat) +/- 0.02(syst), for q(2) = 0.67 (GeV/c(2))(2). We compare the angular distributions of the lambda(+)(c) and lambda(-)(c) and find no evidence for CP violation: A(lambda(c)) = (alpha(lambda(c)) + alpha (lambda(c)))/(alpha(lambda(c))-alpha(lambda(c))) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A(lambda), for ppi(-).
利用康奈尔电子储存环上的CLEO探测器，我们研究了衰变过程λ⁺(c)λ⁻→e⁺ν(e)中运动学变量的分布。通过进行四维最大似然拟合，我们确定了形状因子比R = f(2)/f(1) = -0.31 ± 0.05(统计) ± 0.04(系统)，极点质量M(pole) = [2.21 ± 0.08(统计) ± 0.14(系统)] GeV/c²，以及对于q² = 0.67 (GeV/c²)²时λ⁺(c)的衰变不对称参数α(λ(c)) = -0.86 ± 0.03(统计) ± 0.02(系统)。我们比较了λ⁺(c)和λ⁻(c)的角分布，未发现CP破坏的证据：A(λ(c)) = (α(λ(c)) + α(λ⁻(c)))/(α(λ(c)) - α(λ⁻(c))) = 0.00 ± 0.03(统计) ± 0.01(系统) ± 0.02，其中第三个误差来自于π⁻介子的CP破坏参数A(λ)的世界平均值的不确定性。
