Phys. Rev. Lett.
94,
191801
(2005)
[5 pages]
Improved Measurement of the Form Factors in the Decay Λc+→Λe+νe
J. W. Hinson et al. CLEO Collaboration
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J. W. Hinson1, G. S. Huang1, J. Lee1, D. H. Miller1, V. Pavlunin1, R. Rangarajan1, B. Sanghi1, E. I. Shibata1, I. P. J. Shipsey1, D. Cronin-Hennessy2, C. S. Park2, W. Park2, J. B. Thayer2, E. H. Thorndike2, T. E. Coan3, Y. S. Gao3, F. Liu3, R. Stroynowski3, M. Artuso4, C. Boulahouache4, S. Blusk4, E. Dambasuren4, O. Dorjkhaidav4, R. Mountain4, H. Muramatsu4, R. Nandakumar4, T. Skwarnicki4, S. Stone4, J. C. Wang4, S. E. Csorna5, I. Danko5, G. Bonvicini6, D. Cinabro6, M. Dubrovin6, S. McGee6, A. Bornheim7, E. Lipeles7, S. P. Pappas7, A. Shapiro7, W. M. Sun7, A. J. Weinstein7, R. A. Briere8, G. P. Chen8, T. Ferguson8, G. Tatishvili8, H. Vogel8, M. E. Watkins8, N. E. Adam9, J. P. Alexander9, K. Berkelman9, V. Boisvert9, D. G. Cassel9, J. E. Duboscq9, K. M. Ecklund9, R. Ehrlich9, R. S. Galik9, L. Gibbons9, B. Gittelman9, S. W. Gray9, D. L. Hartill9, B. K. Heltsley9, L. Hsu9, C. D. Jones9, J. Kandaswamy9, D. L. Kreinick9, A. Magerkurth9, H. Mahlke-Krüger9, T. O. Meyer9, N. B. Mistry9, J. R. Patterson9, D. Peterson9, J. Pivarski9, S. J. Richichi9, D. Riley9, A. J. Sadoff9, H. Schwarthoff9, M. R. Shepherd9, J. G. Thayer9, D. Urner9, T. Wilksen9, A. Warburton9, M. Weinberger9, S. B. Athar10, P. Avery10, L. Breva-Newell10, V. Potlia10, H. Stoeck10, J. Yelton10, K. Benslama11, C. Cawlfield11, B. I. Eisenstein11, G. D. Gollin11, I. Karliner11, N. Lowrey11, C. Plager11, C. Sedlack11, M. Selen11, J. J. Thaler11, J. Williams11, K. W. Edwards12, D. Besson13, S. Anderson14, V. V. Frolov14, D. T. Gong14, Y. Kubota14, S. Z. Li14, R. Poling14, A. Smith14, C. J. Stepaniak14, J. Urheim14, Z. Metreveli15, K. K. Seth15, A. Tomaradze15, P. Zweber15, S. Ahmed16, M. S. Alam16, J. Ernst16, L. Jian16, M. Saleem16, F. Wappler16, K. Arms17, E. Eckhart17, K. K. Gan17, C. Gwon17, K. Honscheid17, H. Kagan17, R. Kass17, T. K. Pedlar17, E. von Toerne17, H. Severini18, P. Skubic18, S. A. Dytman19, J. A. Mueller19, S. Nam19, and V. Savinov19 (CLEO Collaboration)
1Purdue University, West Lafayette, Indiana 47907, USA
2University of Rochester, Rochester, New York 14627, USA
3Southern Methodist University, Dallas, Texas 75275, USA
4Syracuse University, Syracuse, New York 13244, USA
5Vanderbilt University, Nashville, Tennessee 37235, USA
6Wayne State University, Detroit, Michigan 48202, USA
7California Institute of Technology, Pasadena, California 91125, USA
8Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
9Cornell University, Ithaca, New York 14853, USA
10University of Florida, Gainesville, Florida 32611, USA
11University of Illinois, Urbana-Champaign, Illinois 61801, USA
12Carleton University, Ottawa, Ontario, Canada K1S 5B6 and the Institute of Particle Physics, Canada
13University of Kansas, Lawrence, Kansas 66045, USA
14University of Minnesota, Minneapolis, Minnesota 55455, USA
15Northwestern University, Evanston, Illinois 60208, USA
16State University of New York at Albany, Albany, New York 12222, USA
17The Ohio State University, Columbus, Ohio 43210, USA
18University of Oklahoma, Norman, Oklahoma 73019, USA
19University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
Received 29 December 2004; published 17 May 2005
Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay Λc+→Λe+νe. By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R=f2/f1=-0.31±0.05(stat)±0.04(syst), the pole mass, Mpole=[2.21±0.08(stat)±0.14(syst)] GeV/c2, and the decay asymmetry parameter of the Λc+, αΛc=-0.86±0.03(stat)±0.02(syst), for ⟨q2⟩=0.67 (GeV/c2)2. We compare the angular distributions of the Λc+ and Λ̅ c- and find no evidence for CP violation: AΛc=(αΛc+αΛ̅ c)/(αΛc-αΛ̅ 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, AΛ, for Λ→pπ-.
© 2005 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.94.191801
DOI:
10.1103/PhysRevLett.94.191801
PACS:
13.30.Ce, 11.30.Er, 14.20.Lq, 14.65.Dw
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