Measurement of the absolute branching fraction for $Λ^+_{c}\to Λe^+ν_e$

BESIII Collaboration; M. Ablikim; M. N. Achasov; X. C. Ai; O. Albayrak; M. Albrecht; D. J. Ambrose; A. Amoroso; F. F. An; Q. An; J. Z. Bai; R. Baldini Ferroli; Y. Ban; D. W. Bennett; J. V. Bennett; M. Bertani; D. Bettoni; J. M. Bian; F. Bianchi; E. Boger; I. Boyko; R. A. Briere; H. Cai; X. Cai; O. Cakir; A. Calcaterra; G. F. Cao; S. A. Cetin; J. F. Chang; G. Chelkov; G. Chen; H. S. Chen; H. Y. Chen; J. C. Chen; M. L. Chen; S. J. Chen; X. Chen; X. R. Chen; Y. B. Chen; H. P. Cheng; X. K. Chu; G. Cibinetto; H. L. Dai; J. P. Dai; A. Dbeyssi; D. Dedovich; Z. Y. Deng; A. Denig; I. Denysenko; M. Destefanis; F. De Mori; Y. Ding; C. Dong; J. Dong; L. Y. Dong; M. Y. Dong; S. X. Du; P. F. Duan; E. E. Eren; J. Z. Fan; J. Fang; S. S. Fang; X. Fang; Y. Fang; L. Fava; F. Feldbauer; G. Felici; C. Q. Feng

doi:10.1103/physrevlett.115.221805

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arXiv · 1510.02610

Measurement of the absolute branching fraction for $Λ^+_{c}\to Λe^+ν_e$

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Abstract

We report the first absolute measurement of the branching fraction of $Λ^+_{c}\rightarrow Λe^+ν_e$. This measurement is based on 567 pb$^{-1}$ of $e^+e^-$ annihilation data produced at $\sqrt{s}=4.599$ GeV, which is just above the $Λ^+_c\barΛ^-_c$ threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be $\mathcal B({Λ^+_c\rightarrow Λe^+ν_e})=(3.63\pm0.38({\rm stat})\pm0.20({\rm syst}))\%$, representing a more than twofold improvement in precision upon previously published results. As the branching fraction for $Λ^+_{c}\rightarrow Λe^+ν_e$ is the benchmark for those of other $Λ^+_c$ semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, X. C. Ai, O. Albayrak, M. Albrecht, D. J. Ambrose, A. Amoroso, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, D. W. Bennett, J. V. Bennett, M. Bertani, D. Bettoni, J. M. Bian, F. Bianchi, E. Boger, I. Boyko, R. A. Briere, H. Cai, X. Cai, O. Cakir, A. Calcaterra, G. F. Cao, S. A. Cetin, J. F. Chang, G. Chelkov, G. Chen, H. S. Chen, H. Y. Chen, J. C. Chen, M. L. Chen, S. J. Chen, X. Chen, X. R. Chen, Y. B. Chen, H. P. Cheng, X. K. Chu, G. Cibinetto, H. L. Dai, J. P. Dai, A. Dbeyssi, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, C. Dong, J. Dong, L. Y. Dong, M. Y. Dong, S. X. Du, P. F. Duan, E. E. Eren, J. Z. Fan, J. Fang, S. S. Fang, X. Fang, Y. Fang, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng. 2015-10-09. Measurement of the absolute branching fraction for $Λ^+_{c}\to Λe^+ν_e$. https://doi.org/10.1103/physrevlett.115.221805

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