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arXiv · 2512.05178

Evidence for the semileptonic decays $Λ_c^{+} \to Σ^{\pm} π^{\mp} e^+ ν_e$

BESIII Collaboration·M. Ablikim·M. N. Achasov·P. Adlarson·X. C. Ai·R. Aliberti·A. Amoroso·Q. An·Y. Bai·O. Bakina·Y. Ban·H. -R. Bao·V. Batozskaya·K. Begzsuren·N. Berger·M. Berlowski·M. Bertani·D. Bettoni·F. Bianchi·E. Bianco·A. Bortone·I. Boyko·R. A. Briere·A. Brueggemann·H. Cai·M. H. Cai·X. Cai·A. Calcaterra·G. F. Cao·N. Cao·S. A. Cetin·X. Y. Chai·J. F. Chang·G. R. Che·Y. Z. Che·G. Chelkov·C. H. Chen·Chao Chen·G. Chen·H. S. Chen·H. Y. Chen·M. L. Chen·S. J. Chen·S. L. Chen·S. M. Chen·T. Chen·X. R. Chen·X. T. Chen·Y. B. Chen·Y. Q. Chen·Z. J. Chen·Z. K. Chen·S. K. Choi·X. Chu·G. Cibinetto·F. Cossio·J. J. Cui·H. L. Dai·J. P. Dai·A. Dbeyssi·R. E. de Boer·D. Dedovich·C. Q. Deng·Z. Y. Deng·A. Denig·I. Denysenko·M. Destefanis·F. De Mori·B. Ding·X. X. Ding·Y. Ding·Y. X. Ding·J. Dong·L. Y. Dong·M. Y. Dong·X. Dong·M. C. Du·S. X. Du·Y. Y. Duan·Z. H. Duan·P. Egorov·G. F. Fan·J. J. Fan·Y. H. Fan·J. Fang·S. S. Fang·W. X. Fang·Y. Q. Fang·R. Farinelli·L. Fava·F. Feldbauer·G. Felici·C. Q. Feng·J. H. Feng·Y. T. Feng·M. Fritsch·C. D. Fu·J. L. Fu·Y. W. Fu·H. Gao
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Abstract

Using $4.5\, fb^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at center-of-mass energies between $4.600$ and $4.699\,GeV$, we search for the semileptonic decays $Λ_c^{+} \to Σ^{+} π^{-} e^+ ν_e$ and $Λ_c^{+} \to Σ^{-} π^{+} e^+ ν_e$ for the first time. Assuming their branching fractions are equal under isospin symmetry, evidence for $Λ_c^{+} \to Σ^{\pm} π^{\mp} e^+ ν_e$ is reported with a significance of $3.6σ$. The corresponding branching fraction is measured to be $\mathcal{B}(Λ_c^{+} \to Σ^\pmπ^\mp e^+ν_e) = (7.7^{+2.5}_{-2.3_{\rm stat.}}\pm1.3_{\rm syst.})\times 10^{-4}$, which is consistent with quark model predictions within two standard deviations.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R. Che, Y. Z. Che, G. Chelkov, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, Z. K. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, Y. Y. Duan, Z. H. Duan, P. Egorov, G. F. Fan, J. J. Fan, Y. H. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, Y. T. Feng, M. Fritsch, C. D. Fu, J. L. Fu, Y. W. Fu, H. Gao. 2025-12-04. Evidence for the semileptonic decays $Λ_c^{+} \to Σ^{\pm} π^{\mp} e^+ ν_e$. https://doi.org/10.1103/xk1n-14dk

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