Abstract
The semileptonic decays of $\Lambda_{b}\to\Lambda_{c}^{(*)}\ell\nu_\ell$ and $\Lambda_{c}\to\Lambda^{(*)}\ell\nu_\ell$ are studied in the light-front quark model in this work. Instead of the quark-diquark approximation, we use the three-body wave functions obtained by baryon spectroscopy. The ground states $(1/2^{+})$, the $\lambda$-mode orbital excited states $(1/2^{-})$, and the first radial excited states $(1/2^{+})$ of $\Lambda_{(c)}^{(*)}$ are considered. The discussions are given for the form factors, partial widths, branching fractions, leptonic forward-backward asymmetries, hadron polarizations, lepton polarizations, and the lepton flavor universalities. Our results are useful for the inputs of heavy baryon decays and understanding the baryon structures, and helpful for experimental measurements.
Highlights
In recent years, a lot of progress has been made in the understanding of weak decays of heavy-flavor baryons, such as the observation of the double-charm baryon Ξþccþ [1,2], the first measurements of the absolute branching fractions of Λþc and Ξþc ;0 decays [3,4,5,6,7,8], and the evidence of CP violation in Λ0b → pπþπ−π− [9]
The simpler dynamics of semileptonic decays compared to the nonleptonic ones, can help us to search for the new physics beyond the Standard Model (SM) and study the structures of excited states of baryons
We present our results for the form factors of Λb → ΛðcÃÞð1=2ÆÞ and Λc → ΛðÃÞð1=2ÆÞ transitions
Summary
A lot of progress has been made in the understanding of weak decays of heavy-flavor baryons, such as the observation of the double-charm baryon Ξþccþ [1,2], the first measurements of the absolute branching fractions of Λþc and Ξþc ;0 decays [3,4,5,6,7,8], and the evidence of CP violation in Λ0b → pπþπ−π− [9]. The BESIII measurements show that the branching fraction of the exclusive process of BðΛþc → ΛeþνeÞ 1⁄4 ð3.63 Æ 0.43Þ% [4] dominates the inclusive decay of BðΛþc → eþXÞ 1⁄4 ð3.95 Æ 0.35Þ% [7], with a fraction of ð91.9 Æ 13.6Þ% It implies a little room for other semileptonic processes involving excited final states. The key issue in the theoretical study of semileptonic decays is to calculate the weak transition form factors. They are the important inputs in the nonleptonic decays, such as in the prediction of the discovery channels of the doubly charmed baryons [15,16,17,18]. The conclusion and discussion are given in the last section
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