Weak Decays of Doubly Heavy Baryons: the $1/2\to 1/2$ case

Abstract

Very recently, the LHCb collaboration has observed in the final state $\hat{I}{›}_c^{+}{K}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+}$ a resonant structure that is identified as the doubly-charmed baryon $\hat{I}{ž}_{cc}^{++}$. Inspired by this observation, we investigate the weak decays of doubly heavy baryons $\hat{I}{ž}_{cc}^{++}$, $\hat{I}{ž}_{cc}^{+}$, $\hat{I}{\text{c◯}}_{cc}^{+}$, $\hat{I}{ž}_{bc}^{(\prime )+}$, $\hat{I}{ž}_{bc}^{(\prime )0}$, $\hat{I}{\text{c◯}}_{bc}^{(\prime )0}$, $\hat{I}{ž}_{bb}^0$, $\hat{I}{ž}_{bb}^{-}$ and $\hat{I}{\text{c◯}}_{bb}^{-}$ and focus on the decays into spin $1/2$ baryons in this paper. At the quark level these decay processes are induced by the $c\to d/s$ or $b\to u/c$ transitions, and the two spectator quarks can be viewed as a scalar or axial vector diquark. We first derive the hadronic form factors for these transitions in the light-front approach and then apply them to predict the partial widths for the semi-leptonic and non-leptonic decays of doubly heavy baryons. We find that a number of decay channels are sizable and can be examined in future measurements at experimental facilities like LHC, Belle II and CEPC.

40 pages, 4 figures, to appear in EPJC