Doubly-heavy baryon weak decays: Ξbc0 →pK- and Ξcc+ → Σc++(2520)K-

Doubly-heavy baryons, with two heavy and one light quarks, are expected to exist in QCD and their masses have been predicted in the quark model. However their existence is not well established so far in experiment. In this work, we explore the possibility of searching for Xi(bc) and Xi(+)(cc) ccin the W-exchange processes, Xi(0)(bc) -> pK(-) and Xi(+)(cc) -> Sigma(++)(c) -> (2520) K-. On the basis of perturbative calculations, we estimate the branching ratio of the first decay as BR(Xi(0)(bc)-> p(+) K-) approximate to 3.21 xR(f)(2)xR tau x10(-7), where R-f(R-tau) are the ratios of the decay constants (lifetimes) of Xi(0)(bc) and Lambda(0)(b). The branching ratio of Xi(+)(cc) -> Sigma(++)(c) (2520) K- is related to that of Lambda(+)(c)-> Delta(++) K-, and thereby a conjectured topology analysis leads to the range for the branching ratio as: BR(Xi(+)(cc) -> Sigma(++)(c)(2520) K-) is an element of[0.36%, 1.80%]. The decay Xi(+)(cc) -> Sigma(++)(c) (2520) K- would be reconstructed in the Lambda K-+(c)-pi(+) final state which is easy to access even at a hadron collider. Based on the two facts that abundant heavy quarks can be produced at a hadron collider like LHC, and the branching ratios of Xi(0)(bc)-> pK(-) and Xi(+)(cc) -> Sigma(++)(c) (2520) K- are sizable, we urge our experimental colleagues to perform a search at LHCb. This will presumably lead to the discovery of the Xi(bc) and Xi(+)(cc), and precision measurements of the branching ratios in the future are helpful to investigate their decay mechanism. (C) 2017 The Author(s). Published by Elsevier B.V.