Overview of Λc decays

Abstract

The decays of the ground-state charmed baryon Λ c are now close to being completely mapped out. In this paper we discuss some remaining open questions, whose answers can help shed light on weak processes contributing to those decays, calculations of such quantities as transition form factors in lattice QCD, and missing decay modes such as Λ c → Λ Ã l þ ν l , where Λ Ã is an excited resonance. The discussion is in part a counterpart to a previous analysis of inclusive D s decays.

Measurement of the Absolute Branching Fraction of the Inclusive Decay Λc+→Λ+X

“…In addition, our result is 2.4σ larger than the value in Ref. [14], inferred from the known exclusive Λ-involved decay rates in the statistical isospin model. This indicates that there exist some large-rate decay types, which have not yet been observed.…”

“…Furthermore, the sum of the BFs of the known exclusive decay final states involving the Λ in PDG is ð24.5 AE 2.1Þ% [5]. The difference between the inclusive and exclusive rates will point out the size of as yet unknown decays, which requires high precision measurement of BðΛ þ c → Λ þ XÞ [14]. In addition, precise knowledge of BðΛ þ c → Λ þ XÞ provides an essential input for exploring the decays of b-flavored hadrons involving a Λ þ c in the final states.…”

Addendum to “Overview of Λc decays”

“…0.69 AE 0.23 [1] ( pinned down yet, with an S-value of 1.4 [1]. The statistical isospin model is poorly obeyed for the NKπ and Σ3π modes but well obeyed for the Σ2π modes [2], possibly indicating the need to take into account the resonant substructure. Nevertheless, one can draw some general conclusions.…”

“…The decays of the charmed baryon Λ c [1] appear to be within about 10% of fully mapped out [2] when a statistical isospin model [3,4] is used to estimate branching fractions for as-yet-unseen decay modes. In this addendum to Ref.…”

“…In this addendum to Ref. [2] we display graphically the modes which have been seen and those anticipated. Part of the ∼10% shortfall may be composed of decay modes such as Λ c → Λ Ã l þ ν l , where Λ Ã is an excited resonance, or may be due to a shortcoming in the statistical isospin model.…”