Exclusive-Inclusive Ratio of Semileptonic Lambda_b-Decays

Abstract

We present theoretical evidence that the exclusive/inclusive ratio of semileptonic ${\Lambda }_b$-decays exceeds that of semileptonic B-decays where the experimental exclusive/inclusive ratio amounts to about 66%. We start from the observation that the spectator quark model provides a lower bound on the leading order Isgur-Wise function of the ${\Lambda }_b\to {\Lambda }_c$ transition in terms of the corresponding $B\to D,D^{\ast }$ mesonic Isgur-Wise function. Using experimental data for the $B\to D,D^{\ast }$ mesonic Isgur-Wise functions this bound is established. Applying a Bethe-Salpeter model including spectator quark interactions and a QCD sum rule estimate of the ${\Lambda }_b\to {\Lambda }_c$ transition form factor which satisfy the spectator quark model bound we predict the exclusive/inclusive ratio of semileptonic ${\Lambda }_b$ decay rates to lie in a range between 0.81 and 0.92. We also provide an upper bound on the baryonic Isgur-Wise function which is determined from the requirement that the exclusive rate should not exceed the inclusive rate.

RevTeX, 18 pages, 4 figures

References in corpus (3)

• Baryonic currents and their correlators in the Heavy Quark Effective Theory
• Weak decays Xi_Q -> Lambda_Q pi
• Lambda_b and Lambda_c baryon decays at finite values of heavy quark masses

Cited by in corpus (8)

• The semileptonic decay Lambda_b -> Lambda_c + tau(-) + antinu_tau in the covariant confined quark model
• Semileptonic decays of double heavy baryons
• Combined nonrelativistic constituent quark model and heavy quark effective theory study of semileptonic decays of Λ_b and Ξ_b baryons
• Note on the Slope Parameter of the Baryonic Λ_b to Λ_c Isgur-Wise Function
• Choice of heavy baryon currents in QCD sum rules
• Nonleptonic ${\Lambda }_b$ decays to $D_s(2317)$, $D_s(2460)$ and other final states in Factorization
• Exclusive and Inclusive Semileptonic Lambda_b-Decays
• $O({\alpha }_s)$ perturbative and nonperturbative corrections to polarized semileptonic ${\Lambda }_b$ decay distributions