Inclusive semileptonic Λb decays in the Standard Model and beyond

Abstract

Inclusive semileptonic decays of beauty baryons are studied using the heavy quark expansion to $$ \mathcal{O}\left(1/{m}_b^3\right) $$ O 1 / m b 3 , at leading order in αs. The case of a polarized decaying baryon is examined, with reference to Λb. An extension of the Standard Model effective Hamiltonian inducing b → $$ U\mathrm{\ell}{\overline{\nu}}_{\mathrm{\ell}} $$ U ℓ ν ¯ ℓ transitions (U = u, c and ℓ = e, μ, τ) is considered, which comprises the full set of D=6 semileptonic operators with left-handed neutrinos. The effects of the new operators in several observables are described.

Probing New Physics with heavy hadron decays

“…We collect in this Section some results obtained for observables in Λ → , ℓ − ¯ ℓ . We refer to [2] for the input parameters. For the couplings ℓ , , , , in (1), for = we use the ranges fixed in [31].…”

“…In the case of baryons the dependence on the spin in ( 7) must be kept. In [2] M 1 ... have been derived at order 1/ 3 for a polarized baryon, considering all operators in (1). This extends previous results in [9,11,[21][22][23].…”

“…The index runs over the contribution of the various operators and of their interferences. The coefficients ( ) depend on the NP couplings in (1) and can be found in [2].…”

Comparison of lattice QCD results for inclusive semi-leptonic decays of $B$ mesons with the OPE

“…which can be expanded into a series of local operators, resulting in an expansion in powers of Λ QCD /𝑚 𝑏 , with corrections starting at O Λ QCD /𝑚 𝑏 2 [4]. The structure functions 𝑊 𝑖 are computed in the OPE up to O Λ QCD /𝑚 𝑏 3 and can be found for example in [10].…”

Probing New Physics with heavy hadron decays

“…The observed deviations call for new investigations, in particular focused on other heavy hadron decay processes. Here, we analyze the inclusive semileptonic beauty baryon decays [2], for which the nonperturbative effects of strong interactions can be systematically treated exploiting an expansion in the inverse heavy quark mass [3,4].…”