Physical observables in the decay Λb → Λc(→ Λ + π) + τ− + ν̄τ

Abstract

We analyze the tauonic semileptonic baryon decays Λ 0 b → Λ + c + τ − +ντ with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization components of the Λ

Polarization in (quasi-)two-body decays and new physics

“…-the decay amplitudes are themselves rotationally invariant. The non-covariant helicity amplitudes were connected in the past years to LI form factors both for semi-leptonic and non-leptonic two-body decays of the type (2) [55][56][57][58][59], with the aim of introducing some models, based on some significant Feynman diagrams. Here we propose a slightly different version of such a treatment, which leads to some results, to be used in the successive sections.…”

Searching for New Physics in the Differential Decay Width of a Lambda_b Semi-leptonic Decay

“…Therefore, more and definitive confirmations of new physics (NP) are searched for in semi-leptonic decays of heavy baryons, like Ω b , Σ b [5] and Λ b , that involve the basic process b → c τ ντ [6][7][8][9][10][11][12][13][14][15]. In particular, a test of lepton flavor universality has been performed by LHCb [16] on the Λ b decay to Λ c ℓν ℓ .…”

Searching for new physics in semi-leptonic baryon decays

“…However, such discrepancies are not definitive, owing to the experimental and theoretical errors, the latter ones being related to the transition form factors, which are affected by serious uncertainties [12,13]. Therefore it is necessary to get confirmations from other channels whose basic processes are the same as in the above mentioned B decays, in particular, from Λ b decays to Λ + − [13,14] and to Λ c −ν [15,16,17,18]. Indeed, the baryonic form factors may pose less difficulties than the corresponding mesonic ones [13], in any case they are calculated to an increasing precision [17,19,20].…”