Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

Abstract

In a recent paper we studied the effect of new-physics operators with different Lorentz structures on the semileptonic Λ b → Λ c τν τ decay. This decay is of interest in light of the R(D ( * ) ) puzzle in the semileptonicB → D ( * ) τν τ decays. In this work we add tensor operators to extend our previous results and consider both model-independent new physics (NP) and specific classes of models proposed to address the R(D ( * ) ) puzzle. We show that a measurement of R(can strongly constrain the NP parameters of models discussed for the R(D ( * ) ) puzzle. We use form factors from lattice QCD to calculate all Λ b → Λ c τν τ observables. The Λ b → Λ c tensor form factors had not previously been determined in lattice QCD, and we present new lattice results for these form factors here.

Y and ψ leptonic decays as probes of solutions to the R(D (*)) puzzle

“…Consequently, a variety of processes, in addition to B → D ( * ) τ ν, are affected. Some of these, such as t → cτ + τ − decay, B c → τ ν decay [24,41], Λ b → Λ c τν τ decay [51,59], and bb /cc → τ + τ − scattering [47], have been previously studied in the literature, and probe the proposed models. Here, we suggest another class of observables: lepton non-universality in leptonic decays of the Υ and ψ vector-mesons, parameterized by the ratio R V τ / ≡ Γ(V → τ τ )/Γ(V → ).…”

Phenomenology of Ξb→Ξcτν decays

“…We follow Refs. [21,27,28] and write the differential angular distribution for the three-body B 1 → B 2 lν decays in the presence of NP as…”

Implication of RD(*) anomalies on semileptonic decays of Σb and Rajeev1, Dutta2, Kumbhakar3 2019Phys. Rev. D15080View full textAdd to dashboardCite

“…SM predictions World averages Deviation RD = B(B → Dτ ν)/B(B → Dlν) 0.299 ± 0.003 [4][5][6][7] 0.340 ± 0.027 ± 0.013 [13][14][15][16] 1.4σ RD * = B(B → D * τ ν)/B(B → D * lν) 0.258 ± 0.005 [8][9][10][11] 0.295 ± 0.011 ± 0.008 [13][14][15][16][17][18][19][20][21][22] 2.5σ The clear disagreements between the SM predictions and the experimental measurements strongly indicate towards possible new physics. Several new physics scenarios are being investigated within model dependent and model independent frameworks [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Similarly, implications of R D ( * ) anomalies on similar decay modes have been studied as well.…”