A comprehensive study on the semileptonic decay of heavy flavor mesons

Abstract

The semileptonic decay of heavy flavor mesons offers a clean environment for extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, which describes the CP-violating and flavor changing process in the Standard Model. The involved form factors where the dynamical information is encoded play an essential role in achieving any conclusive statement. That is, the knowledge of the form factors should be under good control, requiring one to examine more observables in addition to the branching fraction. In this paper, we provide the mean value and the q2-dependent shape for further observables [differential decay distribution (dΓ/dq2), forward-backward asymmetry $$ \left({\mathcal{A}}_{FB}^{ls}\right) $$ A FB ls , longitudinal $$ \left({P}_L^l\right) $$ P L l and transverse $$ \left({P}_T^l\right) $$ P T l polarization of a charged lepton, longitudinal polarization of a vector meson in the final state $$ \left({F}_L^l(V)\right) $$ F L l V , leptonic convexity parameter $$ \left({C}_F^l\right) $$ C F l , and trigonometric moments $$ \left({W}_i^l\right) $$ W i l in the decay of D(s) and B(s) to P/Vl+νl (l = e, μ or τ)], based on the predictions of the relevant form factors from the covariant light-front quark model. P and V denote the pseudoscalar and vector meson, respectively. As a comparison, we find a good agreement with the results from the covariant confining quark model and the relativistic quark model in the literature. As it has been observed that the $$ {P}_L^l $$ P L l and $$ {F}_L^l(V) $$ F L l V are crucial quantities to discriminate various New Physics models, the reexamination of these observables from a different method is also essential and necessary.

Semileptonic $B_c \to η_c, J/ψ$ transitions

“…( 5) -( 8) evaluated with empirical lepton and meson masses and our predictions in Figs. 4, we obtain the B c → J/ψ branching fractions reported in Table 5B. Our results accord well with other contemporary estimates.…”

“…Our B c → J/ψ transition form factors are depicted in Figs. 4. Comparing with lQCD results [10], despite minor qualitative differences, most notably concerning V B c →J/ψ (t) in Fig.…”

A closer look at observables from exclusive semileptonic B → (π, ρ)ℓνℓ decays

“…However, the decay modes B → πτ ν τ and B → ρτ ν τ could be sensitive to new fundamental interactions beyond the SM (BSM) due to a relatively large mass of τ . As a reference one could look at some eralier studies on these channels [5][6][7][8][9]. On a similar note the observables associated with the purely leptonic decay B → τ ν τ could also be sensitive to new interactions.…”

New physics and the tau polarization vector in b → $$ \mathrm{c}\tau {\overline{\nu}}_{\tau } $$ decays

“…Certain CM angular averages of these components, 3 also addressed in this work, and that might be experimentally accessed through measurements of subsequent hadronic τ -2 ForB meson semileptonic decays, the dependence on the CM variable cos θτ should be also deduced from the partial wave expansion of the leptonic amplitude within the helicity formalism [64,68,69]. 3 We refer to observables additional to the CM longitudinal τ -polarization asymmetry, A λτ , which is often presented in the literature.…”