Branching Ratios, Forward-backward Asymmetry and Angular Distributions of $B\to K_1l^+l^-$ Decays

Abstract

Using the B → K1 form factors evaluated in the perturbative QCD approach, we study semileptonic B → K1(1270)l + l − and B → K1(1400)l + l − decays, where K1(1270) and K1(1400) are mixtures of K1A and K1B which are 3 P1 and 1 P1 states, respectively. Using the technique of helicity amplitudes, we express the decay amplitudes in terms of several independent and Lorentz invariant pieces. We study the dilepton invariant mass distributions, branching ratios, polarizations and forward-backward asymmetries of B → K1l + l − decays. The ambiguity in the sign of the mixing angle will induce very large differences to branching ratios of semileptonic B decays: branching ratios without resonant contributions either have the order of 10 −6 or 10 −8 . But the polarizations and the forward-backward asymmetries are not sensitive to the mixing angles. We find that the resonant contributions will dramatically change the dilepton invariant mass distributions in the resonant region. We also provide the angular distributions of B → K1l + l − → (Kππ)l + l − decays.

Vertex renormalization and hard scattering symmetry breaking corrections to B to axial vector meson form factors at large recoil

“…Therefore, we can assign different combination of possible helicities and they are summarized in Appendix B. The decay amplitude in term of the lepton and hadron helicity amplitudes can be written as [30] M…”

Strange Axial-vector Mesons in D Meson Decays

“…The difference between the production rates of K 1 (1270) and K 1 (1400) may provide the indication on the value of θ K 1 . It has been widely studied in B-meson decays, such as hadronic decays of B → K 1 (1270), K 1 (1400)P (V ) [29][30][31][32][33][34][35][36][37][38], with P = π, K, η (′) , and V = ρ, ω, K * , φ, J/Ψ, semi-leptonic decays of B → K 1 (1270), K 1 (1400)ℓ + ℓ − [39][40][41][42][43], and radiative decays of B → K 1 (1270), K 1 (1400)γ [21,[44][45][46]. The two-body hadronic D-meson decays with an axial-vector meson in the final states have been studied in [47][48][49][50][51][52][53][54].…”

Pure annihilation type decays in the family non-universal Z′ model

“…The flavor changing neutral currents (FCNC) b → sℓ + ℓ − (ℓ = e, µ, τ), forbidden in the standard model (SM) at the tree level, are very sensitive to the flavor structure of the SM and to the new physics (NP) beyond the SM. The rare decays B → K 1 ℓ + ℓ − involving axial-vector strange mesons, also induced by b → sℓ + ℓ − , have been the subjects of many theoretical studies in the frame work of the SM [1][2][3][4] and some NP models, such as universal extra dimension [5], models involving supersymmetry [6] and the fourth-generation fermions [7]. Generally, these semileptonic decays provide us with a wealth of information with a number of physical observables, such as branching ratio, dilepton invariant mass spectrum, the forward backward asymmetry, lepton polarization asymmetry and other distributions of interest, which play important roles in testing SM and are regarded as probes of possible NP models.…”