QCD corrections to theBcto charmonia semileptonic decays

Abstract

We present a detailed analysis on the Bc meson semi-leptonic decays, Bc → ηc(J/ψ)ℓν, up to next-to-leading order (NLO) QCD correction. We adopt the principle of maximum conformality (PMC) to set the renormalization scales for those decays. After applying the PMC scale setting, we determine the optimal renormalization scales for the Bc → ηc(J/ψ) transition form factors (TFFs). Because of the same β0-terms, the optimal PMC scales at the NLO level are the same for all those TFFs, i.e. µ PMC r ≈ 0.8GeV. We adopt a strong coupling model from the massive perturbation theory (MPT) to achieve a reliable pQCD estimation in this low energy region. Furthermore, we adopt a monopole form as an extrapolation for the Bc → ηc(J/ψ) TFFs to all their allowable q 2 region. Then, we predict Γ Bc→ηcℓν (ℓ = e, µ) = (71.53 +11.27 −8.90 ) × 10 −15 GeV, ΓB c→ηc τ ν = (27.14 +5.93 −4.33 ) × 10 −15 GeV, Γ Bc→J/ψℓν (ℓ = e, µ) = (106.31 +18.59 −14.01 ) × 10 −15 GeV, Γ Bc→J/ψτ ν = (28.25 +6.02 −4.35 ) × 10 −15 GeV, where the uncertainties are squared averages of all the mentioned error sources. We show that the present prediction of the production cross section times branching ratio for B + c → J/ψℓ + v relative to that for B + → J/ψK + , i.e. ℜ(J/ψℓ + ν), is in a better agreement with CDF measurements than the previous predictions.

Revisiting the new-physics interpretation of the b → cτν data

“…For the B c → J/ψ form factors, they have been studied in a variety of approaches [106][107][108][109][110][111][112][113][114][115][116] (for earlier analysis focused on this decay mode see refs. [116][117][118][119]).…”

Relativistic effects in the semileptonic Bc decays to charmonium with the Bethe-Salpeter method

“…The LHCb experiment can produce and reconstruct a large number of the B c meson events, and it provides a solid platform to study the properties of the B c meson precisely. A great deal of work has been done on various B c decays under different approaches, such as NRQCD approach [1,[11][12][13], the perturbative QCD approach (PQCD) [14][15][16][17], the relativistic quark model (RQM) [18][19][20][21], Light-cone sum rules (LCSR) [22], the nonrelativistic constituent quark model (NCQM) [23] and QCD sum rules (QCDSR) [24][25][26][27].…”

Relativistic corrections to light-cone distribution amplitudes of S-wave Bc mesons and heavy quarkonia

“…for the decay constants, and 20) for the LCDAs. Here ∆ = 0 is for NDR scheme [49], and ∆ = 1 for the HV scheme [50].…”

“…Meanwhile the NRQCD factorization has been adopted in refs. [18][19][20][21][22][23][24][25][26], in which the non-perturbative physics reside in a few NRQCD matrix elements. The LHCb collaboration has started comprehensive experimental studies of the decays [27], and some phenomenological studies can be found in refs.…”