B_((s))→D^(∗∗)_((s))form factors in HQEFT and model independent analysis of relevant semileptonic decays with NP effects

The form factors of B(s)decays into P-wave excited charmed mesons(including D∗0(2300),D1(2430),D1(2420),D∗2(2460)and their strange counterparts,denoted generically as D∗∗(s))are systematically calculated via QCD sum rules in the framework of heavy quark effective field theory(HQEFT).We consider contributions up to the next leading order of heavy quark expansion and give all the relevant form factors,including the scalar and tensor ones only relevant for possible new physics effects.The expressions for the form factors in terms of several universal wave functions are derived via heavy quark expansion.These universal functions can be evaluated through QCD sum rules.Then,the numerical results of the form factors are presented.With the form factors given here,a model independent analysis of relevant semileptonic decays B(s)→D∗∗(s)lν¯l is performed,including the contributions from possible new physics effects.Our predictions for the differential decay widths,branching fractions,and ratios of branching fractions R(D∗∗(s))may be tested in more precise experiments in the future.

Study of semileptonic decays B_s →D_(s1)(2536)l and B_s →D_(s2)(2573)l in the CQM model

Based on the assumption that Ds1（2536） and Ds2（2573） belong to T doublet （1^＋,2^＋）, we calculate the semileptonic decays of Bs to Ds1（2536） and Ds2（2573） in terms of the Constituent Quark Meson （CQM） model. For Bs → Ds1 （2536）＋ lv^- and B→ → Ds2 （2573）＋lv^-, the order of magnitude of the obtained branching ratios is 10^-3. Our numerical results of the semileptonic decays of Bs to Ds1（2536） and Ds2（2573） are large, which implies that two semileptonic decays should be seen in future experiments.

Role of hyperfine mixing in b→c semileptonic decays of doubly-heavy baryons

We analyze the effects of hyperfine mixing in b → c semileptonic decays of doubly heavy baryons.We qualitatively confirm the results by W.Roberts and M.Pervin in Int.J.Mod.Phys.A,2009,24： 2401– 2413,finding that mixing has a great impact on those transitions.However,predictions without mixing differ by a factor of 2 and this discrepancy translates to the mixed case where large differences in decay widths are observed between the two calculations.

Semileptonic decays B_c →(η_c , J/Ψ)lν in the perturbative QCD approachSemileptonic decays Bc →(ηc , J/Ψ)lν in the perturbative QCD approach

In this paper we study the semileptonic decays of Bc→（ηc, J/ψ）1-v1. We first evaluate the Bc→（ηc, J/ψ） transition form factors Fo（q2）, F＋（q2）, V（q2） and Ao,l,2（q2） by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that： （a） the pQCD predictions for the values of the Bc→ηc, and Bc→J/ψ transition form factors agree well with those obtained by using other methods; （b） the pQCD predictions for the branching ratios of the considered decays are Br（B---qe-e（-））= （4.41_1.09）＋1＂22 10-3 Br（B----rl-） ---- （1.37_＋：337） x 10-3, Br（B：--J/kOe-e（li-,））=（iO.03＋：3）〉lO-3, and Br（B：--＊J/＇r-]T）----（2.92_0.34）10＋40 -3., and （c） we also define and calculate two ratios of the branching ratios Rn and Rj/v, which will be tested by LHCb and the forthcoming Super-B experiments.

Study of singlet-triplet mixing via semileptonic decays

The singlet-triplet mixing of 1P1-3P1 is studied via calculating the branching ratios of semileptonic decay Bs→Ds1lν and B→D1lν by means of the instantaneous Bethe-Salpeter method. Special attention is paid to the relativistic corrections, since they are large for the P-wave states. Using the Mandelstam Formalism, we compute the transition form factors not only in the high-energy lepton end-point region but also in the full Q2 region. And the non-perturbative QCD effects are taken care of in the overlapping integral over the relativistic wave functions of the initial and nial states.

Study of semileptonic decay of Bs^-0→φI^+I^- in QCD sum rule

In this work we study the semileptonic decay of Bs^-0→φI^+I^-(l=e,μ,τ) with the QCD sum rule method. We calculate the Bs^-0→φ ftranslation form factors relevant to this semileptonic decay, then the branching ratios of Bs^-0→φI^+I^-(l=e,μ,τ)decays are calculated with the form factors obtained here. Our result for the branching ratio of Bs^-0→φμ^+μ^- agree very well with the recent experimental data. For the unmeasured decay modes such as Bs^-0→φe^+e^- and Bs^-0→τ^+τ……-, we give theoretical predictions.

Static properties and semileptonic transitions of lowest-lying doubleheavy baryons

The static properties and semileptonic decays of ground-state doubly heavy baryons are studied in the framework of a non-relativistic quark model.Using a phenomenological potential model,we calculate the ground-state masses and magnetic moments of doubly heavy Ω and Ξ baryons.In the heavy quark limit,we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive b→c semileptonic decay widths and branching fractions for 1/2→1/2 baryon transitions.Our obtained results are in agreement with other theoretical predictions.

Isgur-Wise function in Bc decays to charmonium with the Bethe-Salpeter method

The heavy quark effective theory vastly reduces the weak-decay form factors of hadrons containing one heavy quark. Many works attempt to directly apply this theory to hadrons with multiple heavy quarks. In this paper,we examine this confusing application by the instantaneous Bethe-Salpeter method from a phenomenological perspective, and give the numerical results for Bc decays to charmonium where the final states include 1S, 1P, 2S, and 2P. Our results indicate that the form factors parameterized by a single Isgur-Wise function deviate substantially from the full ones, especially when excited states are involved. The relativistic corrections(1/mQcorrections) require the introduction of more non-perturbative universal functions, similar to the Isgur-Wise function, which are the overlapping integrals of the wave functions with the relative momentum between the quark and antiquark.

Revisiting D-mesontwist-2,3 distribution amplitudes

Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this decay may be evidence of new physics beyond the SM.Usually,the D-meson twist-2,3 distribution amplitudes(DAs)Φ2;D(x,μ),d3:D(x,μ),and$g:D(x,μ)are the main error sources when perturbative QCD factorization and light-cone QCD sum rules are used to study B→Dtve.Therefore,it is important to obtain more reasonable and accurate behaviors for these DAs.Motivated by our previous work[Phys.Rev.D 104,no.1,016021(2021)]on pionic leading-twist DA,we revisit D-meson twist-2,3 DAsΦ2:D(x,μ),Φp3:D(x,μ),andΦσ3:D(x,μ).New sum rule formulae for the-moments of these three DAs are suggested for obtaining more accurate values.The light-cone harmonic oscillator models for the DAs are improved,and their parameters are determined by fitting the values of-moments via the least squares method.

Corrections to R_D and R_(D~*) in the BLMSSM

The deviation of the measurement of RD （RD＊） from the Standard Model （SM） expectation is 2.3σ （3.1σ）. RD （RD＊） is the ratio of the branching fraction of ^-B→Dτ^-υτ （^-B→D^＊τ^-υτ ） to that of ^-B→Dl^-υι （^-B→Dl^-υι）, where l=e or μ. This anomaly may imply the existence of new physics （NP）. In this paper, we restudy this problem in the supersymmetric extension of the Standard Model with local gauged baryon and lepton numbers （BLMSSM）, and give one-loop corrections to RD （RD^＊）.

D→P(π,K)helicity form factors within light-cone sum rule approach

In this study,D→P(π,K) helicity form factors(HFFs) are investigated by applying the QCD light-cone sum rule(LCSR) approach.The calculation accuracy is up to the next-to-leading order(NLO) gluon radiation correction of twist-(2,3) distribution amplitude.The resultant HFFs at a large recoil point are Pt,0π(0)=0.688-0.024+0.020 and Pt,0K(O)=0.780-0.029+0.024,in which the contributions from the three particles of the leading order(LO) are so small that they can be safely neglected.The maximal contribution of the NLO gluon radiation correction for Pt,0r,K(0) is less than3%.After extrapolating the LCSR predictions for these HFFs to the whole q2-region,we obtain the decay widths for semileptonic decay processes D→Plvl,which are consistent with the BES-Ⅲ collaboration predictions within error limits.After considering the D+/D0-meson lifetime,we give the branching fractions of D→Plvl with l=e,μ;our predictions also agree with the BES-Ⅲ collaboration results within error limits,especially for the D→πlvl decay process.Finally,we present the forward-backward asymmetry AFBl(q2) and lepton convexity parameter CFl(q2),and further calculate the mean value of these two observations,<AFBl> and {CFl),which may provide a way to test those HFFs in future experiments.