Radiative decays of heavy-light mesons and the $$ {f}_{H,{H}^{\ast },{H}_1}^{(T)} $$ decay constants

Abstract

The on-shell matrix elements, or couplings $$ {g}_{H{H}^{\ast}\left({H}_1\right)\upgamma} $$ g H H ∗ H 1 γ , describing the $$ B{(D)}_q^{\ast } $$ B D q ∗ → B(D)qγ and B1q → Bqγ (q = u, d, s) radiative decays, are determined from light-cone sum rules at next-to-leading order for the first time. Two different interpolating operators are used for the vector meson, providing additional robustness to our results. For the D*-meson, where some rates are experimentally known, agreement is found. The couplings are of additional interest as they govern the lowest pole residue in the B(D) → γ form factors which in turn are connected to QED-corrections in leptonic decays B(D) → ℓ$$ \overline{\nu} $$ ν ¯ . Since the couplings and residues are related by the decay constants $$ {f}_{H^{\ast}\left({H}_1\right)} $$ f H ∗ H 1 and $$ {f}_{H^{\ast}\left({H}_1\right)}^T $$ f H ∗ H 1 T , we determine them at next-leading order as a by-product. The quantities $$ \left\{{f}_{H^{\ast}}^T,{f}_{H_1}^T\right\} $$ f H ∗ T f H 1 T have not previously been subjected to a QCD sum rule determination. All results are compared with the existing experimental and theoretical literature.

The D∗Dπ and B∗Bπ couplings from light-cone sum rules

“…In Ref. [142], the NLO QCD corrections to the short-distance photon emission diagrams in these sum rules have been calculated. In Table 8, we present the two most recent LCSRs predictions.…”

“…Note that, in contrast to Ref. [142], the complete set of photon DAs at the twist-four accuracy [128] was employed in Ref. [141], where one can find a detailed discussion and comparison with other theory predictions.…”

Lepton Flavor Violation and Lepton Flavor Universality Violation in b and c Decays

“…This advantageous property holds specifically for radiative leptonic decays-that is, it does not hold in the semileptonic case. 4 In addition, the B → γ FFs in this q 2 region have been calculated in several recent studies based on QCD factorization and soft collinear effective theory (84) or based on light-cone sum rules (85)(86)(87)(88)(89). The factorization approach ensures that the main parametric dependence of the leading-power FFs in this region is on the B meson light-cone distribution amplitude-hence, the challenge is to control this quantity to a satisfactory accuracy (see approaches in References 90 and 91 and related discussions in References 92 and 93).…”

B Meson Decay Constants Using Relativistic Heavy Quarks

“…The pseudoscalar decay constants of 𝐵 mesons with a light/strange valence quark are well-studied using nonperturbative methods. From QCD sum rules, the best determinations have a precision ∼ 10% [7][8][9]. With lattice QCD, these are currently known to a precision of less than 1% [10][11][12][13][14]; from the pseudoscalar decay constants also comes the important SU(3)-breaking ratio 𝑓 𝐵 𝑠 / 𝑓 𝐵 .…”