Radiative decays of heavy-light mesons and the fH, H*, H1(T) decay constants

The on-shell matrix elements, or couplings g HH*(H1)gamma describing the B(D)-> B(D)q gamma and B -> B gamma (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) -> gamma form factors which in turn are connected to QED-corrections in leptonic decays B(D) -> l (nu) over bar. Since the couplings and residues are related by the decay constants f and fH*(H1), we determine them at next-leading order as a by-product. The quantities {fT, fT} have not previously been subjected to a QCD sum rule determination. All results are compared with the existing experimental and theoretical literature.

Automated summary

The on-shell matrix elements and couplings describing radiative decays B(D)->B(D)q gamma and B->B gamma have been determined for the first time using light-cone sum rules at next-to-leading order. Two different interpolating operators were used, providing additional robustness to the results. Agreement was found with experimentally known rates for the D*-meson, and the couplings governing the lowest pole residue in the form factors for B(D) -> gamma were connected to QED-corrections in leptonic decays B(D) -> l (nu) over bar.