2019/08/27 by de Divitiis, G. M., Desiderio, A., Di Carlo, M. +11
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.1908.10160
We present a non-perturbative calculation of the form factors which contribute to the amplitudes for the radiative decays P→ ℓ ν_ℓ γ, where P is a pseudoscalar meson and ℓ is a charged lepton. Together with the non-perturbative determination of the virtual photon corrections to the processes P→ ℓ ν_ℓ, this will allow accurate predictions to be made at O(αem) for leptonic decay rates for pseudoscalar mesons ranging from the pion to the B meson. We are able to separate unambiguously the point-like contribution, the square of which leads to the infrared divergence in the decay rate, from the structure dependent, infrared-safe, terms in the amplitude. The fully non-perturbative, O(a) improved calculation of the inclusive leptonic decay rates will lead to significantly improved precision in the determination of the corresponding Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. Precise predictions for the emission of a hard photon are also very interesting, especially for the decays of heavy D and B mesons for which currently only model-dependent predictions are available to compare with existing experimental data.