We present a nonperturbative lattice calculation of the form factors which contribute to the amplitudes for the radiative decays P→ℓν¯ℓγ, where P is a pseudoscalar meson and ℓ is a charged lepton. Together with the nonperturbative determination of the corrections to the processes P→ℓν¯ℓ due to the exchange of a virtual photon, this allows accurate predictions at O(αem) to be made for leptonic decay rates for pseudoscalar mesons ranging from the pion to the Ds meson. We are able to separate unambiguously and nonpertubatively the pointlike contribution, from the structure-dependent, infrared-safe, terms in the amplitude. The fully nonperturbative O(a) improved calculation of the inclusive leptonic decay rates will lead to the determination of the corresponding Cabibbo-Kobayashi-Maskawa matrix elements also at O(αem). Prospects for a precise evaluation of leptonic decay rates with 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.
|Tidsskrift||Physical Review D|
|Status||Udgivet - jan. 2021|
Bibliografisk noteFunding Information:
We gratefully acknowledge helpful discussions with M. Testa. We acknowledge PRACE for awarding us access to Marconi at CINECA, Italy under the Grant No. Pra17-4394. We also acknowledge use of CPU time provided by CINECA under the specific initiative INFN-LQCD123. V. L., G. M., and S. S. thank MIUR (Italy) for partial support under the contract PRIN 2015. The work of C. T. S. was partially supported by STFC (UK) Grant No. ST/P000711/1 and by an Emeritus Fellowship from the Leverhulme Trust. N. T. and R. F. acknowledge the University of Rome Tor Vergata for the support granted to the project PLNUGAMMA. The work of F. S. and S. S. was supported by the Italian Ministry of Research (MIUR) under Grant No. PRIN 20172LNEEZ. The work of F. S. was supported by INFN under GRANT73/CALAT.
© 2021 authors.
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