Efficient lattice QCD computation of radiative-leptonic-decay form factors at multiple positive and negative photon virtualities

Abstract

In previous work Phys. Rev. D 107, 074507 (2023), we showed that form factors for radiative leptonic decays of pseudoscalar mesons can be determined efficiently and with high precision from lattice QCD using the ``3d method,'' in which three-point functions are computed for all values of the current-insertion time and the time integral is performed at the data-analysis stage. Here, we demonstrate another benefit of the 3d method: the form factors can be extracted for any number of nonzero photon virtualites from the same three-point functions at no extra cost. We present results for the $D_s\to \ell \nu {\gamma }^{\ast }$ vector form factor as a function of photon energy and photon virtuality, for both positive and negative virtuality. In our analysis, we separately consider the two different time orderings and the different quark flavors in the electromagnetic current. We discuss in detail the behavior of the unwanted exponentials contributing to the three-point functions, as well as the choice of fit models and fit ranges used to remove them for various values of the virtuality. While positive photon virtuality is relevant for decays to multiple charged leptons, negative photon virtuality suppresses soft contributions and is of interest in QCD-factorization studies of the form factors.

21 pages, 12 figures, version accepted to Physical Review D

References in corpus (13)

• Continuum Limit Physics from 2+1 Flavor Domain Wall QCD
• Form Factors in the radiative pion decay
• On the extraction of spectral densities from lattice correlators
• On the Radiative Pion Decay
• Comparison of lattice QCD+QED predictions for radiative leptonic decays of light mesons with experimental data
• QCD factorization of the four-lepton decay $B^{-}\to \ell {\bar{\nu }}_{\ell }{\ell }^{(\prime )}{\bar{\ell }}^{(\prime )}$
• Insights on the current semi-leptonic $B$-decay discrepancies -- and how $B_s\to {\mu }^{+}{\mu }^{-}\gamma$ can help
• Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD
• Lattice QCD calculation of $K\to \ell {\nu }_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$ decay width
• Searching new physics in rare $B$-meson decays into multiple muons
• Virtual Photon Emission in Leptonic Decays of Charged Pseudoscalar Mesons
• Dispersion relations for $B^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{\prime -}{\ell }^{\prime +}$ form factors
• Kaon radiative leptonic decay rates from lattice QCD simulations at the physical point