Volume 396 - The 38th International Symposium on Lattice Field Theory (LATTICE2021) - Oral presentation
Non-Perturbative Bounds for Semileptonic Decays in Lattice QCD
M. Di Carlo, G. Martinelli, M. Naviglio*, F. Sanfilippo, S. Simula and L. Vittorio
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Pre-published on: May 16, 2022
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Abstract
We present a new method aiming at a non-perturbative, model-independent determination of the momentum dependence of the form factors entering semileptonic decays using unitarity and analyticity constraints. We extend the original proposal and, using suitable two-point functions computed non-perturbatively, we determine the form factors at low-momentum transfer $q^2$ from those computed explicitly on the lattice at large $q^2$, without making any assumption about their $q^2$ dependence. As a training ground we apply the new method to the analysis of the lattice data of the semileptonic $D \rightarrow K \ell \nu_{\ell}$ decays obtained both at finite values of the lattice spacing and at the physical pion point in the continuum limit. We show that, starting from a limited set of data at large $q^2$, it is possible to determine quite precisely the form factors in a model independent way in the full kinematical range, obtaining a remarkable agreement with the direct calculation of the form factors. This finding opens the possibility to obtain non-perturbatively the form factors entering the semileptonic B decays in the full kinematical range.
DOI: https://doi.org/10.22323/1.396.0376
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