2021/11/29 by Matteo Di Carlo, Di Carlo, Matteo, Guido Martinelli +9
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #hep-ex #hep-lat #hep-ph
paper · pdf · doi:10.48550/arxiv.2111.14424
11 pages, 4 figures. Talk presented at the 38th International Symposium on Lattice Field Theory (Lattice 2021), 26-30 July, 2021, Zoom/Gather@Massachusetts Institute of Technology
arxiv created 2021/11/29 · arxiv updated 2021/11/30
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 q2 from those computed explicitly on the lattice at large q2, without making any assumption about their q2 dependence. As a training ground we apply the new method to the analysis of the lattice data of the semileptonic D → K ℓ νℓ 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 q2, 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.