Inclusive semileptonic $B$-decays from lattice QCD

TL;DR

This paper demonstrates a lattice QCD approach to calculate inclusive semileptonic B_s-meson decays, validating the method against theoretical predictions and paving the way for precise determination of CKM matrix elements.

Contribution

It introduces a novel lattice QCD method for inclusive decay calculations using spectral densities and kernel reconstruction, validated against operator-product-expansion predictions.

Findings

Lattice results agree with operator-product-expansion predictions.

Method successfully extracts spectral densities from Euclidean correlators.

Paves the way for precise lattice-based CKM element determinations.

Abstract

We present the lattice QCD calculation of inclusive semileptonic $B_s$-meson decays. We follow a recently proposed method, which is based on the extraction of smeared spectral densities from Euclidean correlation functions and on the numerical reconstruction of the integration kernel relevant for the inclusive decay rate calculation. We compute four-point Euclidean correlation functions using JLQCD and ETM gauge ensembles with unphysically light $b$-quark masses, and apply two different methods for the integration kernel reconstruction. Finally, we show that the lattice results obtained in this work are in good agreement with the analytic predictions of the operator-product-expansion. This opens the path for a future full lattice QCD calculation to be used as theoretical input for the determination of the magnitude of the CKM element $V_{cb}$.