We present a lattice determination of the hadronic susceptibilities that, thanks to unitarity and analyticity, constrain the form factors entering the semileptonic b→c transitions. We evaluate the transverse and longitudinal susceptibilities of the vector and axial polarization functions at zero momentum transfer from the moments of appropriate two-point correlation functions. The latter are obtained on the lattice employing gauge ensembles of the Extended Twisted Mass Collaboration (ETMC) with Nf=2+1+1 flavors of Wilson-clover twisted-mass quarks with masses of all the dynamical quark flavors tuned close to their physical values. The simulations are carried out at four values of the lattice spacing, a≃(0.057,0.068,0.080,0.091) fm, with spatial lattice sizes up to L≃7.6 fm. Heavy-quark masses up to ≈3.5 times the physical charm mass are employed, allowing for a smooth extrapolation to the physical b-quark mass.
@article{arxiv.2401.03920,
title = {Hadronic susceptibilities for b to c transitions from two point correlation functions},
author = {Aurora Melis and Francesco Sanfilippo and Silvano Simula},
journal= {arXiv preprint arXiv:2401.03920},
year = {2024}
}