BB Potentials in Quenched Lattice QCD

TL;DR

This study computes B-meson potentials in quenched lattice QCD, revealing spin-isospin dependent interactions, and extracts the BB* coupling, providing insights into heavy-meson interactions and quenching effects.

Contribution

It presents the first detailed lattice QCD calculation of B-meson potentials in various spin-isospin channels, including the extraction of the BB* coupling and analysis of quenching artifacts.

Findings

Non-zero central potentials observed in all channels.

Repulsion at short distances in certain channels, attraction in others.

BB* coupling consistent with previous quenched calculations.

Abstract

The potentials between two B-mesons are computed in the heavy-quark limit using quenched lattice QCD at $m_\pi\sim 400~{\rm MeV}$. Non-zero central potentials are clearly evident in all four spin-isospin channels, (I,s_l) = (0,0) , (0,1) , (1,0) , (1,1), where s_l is the total spin of the light degrees of freedom. At short distance, we find repulsion in the $I\ne s_l$ channels and attraction in the I=s_l channels. Linear combinations of these potentials that have well-defined spin and isospin in the t-channel are found, in three of the four cases, to have substantially smaller uncertainties than the potentials defined with the s-channel (I,s_l), and allow quenching artifacts from single hairpin exchange to be isolated. The BB*\pi coupling extracted from the long-distance behavior of the finite-volume t-channel potential is found to be consistent with quenched calculations of the matrix element of the isovector axial-current. The tensor potentials in both of the s_l = 1 channels are found to be consistent with zero within calculational uncertainties.