String breaking with dynamical Wilson fermions

TL;DR

This paper reports the first observation of string breaking in full 4D lattice QCD with dynamical Wilson fermions, demonstrating the transition from a static quark-antiquark string to a static-light meson-antimeson system.

Contribution

The study introduces a precise method for measuring string breaking in full QCD using dynamical Wilson fermions and advanced computational techniques for matrix elements.

Findings

Clear signature of level-splitting observed

String breaking induced by sea quarks detected

Unprecedented accuracy in matrix element determination

Abstract

We present results of our ongoing determination of string breaking in full QCD with N_f=2 Wilson fermions. Our investigation of the fission of the static quark-antiquark string into a static-light meson-antimeson system is based on dynamical configurations of size 24^3 x 40 produced by the TxL collaboration. Combining various optimization methods we determine the matrix elements of the two-by-two system with so far unprecedented accuracy. The all-to-all light quark propagators occurring in the transition element are computed from eigenmodes of the Hermitian Wilson-Dirac matrix complemented by stochastic estimates in the orthogonal subspace. We observe a clear signature for level-splitting between ground state and excited potential. Thus, for the first time, string breaking induced by sea quarks is observed in a simulation of 4-dimensional lattice-QCD.