The Spectrum of Meson States in the Isovector Non-strange T⁺_1u Channel by the Stochastic LapH Method in Lattice QCD

<p>A new method of estimating quark propagation, known as Stochastic LapH, has<br>provided a way of computing many observables in lattice QCD which have previously<br>been inaccessible due to computational expense. In this work, the first large-scale<br>applications of the Stochastic LapH method to excited meson spectroscopy are presented.<br>We discuss the construction of single-meson and two-meson operators with<br>LapH smearing, and procedures for selecting and correlating large sets of these operators<br>are described. We then present the analysis of a 56 × 56 correlator matrix<br>of operators in the isovector nonstrange T⁺_1u channel. We extract the energy of the<br>ρ meson, and discuss the identification and energy extractions of excited ρ mesons.<br>Operators are included for all <br>avor combinations that can result in the I = 1, S = 0<br>total quantum numbers of the desired symmetry channel. The correlation matrix is<br>calculated on 551 configurations of an anisotropic 24³×128 gauge field ensemble with<br>clover-improved Wilson fermions. Good signal quality is obtained even for correlators<br>involving same-time quark lines and isoscalar mesons as part of two-meson operators.<br>Results are compared with experimental values compiled by the Particle Data Group.</p>