ππ P-wave resonant scattering from lattice QCD

¹ Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Kavafi Str., Nicosia, 2121, Cyprus
² Department of Physics, University of Cyprus, POB 20537, 1678 Nicosia, Cyprus
Department of Physics, University of Arizona, Tucson, AZ 85721, USA
⁴ RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973, USA
⁵ Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁶ Department of Mathematics and Natural Sciences, University of Wuppertal, D-42119 Wuppertal, Germany
⁷ Helmholtz-Institut für Strahlen-und Kernphysik, University of Bonn, D-53115 Bonn, Germany
⁸ Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794, USA

^* Speaker, e-mail: s.paul@hpc.leap.eu

Published online: 26 March 2018

Abstract

We present a high-statistics analysis of the ρ resonance in ππ scattering, using 2 + 1 flavors of clover fermions at a pion mass of approximately 320 MeV and a lattice size of approximately 3:6 fm. The computation of the two-point functions are carried out using combinations of forward, sequential, and stochastic propagators. For the extraction of the ρ-resonance parameters, we compare different fit methods and demonstrate their consistency. For the ππ scattering phase shift, we consider different Breit-Wigner parametrizations and also investigate possible nonresonant contributions. We find that the minimal Breit-Wigner model is suffcient to describe our data, and obtain am_ρ = 0:4609(16)_stat(14)_sys and g_ρππ = 5:69(13)_stat(16)_sys. In our comparison with other lattice QCD results, we consider the dimensionless ratios am_ρ/am_N and am_π/am_N to avoid scale setting ambiguities.