πγ→ππ transition and the ρ radiative decay width from lattice QCD

作     者：Constantia Alexandrou Luka Leskovec Stefan Meinel John Negele Srijit Paul Marcus Petschlies Andrew Pochinsky Gumaro Rendon Sergey Syritsyn 

作者机构：Department of Physics University of Cyprus P.O. Box 20537 1678 Nicosia Cyprus Computation-based Science and Technology Research Center Cyprus Institute 20 Kavafi Street 2121 Nicosia Cyprus Department of Physics University of Arizona Tucson Arizona 85721 USA RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973 USA Center for Theoretical Physics Laboratory for Nuclear Science and Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Helmholtz-Institut für Strahlen- und Kernphysik Rheinische Friedrich-Wilhelms-Universität Bonn Nußallee 14-16 D-53115 Bonn Germany Department of Physics and Astronomy Stony Brook University Stony Brook New York 11794 USA 

出 版 物：《Physical Review D》 (Phy. Rev. D)

年 卷 期：2018年第98卷第7期

页      面：074502-074502页

核心收录：

基　　金：National Science Foundation, NSF, (1053575, 1520996) National Science Foundation, NSF Horizon 2020 Framework Programme, H2020, (642069) Horizon 2020 Framework Programme, H2020 

主　　题：Hadron-hadron interactions Leptonic, semileptonic & radiative decays Pions Vector mesons Form factors Lattice QCD 

摘      要：We report a lattice QCD determination of the πγ→ππ transition amplitude for the P-wave, I=1 two-pion final state, as a function of the photon virtuality and ππ invariant mass. The calculation was performed with 2+1 flavors of clover fermions at a pion mass of approximately 320 MeV, on a 323×96 lattice with L≈3.6 fm. We construct the necessary correlation functions using a combination of smeared forward, sequential and stochastic propagators, and determine the finite-volume matrix elements for all ππ momenta up to |P→|=32πL and all associated irreducible representations. In the mapping of the finite-volume to infinite-volume matrix elements using the Lellouch-Lüscher factor, we consider two different parametrizations of the ππ scattering phase shift. We fit the q2 and s dependence of the infinite-volume transition amplitude in a model-independent way using series expansions, and compare multiple different truncations of this series. Through analytic continuation to the ρ resonance pole, we also determine the πγ→ρ resonant transition form factor and the ρ meson photocoupling, and obtain |Gρπγ|=0.0802(32)(20).