Lattice QCD determination of the normalization of the leading-twist photon distribution amplitude and susceptibility of the quark condensate
Year: 2024
Type: article
Abstract: The normalization of the leading-twist photon distribution amplitude (DA), f γ ⊥ , is an important ingredient in the study of exclusive processes involving the photon emission by means of QCD sum-rules. In this paper we determine the up-, down- and strange-quark contribution to f γ ⊥ by exploiting its relation to the zero-momentum two-point correlation function of the electromagnetic current J em μ and the electric component of the tensor current T μ ν . To that end we employ the gauge ensembles obtained by using N f = 2 + 1 + 1 Wilson-Clover twisted-mass quark flavors, generated by the Extended Twisted Mass (ETM) Collaboration, and after adding all sources of systematic uncertainties, we obtain a total error of 1.5% and 3.5%, respectively, for the light- ( u and d ) and strange-quark contribution to f γ ⊥ ( 2 GeV ) in the MS ¯ scheme, thus improving their accuracy by a factor of 2.3 and 2.8, respectively. For the strange-quark contribution f γ , s ⊥ ( 2 GeV ) , we observe a discrepancy with respect to previous lattice calculations. By combining our result with the world average lattice value of the chiral condensate, we obtain for the susceptibility of the quark condensate χ d MS ¯ ( 2 GeV ) ≃ χ u MS ¯ ( 2 GeV ) = 2.17 ( 12 ) GeV − 2 . Published by the American Physical Society 2024
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Funders: International Council of Shopping Centers Educational Foundation, University of Texas at Austin, University of Bern, European Commission, Partnership for Advanced Computing in Europe AISBL, Ministero dell’Istruzione, dell’Università e della Ricerca, China Scholarship Council, CSC – IT Center for Science, Centro Svizzero di Calcolo Scientifico, National Supercomputing Centre Singapore, Gauss Centre for Supercomputing, HORIZON EUROPE Framework Programme, Leibniz-Gemeinschaft, Instituto Nazionale di Fisica Nucleare, Leibniz-Rechenzentrum
OpenAlex ID: W4394906500