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Gluon contributions to the pion mass and light cone momentum fraction

Harvey B. Meyer, John W. Negele

Abstract

We calculate the matrix elements of the gluonic contributions to the energy-momentum tensor for a pion of mass 600 < Mpi < 1100 MeV in quenched lattice QCD. We find that gluons contribute (37 +/- 8 +/- 12)% of the pion's light cone momentum. The bare matrix elements corresponding to the trace anomaly contribution to the pion mass are also obtained. The discretizations of the energy-momentum tensor we use have other promising applications, ranging from calculating the origin of hadron spin to QCD thermodynamics.

Gluon contributions to the pion mass and light cone momentum fraction

Abstract

We calculate the matrix elements of the gluonic contributions to the energy-momentum tensor for a pion of mass 600 < Mpi < 1100 MeV in quenched lattice QCD. We find that gluons contribute (37 +/- 8 +/- 12)% of the pion's light cone momentum. The bare matrix elements corresponding to the trace anomaly contribution to the pion mass are also obtained. The discretizations of the energy-momentum tensor we use have other promising applications, ranging from calculating the origin of hadron spin to QCD thermodynamics.

Paper Structure

This paper contains 11 equations, 2 figures, 2 tables.

Figures (2)

  • Figure 1: A study of cutoff effects: the normalization $\chi(g_0,a/L_0)$ of three discretizations of $\overline T_{00}$ relative to the one based on the bare plaquette as a function of $L_0/a$.
  • Figure 2: The effective gluonic momentum fraction, Eq. \ref{['eq:xeff']}, in a heavy pion, $M_\pi \simeq 1060$MeV.