Cubic color charge correlator in a proton made of three quarks and a gluon

Abstract

The three point correlation function of color charge densities is evaluated explicitly in light cone gauge for a proton on the light cone. This includes both $C$-conjugation even and odd contributions. We account for perturbative corrections to the three-quark light cone wave function due to the emission of an internal gluon which is not required to be soft. We verify the Ward identity as well as the cancellation of UV divergences in the sum of all diagrams so that the correlator is independent of the renormalization scale. It does, however, exhibit the well known soft and collinear singularities. The expressions derived here provide the $C$-odd contribution to the initial conditions for high-energy evolution of the dipole scattering amplitude to small $x$. Finally, we also present a numerical model estimate of the impact parameter dependence of quantum color charge three-point correlations in the proton at moderately small $x$.

Comments: v2: additional author, and new fig.8 with a numerical result for the impact parameter dependence of the C-odd correlator; to be published in PRD; v3: fixed symmetry factors for "fig.7 type" diagrams. arXiv admin note: text overlap with arXiv:2010.11245