Abstract
We present a new formulation of pseudoscalar meson loop corrections to nucleon parton distributions within a nonlocal covariant chiral effective field theory, including contributions from SU(3) octet and decuplet baryons. The nonlocal Lagrangian, constrained by requirements of local gauge invariance and Lorentz-invariant ultraviolet regularization, generates additional interactions associated with gauge links. We use these to compute the full set of proton $\to$ meson + baryon splitting functions, which in general contain on-shell and off-shell contributions, in addition to $\delta$-function terms at zero momentum, along with nonlocal contributions associated with the finite size of the proton. We illustrate the shapes of the various local and nonlocal functions numerically using a simple example of a dipole regulator.
Highlights
The important role played by chiral symmetry in hadron physics has been documented for many decades
We present a new formulation of pseudoscalar meson loop corrections to nucleon parton distributions within a nonlocal covariant chiral effective field theory, including contributions from SU(3) octet and decuplet baryons
In this paper we have for the first time used a nonlocal covariant formulation of SU(3) chiral effective theory to construct the framework necessary for systematically computing the contributions from pseudoscalar meson loops to parton distributions in the nucleon
Summary
The important role played by chiral symmetry in hadron physics has been documented for many decades. The presence of gauge links in the nonlocal Lagrangian connecting different spacetime coordinates generates additional diagrams which are needed to ensure the local gauge invariance of the theory This guarantees that the proton and neutron charges, for example, are unaffected by meson loops, or that contributions to the strangeness in the nucleon from diagrams with intermediate state kaons and hyperons sum to zero. In this paper we describe how the nonlocal formulation of the chiral SU(3) effective theory can be used to derive the contributions from pseudoscalar meson loops to PDFs in the nucleon We include both the SU(3) octet and decuplet baryons, using a covariant regulator generated through the nonlocal Lagrangian that respects Lorentz and gauge symmetry. V we summarize our results and outline future applications of the new formalism
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