Detailed analysis of two-boson exchange in parity-violating e-p scattering

TL;DR

This paper provides a detailed analysis of two-boson exchange corrections in parity-violating electron-proton scattering, highlighting the relative importance of nucleon and Delta contributions across different angles and momentum transfers.

Contribution

It offers a comprehensive hadronic calculation of TBE corrections, including Delta baryon effects, and evaluates their impact on experimental measurements.

Findings

Delta contribution dominates at forward angles

Corrections are small (<1%) at low Q^2 but increase at higher Q^2

Total corrections range from -1% to 2% depending on kinematics

Abstract

We present a comprehensive study of two-boson exchange (TBE) corrections in parity-violating electron-proton elastic scattering. Within a hadronic framework, we compute contributions from box (and crossed box) diagrams in which the intermediate states are described by nucleons and Delta baryons. The Delta contribution is found to be much smaller than the nucleon one at backward angles (small epsilon), but becomes dominant in the forward scattering limit (epsilon -> 1), where the nucleon contribution vanishes. The dependence of the corrections on the input hadronic form factors is small for Q^2 < 1 GeV^2, but becomes significant at larger Q^2. We compute the nucleon and Delta TBE corrections relevant for recent and planned parity-violating experiments, with the total corrections ranging from -1% for forward angles to 1-2% at backward kinematics.