Relativistic effects in two-particle emission for electron and neutrino reactions

TL;DR

This paper develops a relativistic model for two-particle emission in electron and neutrino reactions, analyzing kinematic effects and computational methods to improve predictions for neutrino scattering experiments.

Contribution

It introduces a fully relativistic Fermi gas model for 2p-2h responses, focusing on mathematical properties and numerical techniques for efficient computation.

Findings

Analyzed relativistic effects in 2p-2h responses

Developed an optimized numerical integration method

Assessed the model's applicability to neutrino scattering

Abstract

Two-particle two-hole contributions to electroweak response functions are computed in a fully relativistic Fermi gas, assuming that the electroweak current matrix elements are independent of the kinematics. We analyze the genuine kinematical and relativistic effects before including a realistic meson-exchange current (MEC) operator. This allows one to study the mathematical properties of the non-trivial seven-dimensional integrals appearing in the calculation and to design an optimal numerical procedure to reduce the computation time. This is required for practical applications to CC neutrino scattering experiments, where an additional integral over the neutrino flux is performed. Finally we examine the viability of this model to compute the electroweak 2p-2h response functions.