Density dependence of 2p-2h meson-exchange currents

TL;DR

This paper investigates how meson-exchange currents affect lepton-nucleus interactions, revealing a specific density-dependent scaling behavior in the 2p-2h channel within a relativistic Fermi gas model.

Contribution

It provides a detailed analysis of the density dependence of 2p-2h meson-exchange currents using a relativistic Fermi gas model, highlighting a distinct scaling behavior different from quasielastic responses.

Findings

2p-2h response scales as A k_F^2

Quasielastic response scales as A/k_F

Deep scaling region shows usual behavior

Abstract

We analyze the density dependence of the contribution of meson-exchange currents to the lepton-nucleus inclusive cross section in the two-particle two-hole channel. The model is based on the Relativistic Fermi Gas, where each nucleus is characterized by its Fermi momentum $k_F$. We find that the 2p-2h nuclear response functions at their peaks scale as $A k_F^2$ for Fermi momentum going from 200 to 300 MeV/c and momentum transfer $q$ from $2k_F$ to 2 GeV/c. This behavior is different from what is found for the quasielastic response, which scales as $A/k_F$. Additionally, the deep scaling region is also discussed and there the usual scaling behavior is found to be preferable.