Proton Transparency and Neutrino Physics: New Methods and Modeling

TL;DR

This paper introduces a new data-driven method to measure proton transparency in electron-nucleus scattering, highlighting discrepancies in current simulation models like GENIE, which are crucial for neutrino physics experiments.

Contribution

The study presents a novel measurement technique for proton transparency using electron scattering data and demonstrates the need for improved modeling in neutrino interaction simulations.

Findings

Measured proton transparency across helium, carbon, and iron targets.

Identified deficiencies in GENIE's description of nuclear ground state and rescattering.

Results support refining simulation models for better neutrino experiment accuracy.

Abstract

Extracting accurate results from neutrino oscillation and cross section experiments requires accurate simulation of the neutrino-nucleus interaction. The rescattering of outgoing hadrons (final state interactions) by the rest of the nucleus is an important component of these interactions. We present a new measurement of proton transparency (defined as the fraction of outgoing protons that emerge without significant rescattering) using electron-nucleus scattering data recorded by the CLAS detector at Jefferson Laboratory on helium, carbon, and iron targets. This analysis by the Electrons for Neutrinos ($e4\nu$) collaboration uses a new data-driven method to extract the transparency. It defines transparency as the ratio of electron-scattering events with a detected proton to quasi-elastic electron-scattering events where a proton should have been knocked out. Our results are consistent with previous measurements that determined the transparency from the ratio of measured events to theoretically predicted events. We find that the GENIE event generator, which is widely used by oscillation experiments to simulate neutrino-nucleus interactions, needs to better describe both the nuclear ground state and proton rescattering in order to reproduce our measured transparency ratios, especially at lower proton momenta.