Observation of azimuth-dependent suppression of hadron pairs in electron scattering off nuclei

TL;DR

This study measures di-hadron angular correlations in electron-nucleus scattering, revealing azimuth-dependent suppression and enhancement effects that grow with nuclear size, providing new insights into hadron formation and interactions within nuclei.

Contribution

First measurement of di-hadron angular correlations in electron-nucleus scattering, demonstrating azimuth-dependent suppression and enhancement effects related to nuclear size.

Findings

Suppression of azimuthally opposite charged-pion pairs in heavier nuclei.

No suppression for azimuthally nearby pairs.

Enhancement of pairs with large invariant mass in larger nuclei.

Abstract

We present the first measurement of di-hadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the GiBUU model, which suggests that hadrons form near the nuclear surface and undergo multiple-scattering in nuclei. These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei