Hard Photodisintegration of a Proton Pair

TL;DR

This study investigates high-energy photodisintegration of proton pairs, confirming the s-11 scaling predicted by the constituent counting rule and revealing unique energy-dependent structures not seen in deuteron disintegration.

Contribution

First experimental observation of s-11 scaling in proton-pair photodisintegration at high energies, highlighting differences from deuteron disintegration.

Findings

Confirmed s-11 scaling at higher energies

Cross section lower than deuteron disintegration

Observed energy-dependent structure below scaling region

Abstract

We present a study of high energy photodisintegration of proton-pairs through the gamma + 3He -> p+p+n channel. Photon energies from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s-11 scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For photon energies below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration.