Ruling out color transparency in quasi-elastic $^{12}$C(e,e'p) up to $Q^2$ of 14.2 (GeV/c)$^2$

TL;DR

This study measured quasielastic electron scattering off carbon at high momentum transfers up to 14.2 (GeV/c)^2, finding no evidence of color transparency effects, thus constraining theoretical models in quantum chromodynamics.

Contribution

It provides the highest $Q^2$ measurements of nuclear transparency in $(e,e'p)$ reactions, showing no $Q^2$ dependence and ruling out color transparency at these scales.

Findings

Nuclear transparency remains constant up to $Q^2$ of 14.2 (GeV/c)^2.

No evidence of color transparency effects observed.

Results impose constraints on QCD models of proton behavior.

Abstract

Quasielastic $^{12}$C$(e,e'p)$ scattering was measured at space-like 4-momentum transfer squared $Q^2$~=~8, 9.4, 11.4, and 14.2 (GeV/c)$^2$, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no $Q^2$ dependence, up to proton momenta of 8.5~GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured $Q^2$ scales in exclusive $(e,e'p)$ reactions. These results impose strict constraints on models of color transparency for protons.