Onset of the color transparency (CT) at 12 GeV in Hall C at Jefferson Lab*

Color Transparency (CT)  is a unique prediction of QCD where the final (and/or initial) state interactions of hadrons with the nuclear medium are suppressed for exclusive processes at high momentum transfers. The onset of CT has never been conclusively observed for baryons. A clear signal for the onset of CT for baryons would show the transition from the nucleon-meson picture to quark-gluon degrees of freedom.

Experiment E12-06-107 seeks to measure proton transparency (PT) using the A(e, e'p) proton knockout reaction with the recently upgraded 12 GeV e^- beam along with HMS and SHMS spectrometers in HallC at JLab.  Data were collected on a ¹²C target over the range of Q² = 8 – 14.3 (GeV/c)² covering the region where a previous A(p,2p) experiment at BNL had observed an enhancement. Additional data on ¹H target were collected to determine the elementary process.  A rise in the PT as a function of Q² is predicted to be a signature of the onset of CT.