Ruling Out the Onset of Color Transparency up to Q²=14.2 GeV² in Quasielastic ¹²C(e,e’p) Scattering

Color Transparency (CT) is a prediction of QCD that at high momentum transfer Q^2, a system of quarks which would normally interact strongly with nuclear matter could form a small color-neutral object whose compact transverse size would be maintained for some distance, passing through the nucleus undisturbed. A clear signature of CT would be a dramatic rise in nuclear transparency T with increasing Q^2. CT emerges as a deviation from Glauber multiple scattering theory, which predicts constant T. While a rise in nuclear transparency would provide an unequivocal validation of QCD factorization theorems, the complex nature of nuclear interactions renders its observation difficult to predict. The E12-06-107 experiment at JLab measured T in quasielastic electron-proton scattering with carbon-12 and liquid hydrogen targets, for Q^2 between 8.0 and 14.2 GeV^2, a range over which models of CT predicted that T might differ appreciably from Glauber calculations. Supported in part by US DOE grant DE-FG02-03ER41240.