Onset of asymptotic scaling in deuteron photodisintegration

Phys Rev Lett. 2005 Jan 14;94(1):012301. doi: 10.1103/PhysRevLett.94.012301. Epub 2005 Jan 6.


We investigate the transition from the nucleon-meson to the quark-gluon description of the strong interaction using the photon energy dependence of the d(gamma,p)n differential cross section for photon energies above 0.5 GeV and center-of-mass proton angles between 30 degrees and 150 degrees. A possible signature for this transition is the onset of cross-section s(-11) scaling with the total energy squared, s, at some proton transverse momentum P(T). The results show that the scaling has been reached for proton transverse momentum above about 1.1 GeV/c. This may indicate that the quark-gluon regime is reached above this momentum.