Onset of Asymptotic Scaling in Deuteron Photodisintegration

Abstract

We investigate the transition from the nucleon-meson to the quark-gluon description of the strong interaction using the photon energy dependence of the $d(\ensuremath{\gamma},p)n$ differential cross section for photon energies above 0.5 GeV and center-of-mass proton angles between 30\ifmmode^\circ\else\textdegree\fi{} and 150\ifmmode^\circ\else\textdegree\fi{}. A possible signature for this transition is the onset of cross-section ${s}^{\ensuremath{-}11}$ 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 $1.1\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$. This may indicate that the quark-gluon regime is reached above this momentum.