Proton and deuteron F[subscript 2] structure function at low Q[superscript 2]

Abstract

Measurements of the proton and deuteron F2 structure functions are presented. The data, taken at Jefferson Lab Hall C, span the four-momentum transfer range 0.06<Q2<2.8 GeV2 and Bjorken x values from 0.009 to 0.45, thus extending the knowledge of F2 to low values of Q2 at low x. Next-to-next-to-leading-order calculations using recent parton distribution functions start to deviate from the data for Q2<2 GeV2 at the low and high x values. Down to the lowest value of Q2, the structure function is in good agreement with a parametrization of F2 based on data that have been taken at much higher values of Q2 or much lower values of x, and which are constrained by data at the photon point. The ratio of the deuteron and proton structure functions at low x remains well described by a logarithmic dependence on Q2 at low Q2.