Nuclear effects on R=σL/σT in deep-inelastic scattering

Cross section ratios for deep-inelastic scattering from 14N and 3He with respect to 2H have been measured by the HERMES experiment at DESY using a 27.5 GeV positron beam. The data cover a range in the Bjorken scaling variable x between 0.013 and 0.65, while the negative squared four-momentum transfer Q2 varies from 0.5 to 15 GeV2. The data are compared to measurements performed by NMC, E665, and SLAC on 4He and 12C, and are found to be different for x<0.06 and Q2<1.5 GeV2. The observed difference is attributed to an A-dependence of the ratio R=σL/σT of longitudinal to transverse deep-inelastic scattering cross sections at low x and low Q2.