Measurement of x, Q(2) and hydrogen-deuterium dependence of R=sigma(L)/sigma(T)

The ratio of R = sigmaL/sigma T in the range 0.1 ≤ x ≤ 0.7 and 0.5 ≤ Q2 ≤ 7.0 (Gev)2 was determined for hydrogen, deuterium and beryllium targets in the SLAC experiment E140X. The cross sections were measured with the 8 GeV spectrometer at momenta between 0.6 and 6.0 GeV and scattering angles between 12° and 59°. The electron beam from the Nuclear Physics Injector in both normal and SLED mode produced electron energies in the range from 2.0 GeV to 10.0 GeV. The measurement has given R values at small x with low Q2, compared R value of hydrogen with deuterium, and determined higher twist contributions beyond QCD and target mass effect at large x. The results are consistent with a previous empirical fit from SLAC global analysis. Comparisons between the measured data and theoretical calculations are presented.