The non-perturbative effect on R=σL/σT from QCD vacuum

We investigate the non-perturbative effects on the ratio R=σL/σT in lepton-nucleon deep inelastic scattering by taking into account the lowest dimensional condensate contributions from the QCD vacuum. By combining conventional perturbative QCD corrections and the Georgi-Politzer target-mass effects with the non-perturbative effects from the QCD vacuum, we give a good description of the Q2 and x dependences of R in comparison with the recent experimental data.