  We provide a new way of constraining the relative scintillation efficiency
L_eff for liquid xenon. Using a simple estimate for the electronic and nuclear
stopping powers together with an analysis of recombination processes we predict
both the ionization and the scintillation yields. Using presently available
data for the ionization yield, we can use the correlation between these two
quantities to constrain L_eff from below. Moreover, we argue that more reliable
data on the ionization yield would allow to verify our assumptions on the
atomic cross sections and to predict the value of L_eff. We conclude that the
relative scintillation efficiency should not decrease at low nuclear recoil
energies, which has important consequences for the robustness of exclusion
limits for low WIMP masses in liquid xenon Dark Matter searches.
