The spatial string tension and dimensional reduction in QCD

We calculate the spatial string tension in ($2+1$) flavor QCD with physical strange quark mass and almost physical light quark masses using lattices with temporal extent N_τ=4, 6 and 8. We compare our results on the spatial string tension with predictions of dimensionally reduced QCD. This suggests that also in the presence of light dynamical quarks dimensional reduction works well down to temperatures 1.5Tc.