MC tuning with low-x low-Q$^2$ higher twists HHT PDF from HERA

In the HHT QCD fit the standard DGLAP evolution was augmented by including an additional low-x higher-twist term in the description of the longitudinal structure function, FL. This additional term significantly improves the description of the HERA reduced cross sections at low Bjorken-x and low four-momentum-transfer squared, Q$^2$. Since the HHT fit describes well data from the highest Q$^2$ down to Q$^2$ of a few GeV$^2$, it can be used in studies to tune MC samples using the LHC underlying event variables. Preliminary trsults of this tuning will be shown in this presentation