Special supersymmetric features of large invariant mass unpolarized and polarized top-antitop production at the CERN LHC

We consider the top-anti-top invariant mass distributions for production of unpolarized and polarized top quark pairs at LHC, in the theoretical framework of the MSSM. Assuming a "moderately" light SUSY scenario, we derive the leading logarithmic electroweak contributions at one loop in a region of large invariant mass, M(t (t) over bar)similar or equal to 1 TeV, for the unpolarized differential cross section d sigma/dM(t (t) over bar) and for the differential longitudinal top polarization asymmetry A(t)(M-t (t) over bar). We perform a realistic evaluation of the expected uncertainties of the two quantities, both from a theoretical and from an experimental point of view, and discuss the possibility of obtaining, from accurate measurements of the two mass distributions, stringent consistency tests of the model, in particular identifications of large tan beta effects.