Sneutrino identification in dilepton events at the LHC

Abstract

Heavy neutral resonances appearing in the clean Drell-Yan channel may be the first new physics to be observed at the proton-proton CERN LHC. If a new resonance is discovered at the LHC as a (narrow) peak in the dilepton invariant mass distribution, the characterization of its spin and couplings will proceed via the measurement of production rates and angular distributions of the decay products. We discuss the discrimination of a spin-0 resonance (sneutrino) predicted by supersymmetric theories with R-parity breaking against the spin-1 of Z^\prime bosons and the Randall-Sundrum graviton resonance (spin-2) with the same mass and producing the same number of events under the observed peak. To assess the region of sneutrino parameters (couplings and masses) where the spin determination can be performed to a given confidence level, we focus on the event rate and the angular distributions of the Drell-Yan leptons, in particular using the center-edge asymmetry, A_{\rm CE}. We find that although the measured event rate permits solving the above problem partially, the center-edge asymmetry, on the contrary allows to differentiate the various spins entirely with a minimal number of events around 200.