The Stueckelberg Z prime at the LHC: discovery potential, signature spaces and model discrimination

An analysis is given of the capability of the LHC to detect narrow resonancesusing high luminosities and techniques for discriminating among models arediscussed. The analysis is carried out with focus on the $U(1)_X$ Abelian(Higgless) Stueckelberg extension of the Standard Model (StSM) gauge groupwhich naturally leads to a very narrow $Z'$ resonance. Comparison is made toanother class of models, i.e., models based on the warped geometry which alsolead to a narrow resonance via a massive graviton ($G$). Methods ofdistinguishing the StSM $Z'$ from the massive graviton at the LHC are analyzedusing the dilepton final state in the Drell-Yan process $pp\to Z'\to l^+l^-$and $pp\to G \to l^+l^-$. It is shown that the signature spaces in the $\sigma\cdot Br(l^+l^-) $-resonance mass plane for the $Z$ prime and for the massivegraviton are distinct. The angular distributions in the dilepton C-M system arealso analyzed and it is shown that these distributions lie high above thebackground and are distinguishable from each other. A remarkable result thatemerges from the analysis is the observation that the StSM model with $Z'$widths even in the MeV and sub-MeV range for $Z'$ masses extending in the TeVregion can produce detectable cross section signals in the dilepton channel inthe Drell-Yan process with luminosities accessible at the LHC. While the resultis derived within the specific StSM class of models, the capability of the LHCto probe models with narrow resonances in this range may hold more generally.Comment: 44 page, 14 figure