Spin identification of the Randall-Sundrum resonance in lepton-pair production at the LHC

Abstract

The determination of the spin of the quantum states exchanged in the various non-standard interactions is a relevant aspect in the identification of the corresponding scenarios. We discuss the identification reach at LHC on the spin-2 of the lowest-lying Randall-Sundrum resonance, predicted by gravity with one warped extra dimension, against spin-1 and spin-0 non-standard exchanges with the same mass and producing the same number of events in the cross section. We focus on the angular distributions of leptons produced in the Drell-Yan process at the LHC, in particular we use as basic observable a normalized integrated angular asymmetry A_{CE}. Our finding is that the 95% C.L. identification reach on the spin-2 of the RS resonance (equivalently, the exclusion reach on both the spin-1 and spin-0 hypotheses for the peak) is up to a resonance mass scale of the order of 1.0 or 1.6 TeV in the case of weak coupling between graviton excitations and SM particles (k/{\bar M}_{Pl}=0.01) and 2.4 or 3.2 TeV for larger coupling constant (k/{\bar M}_{Pl}=0.1) for a time-integrated LHC luminosity of 10 or 100 fb^{-1}, respectively. Also, some comments are given on the complementary rôles of the angular analysis and the eventual discovery of the predicted second graviton excitation in the identification of the RS scenario.

Comments: 27 pages, 11 figures. v2: References added, clarifications; version to appear in PRD