PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY
Abstract
The high mass neutral quantum states envisaged by theories of
physics beyond the standard model can at the hadron colliders
reveal themselves through their decay into a pair of photons. Once such a peak in the diphoton invariant mass distribution is
discovered, the determination of its spin through the distinctive
photon angular distributions is needed in order to identify the
associated nonstandard dynamics. We here discuss the
discrimination of the spin-2 Randall-Sundrum graviton excitation
against the hypothesis of a spin-0 exchange giving the same number of events under the peak, by means of the angular analysis applied to resonant diphoton events expected to be observed at the LHC.
The spin-0 hypothesis is modelled by an effective interaction of a
high mass, gauge singlet, scalar particle interacting with the
standard model fields. The basic observable of our analysis is the
symmetrically integrated angular asymmetry A_CE,
calculated for both graviton and scalar s-channel exchanges
to next-to-leading order in QCD.
