2014/12/31 by Kaustubh Agashe, Chien-Yi Chen, Hooman Davoudiasl +1
Physics and Astronomy · #Black Holes and Theoretical Physics #Branching fraction #Cascade #Cosmology and Gravitation Theories #Graviton #Hadron #Invariant mass #Large Hadron Collider #Nuclear physics #Particle decay #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Quantum mechanics #Standard Model (mathematical formulation) #hep-ph
paper · pdf · doi:10.1103/physrevd.91.076002
published as Phys. Rev. D 91, 076002 (2015) · 25 pages, 5 figures and 2 tables, various editorial changes, references added, physics results and conclusions unchanged
arxiv created 2015/01/22 · openalex publication_date 2015/04/06 · arxiv updated 2015/04/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In warped 5D models of hierarchy and flavor, the first Kaluza-Klein (KK) state of the graviton G1 is heavy enough to decay into a photon and its first KK mode \ensuremathγ1 on-shell: G1\ensuremath→\ensuremathγ1\ensuremathγ. The volume-suppression of the rate for this process [relative to 2-body decay into heavy Standard Model (SM) final states (W/Z/t/H)] may be partially compensated by the simplicity of the photon final state. We consider \ensuremathγ1\ensuremath→W+W^\ensuremath-, with a typical O(1) branching fraction, and focus on the semileptonic final state W(\ensuremath→jj)W(\ensuremath→\ensuremathℓ,\ensuremathν) with \ensuremathℓ=e,\ensuremathμ. The SM background originates from 2\ensuremath→3 parton processes and is relatively suppressed compared to those for 2-body decays of G1. Moreover, to further reduce the background, we can impose an invariant mass window cut for \ensuremathγ1 (in addition to that for G1) in this new channel. We emphasize that this ``photon cascade" decay probes a different combination of (bulk and brane) interactions of the KK states than the decays into two heavy SM states. Thus, in combination with other channels, the cascade decay could be used to extract the individual underlying geometric parameters. The 3\ensuremathσ reach for G1 in our channel is up to 1.5 TeV at the high luminosity (14 TeV) LHC, and can be extended to about 4 TeV, at 5\ensuremathσ, at a future 100 TeV hadron collider. Along the way, we point out the novel feature that the invariant mass distribution of KK graviton decay products becomes skewed from the Breit-Wigner form, due to the KK graviton coupling growing with energy.