Astrophysical implications of a visible dark matter sector from a custodially warped GUT
Abstract
We explore, within the warped extra dimensional framework, the possibility of finding antimatter signals in cosmic rays (CRs) from dark matter (DM) annihilation. We find that exchange of order 100 GeV radion, an integral part of this class of models, generically results in a sizable Sommerfeld enhancement of the annihilation rate for DM mass at the TeV scale. No ad hoc dark sector is required to obtain boosted annihilation cross sections and hence signals. Such a mild hierarchy between the radion and DM masses can be natural due to the pseudoGoldstone boson nature of the radion. We study the implications of a Sommerfeld enhancement specifically in warped grand unified theory (GUT) models, where proton stability implies a DM candidate. We show, via a partially unified PatiSalam group, how to incorporate a custodial symmetry for Z→bb¯ into the GUT framework such that a few TeV KaluzaKlein (KK) mass scale is allowed by electroweak precision tests. Among such models, the one with the smallest SO(10) (fully unified) representation, with SU(5) hypercharge normalization, allows us to decouple the DM from the electroweak gauge bosons. Thus, a correct DM relic density can be obtained and direct detection bounds are satisfied. Looking at robust CR observables, we find a possible future signal in the p¯/p flux ratio consistent with current constraints. Using a different choice of representations, we show how to embed in this GUT model a similar custodial symmetry for the righthanded tau, allowing it to be strongly coupled to KK particles. Such a scenario might lead to an observed signal in CR positrons; however, the DM candidate in this case cannot constitute all of the DM in the Universe. As an aside and independent of the GUT or DM model, the strong coupling between KK particles and tau’s can lead to striking LHC signals.
 Publication:

Physical Review D
 Pub Date:
 April 2010
 DOI:
 10.1103/PhysRevD.81.075012
 arXiv:
 arXiv:0912.3070
 Bibcode:
 2010PhRvD..81g5012A
 Keywords:

 12.60.i;
 95.35.+d;
 Models beyond the standard model;
 Dark matter;
 High Energy Physics  Phenomenology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Experiment
 EPrint:
 53 pages, 9 figures