Massive spin-2 scattering amplitudes in extra-dimensional theories

Abstract

2 Our discussion here follows closely the review in Sec. 8 of [21]. 3 Note that the mass of the graviton is stringently constrained by gravitational wave experiments to be m < 1.22 × 10 −22 eV/c 2 [23]. 4 The relative coefficients between the two terms in the mass term are chosen to avoid propagating ghost degrees of freedom. For more details, consult footnote 7.

Kaluza-Klein FIMP dark matter in warped extra-dimensions

“…As a consequence of such lower Planck scale in extra-dimensional models (either fundamental or effective), the gravitational interaction is enhanced, and a DM particle with just such interaction could become a WIMP, that is, a stable or cosmologically long-lived weakly interactive massive particle, with mass typically in the range 100 -1000 GeV, and whose relic abundance is set via the freeze-out mechanism. This possibility has been thoroughly studied in the framework of the RS scenario [16][17][18][19][20][21][22][23][24][25] and in a series of recent papers that study generic spin-2 mediators [26][27][28][29]. It has also been considered in the context of the CW/LD model [30].…”

“…Within the same approximations as in the previous subsection, i.e., assuming that KK-gravitons and radions are produced out of chemical equilibrium from the SM bath via inverse-decays, and the evolution of the DM yield is largely dominated by their decays, eqs. (3.4) to (3.6) can be simplified to: 27) where the interaction rate densities for decays are defined by:…”

Unitarity in KK-graviton production, a case study in warped extra-dimensions

“…Most particle phenomenology inspired investigations of extra-dimensional models are chiefly interested in the role of the spin-2 fields as mediators between initial and final states consisting of matter fields [9][10][11]. In contrast, studies motivated by a more theoretical interest in massive spin-2 fields have recently investigated the physics of KK-graviton scattering [12][13][14][15].…”

Lightening gravity-mediated dark matter

“…As we mentioned in the beginning of the section, there also appear non-linear interactions of KK gravitons in the 4D effective theory, contributing to the DM annihilation channels, such as DM DM → GG. There have been attempts to tackle the unitarity bound on the non-linear interactions of a massive spin-2 particle in the dRGT realization of the massive spin-2 particle [43,89,90] or include the non-linear interactions in the scattering amplitudes of KK gravitons in the RS model [101].…”