Supersymmetry explanation of the Fermi Galactic Center excess and its test at LHC run II

Abstract

We explore the explanation of the Fermi Galactic Center excess (GCE) in the next-to-minimal supersymmetric Standard Model. We systematically consider various experimental constraints including the dark matter (DM) relic density, DM direct detection results, and indirect searches from dwarf galaxies. We find that, for DM with mass ranging from 30 to 40 GeV, the GCE can be explained by the annihilation XX a* bb only when the CP-odd scalar satisfies ma -2mx, and in order to obtain the measured DM relic density, a sizable Z-mediated contribution to DM annihilation must intervene in the early universe. As a result, the Higgsino mass p is upper bounded by about 350 GeV. Detailed Monte Carlo simulations on the + E f'ss signal from neutralino/chargino associated production at 14-TeV LHC indicate that the explanation can be mostly (completely) excluded at 95% C.L. with an integrated luminosity of 100(200) fb~'. We also discuss the implication of possible large Z coupling to DM for the DM-nucleon spin dependent (SD) scattering cross section, and find that although the current experimental bounds on o f is less stringent than the spin independent results, the future XENON-IT and LZ data may be capable of testing most parts of the GCE-favored parameter region.

Probing a light CP-odd scalar in di-top-associated production at the LHC

“…Recently, CP-odd scalars as mediators between Dark Matter (DM) and SM particles have received attention as possible explanations of the diffuse gamma-ray excess from the Galactic Centre [7][8][9][10] in the contexts of the so-called Coy Dark Matter models [11][12][13][14], and the Next-to-MinimalSupersymmetric-Standard-Model (NMSSM) [15,16] (for subsequent discussions in the NMSSM, see [17][18][19][20][21]). Hence, they are included as mediators in simplified models by the ATLAS and CMS collaborations to recast searches for jets and missing transverse energy ('monojet') during the upcoming LHC runs [22,23].…”

Extending LHC coverage to light pseudoscalar mediators and coy dark sectors

“…Such points can be difficult to sample in a large scan of the parameter space, as employed in refs. [17,109]. However, we have verified that the bino/Higgsino scenario is still in fact viable when taking these constraints into account, as claimed in ref.…”

“…[16] have found somewhat different results, favoring the singlino/Higgsino scenario [17,109]. However, taking the systematics into account in fitting the Fermi signal [12,13], we find that the bino/Higgsino scenario is fully compatible with both the GC signal and the Fermi dwarf spheroidal limits.…”

“…Another reason the bino/Higgsino scenario may have been disfavored in ref. [109] is that the large pseudoscalar couplings to the SM fermions in the bino/Higgsino scenario are constrained by rare meson decays, in particular B s → µ + µ − . As pointed out in ref.…”

Dark matter in leptophilic Higgs models after the LHC run I

“…As expected the cross section decreases as the mass of the pseudoscalar increases, however we can see that there is still a large range of parameters which fit the Galactic Center excess, even when the pseudoscalar and dark matter masses are far from being in resonance. It is notable that a leptophilic Higgs model furnishes a viable mediator between the visible sector and the dark matter which provides a sufficiently large annihilation cross section; in Type-II Higgs models, a Higgs mediator which can explain the Galactic Center anomaly without a resonance enhancement tends to require additional light states which are well-constrained from direct detection and collider searches [106][107][108][109][110][111][112]. As the mediators considered here are leptophilic, such constraints are easily avoided.…”