Are there hints of light stops in recent Higgs search results?

Abstract

The recent discovery at the LHC by the CMS and ATLAS collaborations of the Higgs boson presents, at long last, direct probes of the mechanism for electroweak symmetry breaking. While it is clear from the observations that the new particle plays some role in this process, it is not yet apparent whether the couplings and widths of the observed particle match those predicted by the Standard Model. In this paper, we perform a global fit of the Higgs results from the LHC and Tevatron. While these results could be subject to as-yet-unknown systematics, we find that the data are significantly better fit by a Higgs with a suppressed width to gluon-gluon and an enhanced width to , relative to the predictions of the Standard Model. After considering a variety of new physics scenarios which could potentially modify these widths, we find that the most promising possibility is the addition of a new colored, charged particle, with a large coupling to the Higgs. Of particular interest is a light, and highly mixed, stop, which we show can provide the required alterations to the combination of gg and widths.

Gamma rays from bino-like dark matter in the MSSM

“…However, it does affect the overall scale of the annihilation cross section; if this coupling is required to be perturbative, then σ (γγ,γZ) can be increased by up to 4 orders of magnitude, in agreement with the limit discussed in Ref. [3]. For models with small R th , such an enhancement could bring a line signal within the reach of GAMMA-400.…”

“…In light of recent analyses of data from the Fermi Large Area Telescope (LAT) [1] indicating the possibility of an excess of ∼ 130 GeV photons from the Galactic Center region [2], there has been renewed interest in dark matter models that can produce monoenergetic photons through the processes χχ → γγ, γZ, and γh [3][4][5][6][7][8][9]. Generically, one would expect models with a monoenergetic photon line to be accompanied by a larger continuum photon spectrum.…”

“…Many new dark matter models have been proposed to evade these constraints and explain the recent Fermi data [3,4]. Similarly, a variety of works have studied the question of whether it is possible for the 130 GeV photon excess seen by Fermi to be produced within the MSSM [5][6][7] or singlet extensions of the MSSM [8], while maintaining consistency with bounds on the continuum spectrum.…”

Stringent constraints on the dark matter annihilation cross section from the region of the Galactic Center

“…13, we consider this case and find a resulting constraint of (σv/m 2 DM ) 100GeV 10GeV dE γ dN γ /dE γ < 3.6×10 −31 cm 3 s −1 GeV −2 , which is more stringent than in the on-center Einasto case by a factor of approximately 2.5. This makes a dark matter annihilation explanations of the observed 130 GeV gamma-ray line very difficult to accommodate with dark matter candidates which possess any significant annihilation cross section to non-line final states [50][51][52]. Contour maps of the gamma-ray flux from the region surrounding the Galactic Center, after subtracting varying degrees of emission from dark matter distributed according to an NFW profile with a 1 kiloparsec, constant-density core.…”

Exotic leptons: Higgs, flavor and collider phenomenology

“…On the other hand, extensions of the SM with vector-like leptons which couple to the Higgs, can both enhance and suppress the h → γγ decay rate, because in contrast to chiral leptons, vector-like leptons can interfere also constructively with the W contribution. Colored new matter is additionally constrained by data, because it also affects the gluon fusion production cross section of the Higgs, which in turn leads to modifications of all Higgs signal strengths [7,9,14,25,26,28,[43][44][45][46][47].…”