A 119-125 GeV Higgs from a string derived slice of the CMSSM

We perform a detailed study of the signal rate of the lightest Higgs boson in the diphoton channel (µ γγ ), recently analyzed by both the ATLAS and CMS collaborations at the Large Hadron Collider, in the framework of U(1) R − lepton number model with a right handed neutrino superfield. The corresponding neutrino Yukawa coupling, 'f ', plays a very important role in the phenomenology of this model. A large value of f ∼ O(1) provides an additional tree level contribution to the lightest Higgs boson mass along with a very light (mass ∼ a few hundred MeV) bino like neutralino and a small tree level mass of one of the active neutrinos that is compatible with various experimental results. In the presence of this light neutralino, the total decay width of the Higgs boson and its various branching fractions are affected. When studied in conjunction with the recent LHC results, these put significant constraints on the parameter space. The signal rate µ γγ obtained in this scenario is compatible with the recent results from both the ATLAS and the CMS collaborations at 1σ level. A small value of 'f ', on the other hand, is compatible with a sterile neutrino acting as a 7 keV dark matter that can explain the observation of a mono-energetic X-ray photon line by the XMM-Newton X-ray observatory. Because of the absence of a light neutralino, the total decay width of the lightest Higgs boson in this case remains close to the SM expectation. Hence, in the small 'f ' scenario we obtain a relatively larger value of µ γγ which is closer to the central values reported recently by these two collaborations.

Section: Jhep02(2015)124mentioning

confidence: 99%

h → γγ in U(1) R -lepton number model with a right-handed neutrino

Chakraborty

Datta

Roy

2015

“…This particular choice is taken from [97]. Note that the general results depend very weakly on the choice of spectrum.…”

Section: Example Of Mssm Spectrummentioning

confidence: 99%

AdS-phobia, the WGC, the Standard Model and Supersymmetry

Gonzalo

Herráez

Ibáñez

2018

It has been recently argued that an embedding of the SM into a consistent theory of quantum gravity may imply important constraints on the mass of the lightest neutrino and the cosmological constant Λ 4 . The constraints come from imposing the absence of any non-SUSY AdS stable vacua obtained from any consistent compactification of the SM to 3 or 2 dimensions. This condition comes as a corollary of a recent extension of the Weak Gravity Conjecture (WGC) by Ooguri and Vafa. In this paper we study T 2 /Z N compactifications of the SM to two dimensions in which SM Wilson lines are projected out, leading to a considerable simplification. We analyze in detail a T 2 /Z 4 compactification of the SM in which both complex structure and Wilson line scalars are fixed and the potential is only a function of the area of the torus a 2 . We find that the SM is not robust against the appearance of AdS vacua in 2D and hence would be by itself inconsistent with quantum gravity. On the contrary, if the SM is embedded at some scale M SS into a SUSY version like the MSSM, the AdS vacua present in the non-SUSY case disappear or become unstable. This means that WGC arguments favor a SUSY version of the SM, independently of the usual hierarchy problem arguments. In a T 2 /Z 4 compactification in which the orbifold action is embedded into the B − L symmetry the bounds on neutrino masses and the cosmological constant are recovered. This suggests that the MSSM should be extended with a U(1) B−L gauge group. In other families of vacua the spectrum of SUSY particles is further constrained in order to avoid the appearance of new AdS vacua or instabilities. We discuss a possible understanding of the little hierarchy problem in this context.

“…The total density of cold dark matter is very tightly constrained by measurements of the cosmic microwave background radiation [13]. It is clear, therefore, that the parameters of generic models are constrained in very specific ways in order to realize the correct dark matter density [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Moreover, this parameter space with the correct density is likely to be found in a region of parameter space where the density varies rapidly with the parameters.…”

Section: Introductionmentioning

confidence: 99%

Scenarios for gluino coannihilation

Ellis

Evans

Luo

et al. 2016

We study supersymmetric scenarios in which the gluino is the next-to-lightest supersymmetric particle (NLSP), with a mass sufficiently close to that of the lightest supersymmetric particle (LSP) that gluino coannihilation becomes important. One of these scenarios is the MSSM with soft supersymmetry-breaking squark and slepton masses that are universal at an input GUT renormalization scale, but with non-universal gaugino masses. The other scenario is an extension of the MSSM to include vector-like supermultiplets. In both scenarios, we identify the regions of parameter space where gluino coannihilation is important, and discuss their relations to other regions of parameter space where other mechanisms bring the dark matter density into the range allowed by cosmology. In the case of the non-universal MSSM scenario, we find that the allowed range of parameter space is constrained by the requirement of electroweak symmetry breaking, the avoidance of a charged LSP and the measured mass of the Higgs boson, in particular, as well as the appearance of other dark matter (co)annihilation processes. Nevertheless, LSP masses m χ 8 TeV with the correct dark matter density are quite possible. In the case of pure gravity mediation with additional vector-like supermultiplets, changes to the anomalymediated gluino mass and the threshold effects associated with these states can make the gluino almost degenerate with the LSP, and we find a similar upper bound.