We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.
We explore an extension to the Standard Model which incorporates a vector field in the fundamental representation of SUð2Þ L as the only nonstandard degree of freedom. This kind of field may appear in different scenarios such as compositeness, gauge-Higgs unification, and extradimensional scenarios. We study the model in which a Z 2 symmetry is manifiest, making the neutral CP-even component of the new vector field a vectorial dark matter candidate. We constraint the parameter space through LEP and LHC data, as well as from current dark matter searches. Additionally, comments on the implications of perturbative unitarity are presented. We find that the model is highly constrained but a small region of the parameter space can provide a viable DM candidate. On the other hand, unitarity demands an UV completion at an scale below 10 TeV. Finally we contrast our predictions on mono-jet,-Z,-Higgs production with the ones obtained in the inert two Higgs doublet model.
We consider a scenario of a composite Higgs arising from a strong sector. We
assume that the lowest lying composite states are the Higgs scalar doublet and
a massive vector triplet, whose dynamics below the compositeness scale are
described in terms of an effective Lagrangian. Electroweak symmetry breaking
takes place through a vacuum expectation value just as in the Standard Model,
but with the vector resonances strongly coupled to the Higgs field. We
determine the constraints on this scenario imposed by (i) the Higgs diphoton
decay rate, (ii) the electroweak precision tests and (iii) searches of heavy
resonances at the LHC in the final states $l^+l^-$ and $l\nu_l$ ($l=e,\mu$),
$\tau^+\tau^-$, $jj$, $t\bar{t}$, $WZ$, $WW$, $WH$ and $ZH$. We find that the
heavy vector resonances should have masses that are constrained to be in the
range $2.1$ - $3$ TeV. On the other hand, the mixing of the heavy vectors with
the Standard Model gauge bosons is constrained to be in the range
$\tan\vartheta\sim 0.1 - 0.3$, which is consistent with the assumption that the
Higgs couples weakly to the Standard sector, even though it couples strongly to
the heavy vector resonances.Comment: 14 pages, 18 figures. arXiv admin note: text overlap with
arXiv:1506.0363
We explore a class of simplified extensions to the Standard Model containing a complex singlet scalar as a
dark matter candidate accompanied by a vector-like lepton as a mediator, both charged under a new Z
3 symmetry. In
its simplest form, the new physics couples only to right-handed electrons, and the model is able to accommodate
the correct dark matter relic abundance around the electroweak scale up to several TeV evading the strongest
constraints from perturbativity, collider and dark matter searches. Furthermore, the model is capable to enhance
naturally positron fluxes by several orders of magnitude presenting a box-shape spectra. This framework opens up a lot of phenomenological possibilities depending on the quantum charge assignments of the new fields.
We study a simple dark matter model given by two interacting real singlet scalars, with only one of them coupled to the Higgs. The model therefore presents a minimal assisted -freeze-out framework: both scalars contribute to the dark matter relic density, but only one of them takes part in the elastic scattering with nuclei. This reduces the expected interaction rate in direct detection experiments, in such a way that the model in some regions of the parameter space may evades XENON1T constraints. We explore the model under theoretical (perturbativity, stability potential and unitarity) and experimental constraints (Higgs to invisible, relic density, direct detection), with precise approximations near the Higgs resonance to calculate the averaged annihilation cross section. We show that the model is viable in the Higgs resonance region and for scalar singlet masses of hundreds of GeV.
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