Abstract
Dark Matter (DM) detection prospects at future e^+e^- colliders are reviewed under the assumption that DM particles are fermions of the Majorana or Dirac type. Although the discussion is quite general, one will keep in mind the recently proposed candidate based on an excess of energetic photons observed in the center of our Galaxy with the Fermi-LAT satellite. In the first part we will assume that DM interactions are mediated by vector bosons, Z or Z'. In the case of Z-boson Direct Detection limits force only axial couplings with the DM. This solution can be naturally accommodated by Majorana DM but is disfavored by the GC excess. Viable scenarios can be instead found in the case of Z' mediator. These scenarios can be tested at e^{+}e^{-} colliders through ISR events, e^+e^-rightarrow XX+gamma . A sensitive background reduction can be achieved by using highly polarized beams. In the second part scalar particles, in particular Higgs particles, have been considered as mediators. The case of the SM Higgs mediator is excluded by limits on the invisible branching ratio of the Higgs. On the contrary particularly interesting is the case in which the DM interactions are mediated by the pseudoscalar state A in two Higgs-doublet model scenarios. In this last case the main collider signature is e^+e^-rightarrow HA, Hrightarrow hh, A rightarrow XX.
Highlights
The search for dark matter is of prime importance for our understanding of the universe
A recent study [5] has reported the existence of γ -ray excess from the Galactic Center (GC) which could be interpreted as the signal of the annihilation into bb final states of a Dark Matter (DM) with mass of approximately 35 GeV or the democratic annihilation into SM fermions of a 25 GeV mass DM
For m X above 60 GeV the invisible branching fraction goes below 10 % and can only be excluded at e+e− colliders by using the Z h mode, with Z decaying into lepton pairs, which allows for a precise recoil mass reconstruction
Summary
The search for dark matter is of prime importance for our understanding of the universe. For our investigation we will consider simplified scenarios (see [18,19,20,21,22,23,24,25,26,27,28] for similar approaches) in which a fermionic (Dirac or Majorana) WIMP DM, with mass in the range 30–50 GeV, favored by the GC signal, is coupled either with SM mediators, namely the Z boson or the Higgs, or with BSM mediators, namely Z , scalars and pseudoscalar states from an extended Higgs sector. C (2015) 75:171 tion of a scalar and a pseudoscalar Higgs singlet and a two Higgs-doublet scenario After this we will state our conclusions
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