Speaker:	Anibal Medina (U Melbourne)
Title:	SUSY Implications from WIMP Annihilation into Scalars at the Galactic Centre
Date (JST):	Fri, Feb 06, 2015, 13:30 - 14:30
Place:	Seminar Room A
Related File:	1363.pdf
Abstract:	An excess in gamma-rays emanating from the galactic centre has recently been observed in the Fermi-LAT data. A possible interpretation of this signal is due to WIMP annihilation, with the spectrum well-fit from dark matter annihilating dominantly to either bottom-quark or Higgs pairs. Supersymmetric models provide a well-motivated framework to study the implications of this signal in these channels. With a neutralino dark matter candidate, the galactic excess can not be easily accommodated in the minimal supersymmetric model, which in any case requires tuning below the percent level to explain the observed Higgs mass. Instead we are naturally led to consider the next-to-minimal model with a singlet superfield. The singlet admixture allows for annihilation via a light pseudoscalar mediator into bottom-quark pairs and the annihilation into a Higgs-pseudoscalar pair is possible because the three-point scalar coupling can now be enhanced. In fact we show that the fit to the Higgs-pseudoscalar channel can be just as good as for the bottom-quark pairs. Moreover, in the parameter range of interest, the next-to-minimal supersymmetric model solves the $⧵mu$-problem and can explain the 125 GeV Higgs mass with improved naturalness. We also consider an extension by adding a right-handed neutrino field with the right-handed sneutrino acting as a possible dark matter candidate. Interestingly this allows for the annihilation into pseudoscalar pairs which also provide a good fit to the gamma-ray spectrum. Furthermore in the case of a neutralino LSP, the late decay of a sneutrino NLSP can non-thermally produce the observed relic abundance.

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