Sarah Andreas

WIMP dark matter, Higgs exchange and DAMA

In the WIMP scenario, there is a one-to-one relation between the dark matter (DM) relic density and spin-independent direct detection rate if both the annihilation of DM and its elastic scattering on nuclei go dominantly through Higgs exchange. In particular, for DM masses much smaller than the Higgs boson mass, the ratio of the relevant cross sections depends only on the DM mass. Assuming DM mass and direct detection rate within the ranges allowed by the recent DAMA collaboration results—taking account of the channelling effect on energy threshold and the null results of the other direct detection experiments—gives a definite range for the relic density. For scalar DM models, like the Higgs portal models or the inert doublet model, the relic density range turns out to be in agreement with WMAP. This scenario implies that the Higgs boson has a large branching ratio to pairs of DM particles, a prediction which might challenge its search at the LHC.

Light scalar WIMP through the Higgs portal and CoGeNT

If dark matter (DM) simply consists in a scalar particle interacting dominantly with the Higgs boson, the ratio of its annihilation cross section---which is relevant both for the relic abundance and indirect detection---and its spin-independent scattering cross section on nuclei depends only on the DM mass. It is an intriguing result that, fixing the mass and direct detection rate to fit the annual modulation observed by the DAMA experiment, one obtains a relic density in perfect agreement with its observed value. In this article we update this result and confront the model to the recent CoGeNT data, tentatively interpreting the excess of events in the recoil energy spectrum as being due to DM. CoGeNT, as DAMA, points toward a light DM candidate, with somewhat different (but not necessarily incompatible) masses and cross sections. For the CoGeNT region too, we find an intriguing agreement between the scalar DM relic density and direct detection constraints. We give the

Constraints on a very light CP{odd Higgs of the NMSSM and other axion{like particles

1\ensuremath{\sigma}

Hidden photons in connection to dark matter

region favored by the CDMS-II events, and our exclusion limits for the Xenon10 (2009) and Xenon100 data, which, depending on the scintillation efficiency, may exclude CoGeNT and DAMA. Assuming CoGeNT and/or DAMA to be due to scalar singlet DM leads to definite predictions regarding indirect detection and at colliders. We specifically emphasize the limit on the model that might be set by the current Fermi-LAT data on dwarf galaxies, and the implications for the search for the Higgs at the LHC.

Dark Forces and Dark Matter in a Hidden Sector

In the NMSSM, a light CP-odd Higgs arises due to spontaneous breaking of approximate symmetries such as Peccei-Quinn or R-symmetry and is motivated by string theory. The case when it is heavier than two muons is well studied and constrained. We analyze various meson decay, g − 2, beam dump and reactor bounds on the CP-odd Higgs with mass below the muon threshold, in particular, addressing the question how light a CP-odd Higgs can be. We find that it has to be heavier than 210 MeV or have couplings to fermions 4 orders of magnitude below those of the Standard Model Higgs. Our analysis applies more generally to couplings of a light pseudoscalar to matter.

Neutrino signature of Inert Doublet Dark Matter

Light extra U(1) gauge bosons, so called hidden photons, which reside in a hidden sector have attracted much attention since they are a well motivated feature of many scenarios beyond the Standard Model and furthermore could mediate the interaction with hidden sector dark matter. We review limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay. In addition, we study the possibility of having dark matter in the hidden sector. A simple toy model and different supersymmetric realisations are shown to provide viable dark matter candidates in the hidden sector that are in agreement with recent direct detection limits.

New Limits on Hidden Photons from Past Electron Beam Dumps

Hidden sectors in connection with GeV-scale dark forces and dark matter are not only a common feature of physics beyond the Standard Model such as string theory and SUSY but are also phenomenologically of great interest regarding recent astrophysical observations. The hidden photon in particular is also searched for and constrained by laboratory experiments, the current status of which will be presented here. Furthermore, several models of hidden sectors containing in addition a dark matter particle will be examined regarding their consistency with the dark matter relic abundance and direct detection experiments.

Neutrinos from Inert Doublet dark matter

In the framework of the Inert Doublet Model and extensions, the signature of neutrinos from dark matter annihilation in the Earth, the Sun and at the Galactic centre is presented. The model contains an extra Higgs doublet, a neutral component of which is chosen as dark matter candidate. There are three distinct mass ranges for which consistency both with WMAP abundance and direct searches can be obtained: a low (4–8 GeV), a middle (60–70 GeV) and a high (500–1500 GeV) WIMP mass range. The first case is of interest as we showed that the model can at the same time give the correct WMAP abundance and account for the positive DAMA results without contradicting other direct searches. We present how capture in the Sun can further constrain this scenario using Super‐Kamiokande data. Indirect detection through neutrinos is challenging for the middle and high mass ranges. For the former, the presence of the so‐called ‘iron resonance’ gives rise to larger neutrino fluxes for WIMP masses around 60–70 GeV since captu...