Effective field theory of dark matter: a global analysis

Sebastian Liem,Roberto Trotta,Christoph Weniger,Francesca Calore,Tim M P Tait,Gianfranco Bertone,Roberto Ruiz De Austri

doi:10.1007/jhep09(2016)077

Abstract

We present global fits of an effective field theory description of real, and complex scalar dark matter candidates. We simultaneously take into account all possible dimension 6 operators consisting of dark matter bilinears and gauge invariant combinations of quark and gluon fields. We derive constraints on the free model parameters for both the real (five parameters) and complex (seven) scalar dark matter models obtained by combining Planck data on the cosmic microwave background, direct detection limits from LUX, and indirect detection limits from the Fermi Large Area Telescope. We find that for real scalars indirect dark matter searches disfavour a dark matter particle mass below 100 GeV. For the complex scalar dark matter particle current data have a limited impact due to the presence of operators that lead to p-wave annihilation, and also do not contribute to the spin-independent scattering cross- section. Although current data are not informative enough to strongly constrain the theory parameter space, we demonstrate the power of our formalism to reconstruct the theoretical parameters compatible with an actual dark matter detection, by assuming that the excess of gamma rays observed by the Fermi Large Area Telescope towards the Galactic centre is entirely due to dark matter annihilations. Please note that the excess can very well be due to astrophysical sources such as millisecond pulsars. We find that scalar dark matter interacting via effective field theory operators can in principle explain the Galactic centre excess, but that such interpretation is in strong tension with the non-detection of gamma rays from dwarf galaxies in the real scalar case. In the complex scalar case there is enough freedom to relieve the tension.

Highlights

We present global fits of an effective field theory description of real, and complex scalar dark matter candidates
We derive constraints on the free model parameters for both the real and complex scalar dark matter models obtained by combining Planck data on the cosmic microwave background, direct detection limits from LUX, and indirect detection limits from the Fermi Large Area Telescope
Current data are not informative enough to strongly constrain the theory parameter space, we demonstrate the power of our formalism to reconstruct the theoretical parameters compatible with an actual dark matter detection, by assuming that the excess of gamma rays observed by the Fermi Large Area Telescope towards the Galactic centre is entirely due to dark matter annihilations

Summary

Introduction

We present the first global analysis of all relevant EFT operators simultaneously in light of the latest constraints from indirect and direct searches for DM. [18] in several respects: we perform a more thorough statistical analysis that addresses the dependence on priors, and we perform a comparison between profile likelihood and posterior distributions; we include the contribution from DM-gluon operators that was previously neglected while being potentially sizeable; we make use of the latest data from the Fermi Large Area Telescope (Fermi -LAT); and we consider the effect of DM annihilation on the cosmic microwave background (CMB) anisotropies measured by Planck. We work in the limit in which the particles mediating the interactions between the DM, quarks, and gluons are heavy compared to the energies of interest. Where the coefficients λi have dimensions of inverse mass to the appropriate power such that the over-all dimension of L remains four and the Oi are a set of operators consisting of a DM bilinear contracted with a gauge invariant combination of quark and/or gluon fields

Methods

Results

Conclusion