Asymmetric Dark Matter and Effective Operators

Abstract

In order to annihilate in the early Universe to levels well below the measured dark matter density, asymmetric dark matter must possess large couplings to the Standard Model. In this paper, we consider effective operators which allow asymmetric dark matter to annihilate into quarks. In addition to a bound from requiring sufficient annihilation, the energy scale of such operators can be constrained by limits from direct detection and monojet searches at colliders. We show that the allowed parameter space for these operators is highly constrained, leading to non-trivial requirements that any model of asymmetric dark matter must satisfy.

Figures (1)

• Figure 1: Constraints on the scale $\Lambda$ as a function of dark matter mass $m_\chi$ for the eight operators of Eqs. \ref{['eq:lagSS']}-\ref{['eq:lagFT']} (in order left to right and descending). Solid blue curve is the upper bound on $\Lambda$ from the requirement that the symmetric component of dark matter compose less than 10% of the measured value in the Universe (dotted blue is the value of $\Lambda$ that gives the total amount, i.e. in a thermal dark matter scenario). Solid red is the lower bound on $\Lambda$ from direct detection experiments. Dashed red is the lower bound on $\Lambda$ from Tevatron monojet searches, taken from Ref. Goodman:2010zr (see also Bai:2010ysGoodman:2010ly). Black solid line shows the lower bound from the requirement that $\Lambda > m_\chi/2\pi$. Regions above the monojet and direct detection minimum $m_\chi$ which are allowed after all constraints are shown in grey. See text for further details.