quark currents of eqn (\[qDMd6\]) which can interfere with $Z$ exchange. So the dimension seven operators will be neglected in the following sections. However, it is interesting to first review the sensitivity to the coefficients of the operators of eqn (\[higgs\]). The dark matter interactions to $W$ and $Z$ pairs were studied in [@HR], who used $U(1)_{em} \times
SU(3)$ invariant operators such that these contact interactions have dimension five with coupling $1/\Lambda_{CHLR}$. They find that the 8 TeV LHC with luminosity 25 fb$^{-1}$ could probe $\Lambda_{CHLR} \lsim $ TeV. This constrains the coefficients of the operators of eqn (\[higgs\]) to be $ \lsim 1/({\rm TeV}m_W^2)$, which is not restrictive. For $m_\chi< m_h/2$, a more significant limit of 10 TeV$^{-3}$ arises from requiring $\Gamma(h\to \chi \overline{\chi})
\lsim \Gamma(h\to b \overline{b})$. This restriction should be reasonable[@BMM] because the Higgs is observed to decay to $b\bar{b}$.

Estimated limits from the LHC {#sec:LHC}
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Dark matter particles are invisible to the LHC detectors, so pair production of $\chi$s can be searched for in events with missing transverse energy ($\ETm)$, which can be identified by jet(s) radiated from the incident partons. The principle Standard Model background for such “monojet” searches is $Z +$ jet production, 