particle content of the EFT for $\chi$ at the LHC should be $\chi$, plus all relevant particles of the SM, which I take to be the partons, the Higgs, and the $Z$.

The operators should be SM gauge invariant, to profit from our knowledge of the SM gauge sector. They are of dimension $>$ 4, and should attach a $\chi \overline{\chi}$ pair to partons, to the Higgs, or to the $Z$. The quark operators are taken generation diagonal; flavour-changing operators were considered in [@CK11]. The quarks are chiral because the operators are SM gauge invariant, and also because opposite chiralities do not interfere at the LHC. The dark matter currents are taken in a vector, axial vector, etc basis because these do not interfere in direct detection, nor at the LHC in the limit where the $\chi$ mass is neglected, as done here.

I focus on operators of lowest dimension, that is six and seven. This is an arbitrary simplification, because $\Lambda \sim$ TeV, which is the energy scale probed at the LHC. The contact interactions considered here therefore do not provide a “model-independent” parametrisation of the interactions of $\chi$ with the SM. This problem is left for a later 