Direct detection and LHC constraints on a t-channel simplified model of Majorana dark matter at one loop

Abstract

An interesting class of models posits that the dark matter is a Majorana fermion which interacts with a quark together with a colored scalar mediator. Such a theory can be tested in direct detection experiments, through dark matter scattering with heavy nuclei, and at the LHC, via jets and missing energy signatures. Motivated by the fact that such theories have spin-independent interactions that vanish at tree level, we examine them at one loop (along with RGE improvement to resum large logs), and find that despite its occurrence at a higher order of perturbation theory, the spin-independent scattering searches typically impose the strongest constraints on the model parameter space. We further analyze the corresponding LHC constraints at one loop and find that it is important to take them into account when interpreting the implications of searches for jets plus missing momentum on this class of models, thus providing the corresponding complementary information for this class of models.where the covariant derivative D µ = ∂ µ − ig s G a µ T a + Electroweak terms , describes the mediator couplings to the SM gauge bosons. Here the sums are over quark and mediator flavors where u = {u, d, s} quarks,ũ = ũ,d,s mediators, d =

Dark matter models and direct detection

“…It is important to check the loop-induced interactions, since the constraints on spin-independent DM-nucleon couplings are much stronger than on spin-dependent couplings. We refer the reader to some of the literature on matching and running down to the QCD scale [138,139,140,141,142], and as our starting point assume that C i are Wilson coefficients at the QCD scale. The next step is that quark level operators must get matched onto nucleon level operators with a similar tensor structure.…”

A universal framework for t-channel dark matter models

“…While tree-level cross sections can be negligible, if not zero, NLO corrections or loop-induced processes might set up the stage. This is the case for any considered model restriction involving Majorana or scalar dark matter [23][24][25]34,61,62], while it is more model dependent for Dirac dark matter [26]. In the following, we focus on the fermionic dark matter case.…”

Dark matter freeze out during an early cosmological period of QCD confinement

“…at leading order [21], with hadronic matrix elements f T q , and f T g defined as in references [22,23].…”