Characterizing dark matter at the LHC in Drell-Yan events

Abstract

Spectral features in LHC dileptonic events may signal radiative corrections coming from new degrees of freedom, notably dark matter and mediators. Using simplified models, and under a set of simplifying assumptions, we show how these features can reveal the fundamental properties of the dark sector, such as self-conjugation, spin and mass of dark matter, and the quantum numbers of the mediator. Distributions of both the invariant mass m ll and the Collins-Soper scattering angle cos θ CS are studied to pinpoint these properties. We derive constraints on the models from LHC measurements of m ll and cos θ CS , which are competitive with direct detection and jets þ MET searches. We find that in certain scenarios the cos θ CS spectrum provides the strongest bounds, underlining the importance of scattering angle measurements for nonresonant new physics.

Hunting leptoquarks in monolepton searches

“…While the precision obtainable in Drell-Yan (dilepton and monolepton) measurements is exploited in this work to constrain leptoquarks, it has also been used to constrain the running of electroweak couplings [23][24][25], dark matter [26][27][28], electroweak precision observables [29], and new Z 0 bosons [30,31]. Since several new physics models predict deviations from the SM Drell-Yan prediction one may need to use other LHC observables or complementary measurements like APV to distinguish among those models.…”

“…[38] does not provide UFO files, we generate spectra analytically. Next, as done in [28], all our spectra are then rescaled by a global factor that accounts for the lepton reconstruction efficiency, so that our background spectra match the irreducible background taken from ATLAS (and extracted via HEPData [41]). The net signal and background events are obtained by adding the reducible background extracted from [34,35] to our generated events.…”

The radiation valley and exotic resonances in Wγ production at the LHC

“…The role of cos θ CS -While we have focused on ∆y for the purposes of the RV cut, the cos θ CS variable is still a useful one. Should a W γ resonance be found, the cos θ CS angle can also be used to discriminate the spin of NP signals [67,68] (Fig. 7).…”

Simplified Dark Matter Models

“…Interestingly, this signature with two high-p T jets leads to constraints stronger then the mono-jet one on a large portion of parameter space, except for the compressed region |m med − m χ | m med [69]. An interesting phenomenology arises in the case in which the t-channel mediators couple DM to both quarks and leptons, as in [81,82]. Radiative corrections in this model strongly alter the spectrum of the Drell-Yan process q q → + − .…”