Search for the production of dark matter in association with top-quark pairs in the single-lepton final state in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This study searches for dark matter produced with top-quark pairs in proton-proton collisions at 8 TeV, using CMS data, and sets limits on interaction scales and scattering cross sections due to no observed excess.

Contribution

It provides the first limits on dark matter production with top-quark pairs at 8 TeV and interprets results in terms of interaction scales and scattering cross sections.

Findings

No excess events above Standard Model expectations.

Set lower limits on scalar contact interaction scale.

Derived constraints on dark matter-nucleon scattering cross sections.

Abstract

A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of sqrt(s) = 8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 inverse femtobarns. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.