[Paper Review] LHC results for dark matter from ATLAS and CMS

Atlas Collaborations|arXiv (Cornell University)|Oct 6, 2015

Dark Matter and Cosmic Phenomena3 citations

TL;DR

This paper presents direct searches for dark matter particles produced in proton-proton collisions at √s = 8 TeV using the full LHC Run-I dataset from the ATLAS and CMS experiments. No significant deviations from the Standard Model background were observed, leading to stringent exclusion limits on the dark matter production cross section across multiple final states including jets, electroweak bosons, and heavy quarks with missing transverse momentum.

ABSTRACT

The CMS and ATLAS collaborations searched for Dark Matter (DM) particles directly produced in pair. The searches are performed using the full LHC Run-I dataset recorded with the CMS and ATLAS detectors in proton-proton collisions at a center-of-mass energy of 8 TeV. Signatures considered include those yielding energetic jets and large missing transverse momentum as well as electroweak bosons and heavy flavour quarks plus missing transverse energy. No deviation from SM background expectation was found and exclusion limits on DM production cross section were set.

Motivation & Objective

• To search for direct production of dark matter particles in proton-proton collisions at the LHC.
• To investigate final states involving energetic jets, missing transverse momentum, electroweak bosons, and heavy flavour quarks.
• To set exclusion limits on the dark matter production cross section using the full Run-I dataset.
• To test the viability of dark matter models in the context of the Standard Model background expectations.

Proposed method

• Analysis of the full LHC Run-I dataset collected by the ATLAS and CMS detectors at √s = 8 TeV.
• Identification of events with large missing transverse momentum and energetic jets or vector bosons as signatures of dark matter production.
• Use of advanced reconstruction and selection techniques to suppress Standard Model backgrounds.
• Application of kinematic reconstruction and event classification to isolate potential dark matter signals.
• Comparison of observed event yields with predicted Standard Model backgrounds using statistical methods.
• Derivation of 95% confidence level exclusion limits on the dark matter production cross section across multiple final states.

Experimental results

Research questions

• RQ1 Are there observable signals of dark matter production in proton-proton collisions at 8 TeV that deviate from Standard Model expectations?
• RQ2 What are the exclusion limits on the dark matter production cross section in final states with jets and missing transverse momentum?
• RQ3 How do the results constrain models of dark matter production via pair production in association with electroweak bosons or heavy quarks?
• RQ4 To what extent do the observed data agree with the expected Standard Model backgrounds in mono-jet and mono-boson final states?

Key findings

• No significant excess of events above the Standard Model background expectations was observed in any of the analyzed final states.
• Exclusion limits were set on the dark matter production cross section at 95% confidence level across multiple final states, including jets + missing transverse momentum and vector bosons + missing energy.
• The limits are competitive with previous results and provide strong constraints on dark matter models with weakly interacting massive particles.
• The results are consistent with the absence of new physics beyond the Standard Model in the considered final states at the 8 TeV center-of-mass energy.
• The analysis demonstrates the robustness of the LHC's sensitivity to dark matter signatures using high-energy proton collisions.
• The exclusion limits are presented as a function of dark matter mass and mediator mass, enabling comparison with theoretical models.