CMS-PAS-EXO-19-020

CMS-PAS-EXO-19-020
Search for resonant production of strongly-coupled dark matter in proton-proton collisions at 13 TeV
CMS Collaboration
August 2021

Abstract: The first collider search for dark matter arising from a strongly-coupled hidden sector is presented, using a data sample corresponding to 137 fb$^{-1}$ collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. The hidden sector is hypothesized to couple to the standard model (SM) via a heavy leptophobic Z' mediator. The resonant production and decay of such a mediator in proton-proton collisions would result in two "semi-visible'' jets, which contain both visible matter and invisible dark matter. This would lead to moderate missing energy aligned with one of the jets, a signature ignored by most dark matter searches. The observed dijet transverse mass spectrum is smoothly falling, as expected from the SM; no structure compatible with the signal is observed. Assuming the same couplings as the SM Z boson, mediator masses up to 3.9 TeV are excluded at 95% confidence level, depending on the other signal model parameters. To enhance the sensitivity of the search for this particular class of models, a boosted decision tree (BDT) is trained using jet substructure variables to distinguish between semi-visible jets and standard model jets from background processes. When the BDT is employed to select events with jets identified as semi-visible, the mediator mass exclusion increases to 5.1 TeV, for wider ranges of the other signal model parameters.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to JHEP. The superseded preliminary plots can be found here.

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