Abstract
A search is presented for dark matter in proton-proton collisions at a center-of-mass energy of s=13 TeV using events with at least one high transverse momentum (pT) muon, at least one high-pT jet, and large missing transverse momentum. The data were collected with the CMS detector at the CERN LHC in 2016 and 2017, and correspond to an integrated luminosity of 77.4 fb−1. In the examined scenario, a pair of scalar leptoquarks is assumed to be produced. One leptoquark decays to a muon and a jet while the other decays to dark matter and low-pT standard model particles. The signature for signal events would be significant missing transverse momentum from the dark matter in conjunction with a peak at the leptoquark mass in the invariant mass distribution of the highest pT muon and jet. The data are observed to be consistent with the background predicted by the standard model. For the first benchmark scenario considered, dark matter masses up to 500 GeV are excluded for leptoquark masses mLQ≈1400 GeV, and up to 300 GeV for mLQ≈1500 GeV. For the second benchmark scenario, dark matter masses up to 600 GeV are excluded for mLQ≈1400 GeV.
Highlights
Dark matter (DM) has been a subject of intense interest for decades
It is assumed that dark matter is produced through the production of a leptoquark pair, with one leptoquark decaying to a muon and a jet, and the other to dark matter and low-pT standard model particles
The analysis is performed by searching for a peak in the leptoquark candidate invariant mass mμj distribution formed from the highest pT muon and jet in an event, with the requirement of significant missing transverse momentum, as is expected from the presence of dark matter
Summary
Dark matter (DM) has been a subject of intense interest for decades. Extensive astrophysical evidence for DM exists [1,2,3], such as from observations of the dynamics of galaxy clusters and measurements of anisotropies in the cosmic microwave background. [23] for the upper component of the LQ doublet, and taking mDM = 300 GeV as a representative value, the lower limit on a secondgeneration LQ is reduced to 1340 GeV for B = 0.5 and to 960 GeV for B = 0.1 In this analysis, the final state consists of a high-pT muon and a high-pT jet from the decay of the on-shell LQ, pmT iss from the DM particles, and low-pT SM objects from the decay of the offshell LQ. The principal SM backgrounds in this search arise from events with a W boson and jets (W +jets) or with a top quark-antiquark (tt) pair: in both cases, the leptonic decay of a W boson can yield a high-pT muon and neutrino, where the neutrino can lead to significant pmT iss. Events with Z +jets production can enter the background if one of the leptons in Z → μ+μ− decays is not reconstructed or lies outside the acceptance of the detector, leading to pmT iss, or if pmT iss arises because of misreconstructed jet pT
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