Abstract
A search for narrow and broad resonances with masses greater than 1.8 TeV decaying to a pair of jets is presented. The search uses proton-proton collision data at sqrt{s} = 13 TeV collected at the LHC, corresponding to an integrated luminosity of 137 fb−1. The background arising from standard model processes is predicted with the fit method used in previous publications and with a new method. The dijet invariant mass spectrum is well described by both data-driven methods, and no significant evidence for the production of new particles is observed. Model independent upper limits are reported on the production cross sections of narrow resonances, and broad resonances with widths up to 55% of the resonance mass. Limits are presented on the masses of narrow resonances from various models: string resonances, scalar diquarks, axigluons, colorons, excited quarks, color-octet scalars, W′ and Z′ bosons, Randall-Sundrum gravitons, and dark matter mediators. The limits on narrow resonances are improved by 200 to 800 GeV relative to those reported in previous CMS dijet resonance searches. The limits on dark matter mediators are presented as a function of the resonance mass and width, and on the associated coupling strength as a function of the mediator mass. These limits exclude at 95% confidence level a dark matter mediator with a mass of 1.8 TeV and width 1% of its mass or higher, up to one with a mass of 4.8 TeV and a width 45% of its mass or higher.
Highlights
We inspect the characteristics of the 23 events with mjj > 7 TeV, to determine if they have the two-jet topology typical of the quantum chromodynamics (QCD) background and to check for the presence of detector and reconstruction pathologies, and we find the one unusual event, shown in
The possibility that this event originates from a resonance decaying to a pair of dijet resonances has been recently explored in a phenomenology paper [49]
The ratio method is a data-driven prediction of the QCD background in the signal region (SR), obtained by multiplying the data in CRhigh by a mass-dependent transfer factor determined from the simulated angular distribution of QCD dijet production
Summary
A detailed description of the CMS detector and its coordinate system, including definitions of the azimuthal angle φ and pseudorapidity η, is given in ref. [35]. A detailed description of the CMS detector and its coordinate system, including definitions of the azimuthal angle φ and pseudorapidity η, is given in ref. The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter providing an axial magnetic field of 3.8 T. Within the solenoid volume are located the silicon pixel and strip tracker (|η| < 2.4), and the barrel and endcap calorimeters (|η| < 3.0), where these latter detectors consist of a lead tungstate crystal electromagnetic calorimeter and a brass and scintillator hadron calorimeter. An iron and quartz-fiber hadron calorimeter is located in the forward region (3.0 < |η| < 5.0), outside the solenoid volume. The muon detection system covers |η| < 2.4 with up to four layers of gas-ionization chambers installed outside the solenoid and embedded in the layers of the steel flux-return yoke
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