Search for high mass dijet resonances with a new background prediction method in proton-proton collisions at s

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Received: November 10, Revised: February 29, Accepted: April 17, Published: May 8,

2019 2020 2020 2020

The CMS collaboration E-mail: [email protected] 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 √ 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, W0 and Z0 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. Keywords: Beyond Standard Model, Hadron-Hadron scattering (experiments) ArXiv ePrint: 1911.03947

Open Access, Copyright CERN, for the benefit of the CMS Collaboration. 3 Article funded by SCOAP .

https://doi.org/10.1007/JHEP05(2020)033

JHEP05(2020)033

Search for high mass dijet resonances with a new background prediction method in proton-proton √ collisions at s = 13 TeV

Contents 1

2 The CMS detector

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3 Jet reconstruction and event selection

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4 Data and simulation comparison

4

5 Background prediction methods

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6 Limits on the resonance cross section, mass, and coupling 6.1 Narrow resonances 6.2 Broad resonances

10 12 16

7 Summary

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The CMS collaboration

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1

Introduction

New particles that decay to pairs of jets and appear as dijet resonances arise in a variety of models. String resonances [1, 2] originate from the Regge excitations of quarks and gluons. Scalar diquarks [3] are predicted by a grand unified theory based on the E6 gauge symmetry group. Mass-degenerate excited quarks (q ∗ ) [4, 5] appear in quark compositeness models. Axigluons and colorons, axial-vector and vector particles, are expected in the chiral color [6, 7] and the flavor-universal coloron [7, 8] models, respectively. Color-octet scalars [9] appear in dynamical electroweak (EW) symmetry breaking models, such as technicolor. New gauge bosons (W 0 and Z 0 ) can exist with standard model (SM) l