Abstract
Results of a search for new physics in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 139 fb$^{-1}$ at a center-of-mass energy of 13 TeV collected in the period 2015-2018 with the ATLAS detector at the Large Hadron Collider. Compared to previous publications, in addition to an increase of almost a factor of four in the data size, the analysis implements a number of improvements in the signal selection and the background determination leading to enhanced sensitivity. Events are required to have at least one jet with transverse momentum above 150 GeV and no reconstructed leptons ($e$, $\mu$ or $\tau$) or photons. Several signal regions are considered with increasing requirements on the missing transverse momentum starting at 200 GeV. Overall agreement is observed between the number of events in data and the Standard Model predictions. Model-independent 95 % confidence-level limits on visible cross sections for new processes are obtained in the range between 736 fb and 0.3 fb with increasing missing transverse momentum. Results are also translated into improved exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, supersymmetric particles in several compressed scenarios, axion-like particles, and new scalar particles in dark-energy-inspired models. In addition, the data are translated into bounds on the invisible branching ratio of the Higgs boson.
Highlights
This paper presents the results of a new search for new phenomena in events containing an energetic jet and large missing transverse momentum pmT iss ipnffiffi proton-proton collisions at a center-of-mass energy s 1⁄4 13 TeV recorded by the ATLAS detector at the Large Hadron Collider (LHC)
This signature has been extensively studied at the LHC in the context of searches for large extra spatial dimensions (LED), supersymmetry (SUSY), weakly interacting massive particles (WIMPs) as candidates for dark matter (DM) [1,2,3,4,5], and signals from models inspired by dark energy (DE) with new scalar particles in the final state [6]
The EvtGen v1.2.0 program was used to model the decays of the bottom and charm hadrons
Summary
This paper presents the results of a new search for new phenomena in events containing an energetic jet and large missing transverse momentum pmT iss (with magnitude EmT iss) ipnffiffi proton-proton collisions at a center-of-mass energy s 1⁄4 13 TeV recorded by the ATLAS detector at the Large Hadron Collider (LHC). A monojet final state has been considered a golden channel for the discovery of WIMPs at colliders In this case, the WIMP pair is produced in association with a jet of particles from initial-state radiation, leading to the signature of a jet and missing transverse momentum [see Fig. 1(a)]. For the model relevant for this case, the new scalar particle is stable and is produced in pairs, leaving the experiment undetected When they are produced in association with an energetic gluon, it leads to a monojet final-state topology [see Fig. 1(c)].
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