Abstract
A search for new resonances decaying into a pair of jets is reported using the dataset of proton-proton collisions recorded at sqrt{s} = 13 TeV with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb−1. The distribution of the invariant mass of the two leading jets is examined for local excesses above a data-derived estimate of the Standard Model background. In addition to an inclusive dijet search, events with jets identified as containing b-hadrons are examined specifically. No significant excess of events above the smoothly falling background spectra is observed. The results are used to set cross-section upper limits at 95% confidence level on a range of new physics scenarios. Model-independent limits on Gaussian-shaped signals are also reported. The analysis looking at jets containing b-hadrons benefits from improvements in the jet flavour identification at high transverse momentum, which increases its sensitivity relative to the previous analysis beyond that expected from the higher integrated luminosity.
Highlights
Background fitBumpHunter interval q *, m q* TeV q*, m q*q*, σ × 10 p-value = 0.89 mjj [TeV] Significance W* Selection 106Data Background fit BumpHunter interval W*, m = 4 TeV W* W*, m = 5 TeV W*W*, σ × 1000 p-value = 0.88 −2 mjj [TeV] (b)
Exclusion upper limits are set on the cross-section times acceptance times branching fraction into two jets of a hypothetical signal modelled as a Gaussian peak in the particle-level mjj distribution, as shown in figure 8
The current and previous expected 95% confidence level (CL) upper limits on the crosssection times branching ratio times acceptance times b-tagging efficiency are shown in figure 9 as a function of the Z mass in the dark matter (DM) benchmark model
Summary
The ATLAS detector [30] at the LHC covers nearly the entire solid angle around the collision point. It consists of an inner tracking detector surrounded by a thin superconducting solenoid, electromagnetic and hadronic calorimeters, and a muon spectrometer incorporating three large superconducting toroidal magnets. The ATLAS detector [30] at the LHC covers nearly the entire solid angle around the collision point.1 It consists of an inner tracking detector surrounded by a thin superconducting solenoid, electromagnetic and hadronic calorimeters, and a muon spectrometer incorporating three large superconducting toroidal magnets. The high-granularity silicon pixel detector covers the vertex region and typically provides four measurements per track, the first hit normally being in the insertable Blayer installed before Run 2 [31, 32]. It is followed by the silicon microstrip tracker which usually provides eight measurements per track. Selection rate from the 40 MHz bunch crossing rate to below 100 kHz, which the high-level trigger further reduces in order to record events to disk at a rate of about 1 kHz
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