ATLAS reports an 8+ sigma excess in ttbar production near threshold, consistent with NRQCD quasi-bound states and measuring 9.3 pb.
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Calibration of the light-flavour jet mistagging efficiency of the $b$-tagging algorithms with $Z$+jets events using 139 $\mathrm{fb}^{-1}$ of ATLAS proton-proton collision data at $\sqrt{s} = 13$ TeV
12 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The identification of $b$-jets, referred to as $b$-tagging, is an important part of many physics analyses in the ATLAS experiment at the Large Hadron Collider and an accurate calibration of its performance is essential for high-quality physics results. This publication describes the calibration of the light-flavour jet mistagging efficiency in a data sample of proton-proton collision events at $\sqrt{s}=13$ TeV corresponding to an integrated luminosity of 139 fb$^{-1}$. The calibration is performed in a sample of $Z$ bosons produced in association with jets. Due to the low mistagging efficiency for light-flavour jets, a method which uses modified versions of the $b$-tagging algorithms referred to as flip taggers is used in this work. A fit to the jet-flavour-sensitive secondary-vertex mass is performed to extract the scale factor from data, to correct the light-flavour jet mistagging efficiency in Monte Carlo simulations, while simultaneously correcting the $b$-jet efficiency. With this procedure, uncertainties coming from the modeling of jets from heavy-flavour hadrons are considerably lower than in previous calibrations of the mistagging scale factors, where they were dominant. The scale factors obtained in this calibration are consistent with unity within uncertainties.
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hep-ex 12representative citing papers
Simultaneous measurements of b-jet tagging and c-jet mistagging efficiency scale factors for the ATLAS GN2 tagger achieve precisions below 2% and 5% respectively using 56 fb⁻¹ of 13.6 TeV ttbar data.
Top quark mass measured at 172.17 ± 1.56 GeV via unbinned maximum-likelihood fit to m(ℓ μ⁺μ⁻) in ATLAS Run 2 data using J/ψ decays.
ATLAS reports the observation of W⁺W⁻γ triboson production with 5.9σ significance and derives constraints on anomalous quartic gauge-boson couplings via effective field theory.
ATLAS reports a new measurement of the Higgs signal strength in the VBF plus photon channel with H to bb decay, obtaining 0.2 ± 0.7 using an improved neural-network-based analysis on 133 fb^{-1} of data.
The GN2 b-jet tagger is calibrated in 56 fb⁻¹ of 13.6 TeV pp data using dileptonic tt̄ events, yielding data-to-simulation scale factors of 0.9–1.3 with ~1% uncertainty in the best bins.
Fiducial cross-section for W+b-jets at 13 TeV measured as 16.6±1.9 pb, consistent with NLO QCD prediction of 16.8±2.3 pb with twice the previous precision.
Updated ATLAS search for HH → bbγγ with 308 fb⁻¹ yields observed μ_HH = 0.9^{+1.4}_{-1.1}, 95% CL limit μ_HH < 3.7, and κ_λ in [-1.6, 6.6].
No excess above Standard Model background is observed; 95% CL limits are set on couplings of the U1 vector leptoquark model for masses 1.5-3.0 TeV.
No excess observed in search for vector-like T-quarks in Ht channel; 95% CL mass limits set at 1.40 TeV (SU(2) singlet), 1.56 TeV (doublet), and 1.66 TeV (100% BR to Ht).
No significant excess observed; gauginos excluded up to 1.2 TeV in specific supersymmetric decay scenarios.