scholarly journals Jet energy scale and resolution measured in proton–proton collisions at $$\sqrt{s}=13$$ TeV with the ATLAS detector

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Energy Scale ◽  
Atlas Detector ◽  
Particle Flow ◽  
Proton Collision ◽  
Reconstruction Method ◽  
Proton Proton ◽  
In Situ Techniques ◽  
Systematic Uncertainties ◽  
Wide Range ◽  
Jet Energy

AbstractJet energy scale and resolution measurements with their associated uncertainties are reported for jets using 36–81 fb$$^{-1}$$ - 1 of proton–proton collision data with a centre-of-mass energy of $$\sqrt{s}=13$$ s = 13  $${\text {Te}}{\text {V}}$$ TeV collected by the ATLAS detector at the LHC. Jets are reconstructed using two different input types: topo-clusters formed from energy deposits in calorimeter cells, as well as an algorithmic combination of charged-particle tracks with those topo-clusters, referred to as the ATLAS particle-flow reconstruction method. The anti-$$k_t$$ k t jet algorithm with radius parameter $$R=0.4$$ R = 0.4 is the primary jet definition used for both jet types. This result presents new jet energy scale and resolution measurements in the high pile-up conditions of late LHC Run 2 as well as a full calibration of particle-flow jets in ATLAS. Jets are initially calibrated using a sequence of simulation-based corrections. Next, several in situ techniques are employed to correct for differences between data and simulation and to measure the resolution of jets. The systematic uncertainties in the jet energy scale for central jets ($$|\eta |<1.2$$ | η | < 1.2 ) vary from 1% for a wide range of high-$$p_{{\text {T}}}$$ p T jets ($$250<p_{{\text {T}}} <2000~{\text {Ge}}{\text {V}}$$ 250 < p T < 2000 GeV ), to 5% at very low $$p_{{\text {T}}}$$ p T ($$20~{\text {Ge}}{\text {V}}$$ 20 GeV ) and 3.5% at very high $$p_{{\text {T}}}$$ p T ($$>2.5~{\text {Te}}{\text {V}}$$ > 2.5 TeV ). The relative jet energy resolution is measured and ranges from ($$24 \pm 1.5$$ 24 ± 1.5 )% at 20 $${\text {Ge}}{\text {V}}$$ GeV to ($$6 \pm 0.5$$ 6 ± 0.5 )% at 300 $${\text {Ge}}{\text {V}}$$ GeV .

scholarly journals Determination of jet calibration and energy resolution in proton–proton collisions at $$\sqrt{s} = 8~\hbox {TeV}$$ using the ATLAS detector

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
M. Aaboud ◽  
◽  
G. Aad ◽  
B. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Energy Resolution ◽  
Energy Scale ◽  
Atlas Detector ◽  
Residual Effects ◽  
Proton Proton ◽  
Proton Collisions ◽  
Calibration Scheme ◽  
Jet Energy ◽  
Proton Proton Collisions

AbstractThe jet energy scale, jet energy resolution, and their systematic uncertainties are measured for jets reconstructed with the ATLAS detector in 2012 using proton–proton data produced at a centre-of-mass energy of 8 TeV with an integrated luminosity of $$20 \, \hbox {fb}^{-1}$$ 20 fb - 1 . Jets are reconstructed from clusters of energy depositions in the ATLAS calorimeters using the anti-$$k_t$$ k t algorithm. A jet calibration scheme is applied in multiple steps, each addressing specific effects including mitigation of contributions from additional proton–proton collisions, loss of energy in dead material, calorimeter non-compensation, angular biases and other global jet effects. The final calibration step uses several in situ techniques and corrects for residual effects not captured by the initial calibration. These analyses measure both the jet energy scale and resolution by exploiting the transverse momentum balance in $$\gamma $$ γ  + jet, Z + jet, dijet, and multijet events. A statistical combination of these measurements is performed. In the central detector region, the derived calibration has a precision better than 1% for jets with transverse momentum $$150 \, \hbox {GeV} < p_{{\mathrm {T}}}<$$ 150 GeV < p T < 1500 GeV, and the relative energy resolution is $$(8.4\pm 0.6)\%$$ ( 8.4 ± 0.6 ) % for $$p_{{\mathrm {T}}}= 100 \, \hbox {GeV}$$ p T = 100 GeV and $$(23\pm 2)\%$$ ( 23 ± 2 ) % for $$p_{{\mathrm {T}}}= 20 \, \hbox {GeV}$$ p T = 20 GeV . The calibration scheme for jets with radius parameter $$R=1.0$$ R = 1.0 , for which jets receive a dedicated calibration of the jet mass, is also discussed.

scholarly journals Jet energy calibration at the LHC

2015 ◽  
Vol 30 (31) ◽  
pp. 1546002 ◽  
Author(s):  
Ariel Schwartzman
Keyword(s):  
Monte Carlo ◽  
Hadron Collider ◽  
High Energy ◽  
Energy Scale ◽  
Energy Calibration ◽  
Proton Proton ◽  
Systematic Uncertainties ◽  
Calibration Uncertainty ◽  
Central Detector ◽  
Jet Energy

Jets are one of the most prominent physics signatures of high energy proton–proton (p–p) collisions at the Large Hadron Collider (LHC). They are key physics objects for precision measurements and searches for new phenomena. This review provides an overview of the reconstruction and calibration of jets at the LHC during its first Run. ATLAS and CMS developed different approaches for the reconstruction of jets, but use similar methods for the energy calibration. ATLAS reconstructs jets utilizing input signals from their calorimeters and use charged particle tracks to refine their energy measurement and suppress the effects of multiple p–p interactions (pileup). CMS, instead, combines calorimeter and tracking information to build jets from particle flow objects. Jets are calibrated using Monte Carlo (MC) simulations and a residual in situ calibration derived from collision data is applied to correct for the differences in jet response between data and Monte Carlo. Large samples of dijet, [Formula: see text]+jets, and [Formula: see text]+events at the LHC allowed the calibration of jets with high precision, leading to very small systematic uncertainties. Both ATLAS and CMS achieved a jet energy calibration uncertainty of about 1% in the central detector region and for jets with transverse momentum [Formula: see text]. At low jet [Formula: see text], the jet energy calibration uncertainty is less than 4%, with dominant contributions from pileup, differences in energy scale between quark and gluon jets, and jet flavor composition.

scholarly journals Identification of boosted Higgs bosons decaying into b-quark pairs with the ATLAS detector at 13 $$\text {TeV}$$

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Top Quark ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Higgs Bosons ◽  
Proton Collision ◽  
Jet Substructure ◽  
Proton Proton ◽  
Quark Pairs ◽  
Systematic Uncertainties ◽  
B Quark

Abstract This paper describes a study of techniques for identifying Higgs bosons at high transverse momenta decaying into bottom-quark pairs, $$H \rightarrow b\bar{b}$$H→bb¯, for proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy $$\sqrt{s}=13$$s=13 $$\text {TeV}$$TeV. These decays are reconstructed from calorimeter jets found with the anti-$$k_{t}$$kt$$R = 1.0$$R=1.0 jet algorithm. To tag Higgs bosons, a combination of requirements is used: b-tagging of $$R = 0.2$$R=0.2 track-jets matched to the large-R calorimeter jet, and requirements on the jet mass and other jet substructure variables. The Higgs boson tagging efficiency and corresponding multijet and hadronic top-quark background rejections are evaluated using Monte Carlo simulation. Several benchmark tagging selections are defined for different signal efficiency targets. The modelling of the relevant input distributions used to tag Higgs bosons is studied in 36 fb$$^{-1}$$-1 of data collected in 2015 and 2016 using $$g\rightarrow b\bar{b}$$g→bb¯ and $$Z(\rightarrow b\bar{b})\gamma $$Z(→bb¯)γ event selections in data. Both processes are found to be well modelled within the statistical and systematic uncertainties.

scholarly journals Measurements of inclusive and differential cross-sections of combined $$ t\overline{t}\gamma $$ and tWγ production in the eμ channel at 13 TeV with the ATLAS detector

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Theoretical Calculations ◽  
Top Quarks ◽  
Atlas Detector ◽  
Proton Collision ◽  
Differential Cross Sections ◽  
Proton Proton ◽  
Fiducial Volume ◽  
Proton Proton Collision

Abstract Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb−1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be $$ {39.6}_{-2.3}^{+2.7} $$ 39.6 − 2.3 + 2.7 fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and angular separations between the two leptons in the event. All measurements are in agreement with the predictions from the Standard Model.

scholarly journals Measurement of cross sections and couplings of the Higgs boson in fermionic decay modes with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02119
Author(s):  
Liaoshan Shi
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
The Cross

In this report, we present the latest ATLAS results on the measurement of the cross sections and couplings of the Higgs boson in the fermionic decay modes, H → μ+μ-, H → τ+τ- and H → bb. The searches are performed with proton-proton collision data delivered by the Large Hadron Collider during Run 1 and the first two years of Run 2 at √s = 7, 8 and 13 TeV.

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