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A measurement of soft-drop jet observables in $pp$ collisions with the ATLAS detector at $\sqrt{s} = 13$ TeV

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.D 101 (2020) 052007, 2020.
Inspire Record 1772062 DOI 10.17182/hepdata.92073

Jet substructure quantities are measured using jets groomed with the soft-drop grooming procedure in dijet events from 32.9 fb$^{-1}$ of $pp$ collisions collected with the ATLAS detector at $\sqrt{s} = 13$ TeV. These observables are sensitive to a wide range of QCD phenomena. Some observables, such as the jet mass and opening angle between the two subjets which pass the soft-drop condition, can be described by a high-order (resummed) series in the strong coupling constant $\alpha_S$. Other observables, such as the momentum sharing between the two subjets, are nearly independent of $\alpha_S$. These observables can be constructed using all interacting particles or using only charged particles reconstructed in the inner tracking detectors. Track-based versions of these observables are not collinear safe, but are measured more precisely, and universal non-perturbative functions can absorb the collinear singularities. The unfolded data are directly compared with QCD calculations and hadron-level Monte Carlo simulations. The measurements are performed in different pseudorapidity regions, which are then used to extract quark and gluon jet shapes using the predicted quark and gluon fractions in each region. All of the parton shower and analytical calculations provide an excellent description of the data in most regions of phase space.

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Data from Fig 6a. The unfolded all-particle $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$ > 300 GeV, after the soft drop algorithm is applied for $\beta$ = 0, in data. All uncertainties described in the text are shown on the data. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

Data from Fig 6a. The unfolded all-particle $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$ > 300 GeV, after the soft drop algorithm is applied for $\beta$ = 0, in data. All uncertainties described in the text are shown on the data. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

Data from Fig 6b. The unfolded charged-particle $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$ > 300 GeV, after the soft drop algorithm is applied for $\beta$ = 0, in data. All uncertainties described in the text are shown on the data. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

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Version 2
A measurement of the soft-drop jet mass in pp collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.Lett. 121 (2018) 092001, 2018.
Inspire Record 1637587 DOI 10.17182/hepdata.79953

Jet substructure observables have significantly extended the search program for physics beyond the Standard Model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross-section is measured as a function of log$_{10}\rho^2$, where $\rho$ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb$^{-1}$ of $\sqrt{s} = 13$ TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

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Data from Fig 3a. The unfolded $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$(lead) > 600 GeV, after the soft drop algorithm is applied for $\beta$ = 0, in data. All uncertainties described in the text are shown on the data; the uncertainties from the calculations are shown on each one. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

Data from Fig 3a. The unfolded $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$(lead) > 600 GeV, after the soft drop algorithm is applied for $\beta$ = 0, in data. All uncertainties described in the text are shown on the data; the uncertainties from the calculations are shown on each one. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

Data from Fig 3b. The unfolded $log_{10}(\rho^2)$ distribution for anti-kt R=0.8 jets with $p_T$(lead) > 600 GeV, after the soft drop algorithm is applied for $\beta$ = 1, in data. All uncertainties described in the text are shown on the data; the uncertainties from the calculations are shown on each one. The distributions are normalized to the integrated cross section, $\sigma$(resum), measured in the resummation region, $-3.7 < log_{10}(\rho^2) < -1.7$.

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Measurements of observables sensitive to colour reconnection in $t\bar{t}$ events with the ATLAS detector at $\sqrt{s}=13$ TeV

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, D.C. ; et al.
Eur.Phys.J.C 83 (2023) 518, 2023.
Inspire Record 2152933 DOI 10.17182/hepdata.135459

A measurement of observables sensitive to effects of colour reconnection in top-quark pair-production events is presented using 139 fb$^{-1}$ of 13$\,$TeV proton-proton collision data collected by the ATLAS detector at the LHC. Events are selected by requiring exactly one isolated electron and one isolated muon with opposite charge and two or three jets, where exactly two jets are required to be $b$-tagged. For the selected events, measurements are presented for the charged-particle multiplicity, the scalar sum of the transverse momenta of the charged particles, and the same scalar sum in bins of charged-particle multiplicity. These observables are unfolded to the stable-particle level, thereby correcting for migration effects due to finite detector resolution, acceptance and efficiency effects. The particle-level measurements are compared with different colour reconnection models in Monte Carlo generators. These measurements disfavour some of the colour reconnection models and provide inputs to future optimisation of the parameters in Monte Carlo generators.

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Naming convention for the observables at different levels of the analysis. At the background-subtracted level the contributions of tracks from pile-up collisions and tracks from secondary vertices are subtracted. At the corrected level the tracking-efficiency correction (TEC) is applied. The observables at particle level are the analysis results.

The $\chi^2$ and NDF for measured normalised differential cross-sections obtained by comparing the different predictions with the unfolded data. Global($n_\text{ch},\Sigma_{n_{\text{ch}}} p_{\text{T}}$) denotes the scenario in which the covariance matrix is built including the correlations of systematic uncertainties between the two observables $n_{\text{ch}}$ and $\Sigma_{n_{\text{ch}}} p_{\text{T}}$

Normalised differential cross-section as a function of $n_\text{ch}$.

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Searches for scalar leptoquarks and differential cross-section measurements in dilepton-dijet events in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV with the ATLAS experiment

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J.C 79 (2019) 733, 2019.
Inspire Record 1718132 DOI 10.17182/hepdata.83968

Searches for scalar leptoquarks pair-produced in proton-proton collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider are performed by the ATLAS experiment. A data set corresponding to an integrated luminosity of 36.1 fb$^{-1}$ is used. Final states containing two electrons or two muons and two or more jets are studied, as are states with one electron or muon, missing transverse momentum and two or more jets. No statistically significant excess above the Standard Model expectation is observed. The observed and expected lower limits on the leptoquark mass at 95% confidence level extend up to 1.29 TeV and 1.23 TeV for first- and second-generation leptoquarks, respectively, as postulated in the minimal Buchm\"uller-R\"uckl-Wyler model, assuming a branching ratio into a charged lepton and a quark of 50%. In addition, measurements of particle-level fiducial and differential cross sections are presented for the $Z\rightarrow ee$, $Z\rightarrow\mu\mu$ and $t\bar{t}$ processes in several regions related to the search control regions. Predictions from a range of generators are compared with the measurements, and good agreement is seen for many of the observables. However, the predictions for the $Z\rightarrow\ell\ell$ measurements in observables sensitive to jet energies disagree with the data.

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Inclusive cross-section and uncertainty from each source, for the dominant process in the each measurement region.

Differential cross-section and uncertainty from each source, as a function of leading $p_{T}^j$ for the dominant process in the $eejj$ measurement region.

Differential cross-section and uncertainty from each source, as a function of leading $p_{T}^j$ for the dominant process in the $\mu\mu jj$ measurement region.

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Version 2
Measurement of differential cross-sections of a single top quark produced in association with a $W$ boson at $\sqrt{s}=13$ TeV with ATLAS

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J.C 78 (2018) 186, 2018.
Inspire Record 1641076 DOI 10.17182/hepdata.81944

The differential cross-section for the production of a $W$ boson in association with a top quark is measured for several particle-level observables. The measurements are performed using 36.1 fb$^{-1}$ of $pp$ collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase space defined by the presence of two charged leptons and exactly one jet matched to a $b$-hadron, and are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators.

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Absolute cross-sections differential in E(b). Uncertainties are signed to show correlations.

Absolute cross-sections differential in m(l1b). Uncertainties are signed to show correlations.

Absolute cross-sections differential in m(l2b). Uncertainties are signed to show correlations.

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Measurement of the Lund jet plane using charged particles in 13 TeV proton-proton collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.Lett. 124 (2020) 222002, 2020.
Inspire Record 1790256 DOI 10.17182/hepdata.93183

The prevalence of hadronic jets at the LHC requires that a deep understanding of jet formation and structure is achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a recent proposal to factorize physical effects, this Letter presents a double-differential cross-section measurement of the Lund jet plane using 139 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data collected with the ATLAS detector using jets with transverse momentum above 675 GeV. The measurement uses charged particles to achieve a fine angular resolution and is corrected for acceptance and detector effects. Several parton shower Monte Carlo models are compared with the data. No single model is found to be in agreement with the measured data across the entire plane.

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Normalized differential cross-section of the Lund jet plane. The first systematic uncertainty is detector systematics, the second is background systematic uncertainties

Normalized differential cross-section of the Lund jet plane. The first systematic uncertainty is detector systematics, the second is background systematic uncertainties. The data is presented as a 1D distribution, for use in MC tuning.

Normalized differential cross-section of the Lund jet plane. The first systematic uncertainty is detector systematics, the second is background systematic uncertainties. The data is presented as a 1D distribution, for a single vertical slice of the Lund jet plane between 0.00 < ln(R/#DeltaR) < 0.33.

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Measurement of isolated-photon plus two-jet production in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
JHEP 03 (2020) 179, 2020.
Inspire Record 1772071 DOI 10.17182/hepdata.101751

The dynamics of isolated-photon plus two-jet production in $pp$ collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, $\gamma+jet+jet$. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from SHERPA and PYTHIA as well as the next-to-leading-order QCD predictions from SHERPA are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data.

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Measured cross sections for isolated-photon plus two-jet production as functions of $E_{\mathrm{T}}^{\gamma}$ for the total phase-space. The predictions from Sherpa NLO are also included.

Measured cross sections for isolated-photon plus two-jet production as functions of $p_{\mathrm{T}}^{\textrm{jet}}$ for the total phase-space. The predictions from Sherpa NLO are also included.

Measured cross sections for isolated-photon plus two-jet production as functions of $|y^{\textrm{jet}}|$ for the total phase-space. The predictions from Sherpa NLO are also included.

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Observation of electroweak $W^{\pm}Z$ boson pair production in association with two jets in $pp$ collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett.B 793 (2019) 469-492, 2019.
Inspire Record 1711223 DOI 10.17182/hepdata.83785

An observation of electroweak $W^{\pm}Z$ production in association with two jets in proton-proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of $\sqrt{s} =$ 13 TeV are used, corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of $W^{\pm}Z$ bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section for electroweak production including interference effects is measured to be $\sigma_{WZjj\mathrm{-EW}} = 0.57 \; ^{+ 0.14} _{- 0.13} \,(\mathrm{stat.}) \; ^{+ 0.07} _{- 0.06} \,(\mathrm{syst.}) \; \mathrm{fb}$. Total and differential fiducial cross-sections of the sum of $W^\pm Z jj$ electroweak and strong productions for several kinematic observables are also measured.

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Fiducial cross section of the electroweak $W^{\pm}Z$ boson pair production in association with two jets. The first systematic uncertainty is experimental, the second is the theory modelling and interference systematics and the third one is the luminosity uncertainty.

Fiducial cross section of the $W^{\pm}Z$ boson pair production in association with two jets. The first systematic uncertainty is experimental, the second is the theory modelling and interference systematics and the third one is the luminosity uncertainty.

Numbers of observed and expected events in the $W^{\pm}Zjj$ signal region and in the three control regions, before the fit. The expected number of $WZjj-EW$ events from $SHERPA$ and the estimated number of background events from the other processes are shown. The sum of the background containing misidentified leptons is labelled "Misid. leptons". The total uncertainties are quoted.

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Version 2
Measurements of top-quark pair differential cross-sections in the lepton+jets channel in $pp$ collisions at $\sqrt{s}$=13 TeV using the ATLAS detector

The ATLAS collaboration Aaboud, M. ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 11 (2017) 191, 2017.
Inspire Record 1614149 DOI 10.17182/hepdata.80041

Measurements of differential cross-sections of top-quark pair production in fiducial phase-spaces are presented as a function of top-quark and $t\bar{t}$ system kinematic observables in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$=13 TeV. The data set corresponds to an integrated luminosity of $3.2$ fb${}^{-1}$, recorded in 2015 with the ATLAS detector at the CERN Large Hadron Collider. Events with exactly one electron or muon and at least two jets in the final state are used for the measurement. Two separate selections are applied that each focus on different top-quark momentum regions, referred to as resolved and boosted topologies of the $t\bar{t}$ final state. The measured spectra are corrected for detector effects and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ and $p$-values.

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Table of systematic uncertainties for the absolute differential cross-section at particle level for the top quark transverse momentum in the resolved regime. Note that the values shown here are obtained by propagating the individual uncertainties to the measured cross-sections, while the covariance matrices are evaluated using pseudo-experiments as described in the text.

Table of systematic uncertainties for the absolute differential cross-section at particle level for the top quark transverse momentum in the resolved regime. Note that the values shown here are obtained by propagating the individual uncertainties to the measured cross-sections, while the covariance matrices are evaluated using pseudo-experiments as described in the text.

Table of systematic uncertainties for the relative differential cross-section at particle level for the top quark transverse momentum in the resolved regime. Note that the values shown here are obtained by propagating the individual uncertainties to the measured cross-sections, while the covariance matrices are evaluated using pseudo-experiments as described in the text.

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Version 2
Measurement of jet substructure observables in $\mathrm{t\overline{t}}$ events from proton-proton collisions at $\sqrt{s} =$ 13TeV

The CMS collaboration Sirunyan, A. M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 98 (2018) 092014, 2018.
Inspire Record 1690148 DOI 10.17182/hepdata.84716

A measurement of jet substructure observables is presented using \ttbar events in the lepton+jets channel from proton-proton collisions at $\sqrt{s}=$ 13 TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Multiple jet substructure observables are measured for jets identified as bottom, light-quark, and gluon jets, as well as for inclusive jets (no flavor information). The results are unfolded to the particle level and compared to next-to-leading-order predictions from POWHEG interfaced with the parton shower generators PYTHIA 8 and HERWIG 7, as well as from SHERPA 2 and DIRE2. A value of the strong coupling at the Z boson mass, $\alpha_S(m_\mathrm{Z}) = $ 0.115$^{+0.015}_{-0.013}$, is extracted from the substructure data at leading-order plus leading-log accuracy.

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Distribution of $\lambda_{0}^{0}$ (N) reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

Distribution of $\lambda_{0}^{0}$ (N) reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

Distribution of $\lambda_{0}^{2}$ ($p_{T}^{d,*})$ reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

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