Date

Measurements of inclusive and differential fiducial cross-sections of $t\bar{t}\gamma$ production in leptonic final states at $\sqrt{s}$ = 13 TeV in ATLAS

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J.C 79 (2019) 382, 2019.
Inspire Record 1707015 DOI 10.17182/hepdata.88061

Inclusive and differential cross-sections for the production of a top-quark pair in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 36.1 fb$^{-1}$, collected by the ATLAS detector at the LHC in 2015 and 2016 at a centre-of-mass energy of 13 TeV. The measurements are performed in single-lepton and dilepton final states in a fiducial volume. Events with exactly one photon, one or two leptons, a channel-dependent minimum number of jets, and at least one $b$-jet are selected. Neural network algorithms are used to separate the signal from the backgrounds. The fiducial cross-sections are measured to be 521 $\pm$ 9(stat.) $\pm$ 41(sys.) fb and 69 $\pm$ 3(stat.) $\pm$ 4(sys.) fb for the single-lepton and dilepton channels, respectively. The differential cross-sections are measured as a function of photon transverse momentum, photon absolute pseudorapidity, and angular distance between the photon and its closest lepton in both channels, as well as azimuthal opening angle and absolute pseudorapidity difference between the two leptons in the dilepton channel. All measurements are in agreement with the theoretical predictions.

20 data tables

The measured fiducial cross section in the single lepton channel. The first uncertainty is the statistical uncertainty and the second one is the systematic uncertainty.

The measured fiducial cross section in the dilepton channel. The first uncertainty is the statistical uncertainty and the second one is the systematic uncertainty.

The measured normalized differential cross section as a function of the photon pT in the single lepton channel. The uncertainty is decomposed into five components which are the signal modelling uncertainty, the experimental uncertainty, the ttbar modelling uncertainty, the other background estimation uncertainty, and the data statistical uncertainty.

More…

Search for long-lived particles produced in $pp$ collisions at $\sqrt{s}=13$ TeV that decay into displaced hadronic jets in the ATLAS muon spectrometer

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 99 (2019) 052005, 2019.
Inspire Record 1704138 DOI 10.17182/hepdata.85748

A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. The analysis in this paper uses 36.1 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 13$ TeV recorded in 2015-2016. The search employs techniques for reconstructing vertices of long-lived particles decaying into jets in the muon spectrometer exploiting a two vertex strategy and a novel technique that requires only one vertex in association with additional activity in the detector that improves the sensitivity for longer lifetimes. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined.

122 data tables

- - - - - - - - - - - - - - - - - - - - <br/><b>Muon RoI Cluster trigger efficiency:</b> <br/><i>mPhi=100:</i> <a href="85748?version=1&table=Table1">Barrel</a> <i>mPhi=125:</i> <a href="85748?version=1&table=Table2">Barrel</a> <br/><i>mPhi=200:</i> <a href="85748?version=1&table=Table3">Barrel</a> <i>mPhi=400:</i> <a href="85748?version=1&table=Table4">Barrel</a> <br/><i>mPhi=600:</i> <a href="85748?version=1&table=Table5">Barrel</a> <i>mPhi=1000:</i> <a href="85748?version=1&table=Table6">Barrel</a> <br/><i>Stealth SUSY:</i> <a href="85748?version=1&table=Table7">Barrel</a> <br/><i>Baryogenesis nubb:</i> <a href="85748?version=1&table=Table8">Barrel</a> <i>Baryogenesis cbs:</i> <a href="85748?version=1&table=Table9">Barrel</a> <br/><i>Baryogenesis lcb:</i> <a href="85748?version=1&table=Table10">Barrel</a> <i>Baryogenesis tautaunu:</i> <a href="85748?version=1&table=Table11">Barrel</a> <br/><i>mPhi=100:</i> <a href="85748?version=1&table=Table12">Endcaps</a> <i>mPhi=125:</i> <a href="85748?version=1&table=Table13">Endcaps </a> <br/><i>mPhi=200:</i> <a href="85748?version=1&table=Table14">Endcaps</a> <i>mPhi=400:</i> <a href="85748?version=1&table=Table15">Endcaps</a> <br/><i>mPhi=600:</i> <a href="85748?version=1&table=Table16">Endcaps</a> <i>mPhi=1000:</i> <a href="85748?version=1&table=Table17">Endcaps</a> <br/><i>Stealth SUSY:</i> <a href="85748?version=1&table=Table18">Endcaps</a> <br/><i>Baryogenesis nubb:</i> <a href="85748?version=1&table=Table19">Endcaps</a> <i>Baryogenesis cbs:</i> <a href="85748?version=1&table=Table20">Endcaps</a> <br/><i>Baryogenesis lcb:</i> <a href="85748?version=1&table=Table21">Endcaps</a> <i>Baryogenesis tautaunu:</i> <a href="85748?version=1&table=Table22">Endcaps</a> <br/><b>MS vertex efficiency:</b> <br/><i>mPhi=100:</i> <a href="85748?version=1&table=Table23">Barrel</a> <i>mPhi=125:</i> <a href="85748?version=1&table=Table24">Barrel</a> <br/><i>mPhi=200:</i> <a href="85748?version=1&table=Table25">Barrel</a> <i>mPhi=400:</i> <a href="85748?version=1&table=Table26">Barrel</a> <br/><i>mPhi=600:</i> <a href="85748?version=1&table=Table27">Barrel</a> <i>mPhi=1000:</i> <a href="85748?version=1&table=Table28">Barrel</a> <br/><i>Stealth SUSY:</i> <a href="85748?version=1&table=Table29">Barrel</a> <br/><i>Baryogenesis nubb:</i> <a href="85748?version=1&table=Table30">Barrel</a> <i>Baryogenesis cbs:</i> <a href="85748?version=1&table=Table31">Barrel</a> <br/><i>Baryogenesis lcb:</i> <a href="85748?version=1&table=Table32">Barrel</a> <i>Baryogenesis tautaunu:</i> <a href="85748?version=1&table=Table33">Barrel</a> <br/><i>mPhi=100:</i> <a href="85748?version=1&table=Table34">Endcaps</a> <i>mPhi=125:</i> <a href="85748?version=1&table=Table35">Endcaps</a> <br/><i>mPhi=200:</i> <a href="85748?version=1&table=Table36">Endcaps</a> <i>mPhi=400:</i> <a href="85748?version=1&table=Table37">Endcaps</a> <br/><i>mPhi=600:</i> <a href="85748?version=1&table=Table38">Endcaps</a> <i>mPhi=1000:</i> <a href="85748?version=1&table=Table39">Endcaps</a> <br/><i>Stealth SUSY:</i> <a href="85748?version=1&table=Table40">Endcaps</a> <br/><i>Baryogenesis nubb:</i> <a href="85748?version=1&table=Table41">Endcaps</a> <i>Baryogenesis cbs:</i> <a href="85748?version=1&table=Table42">Endcaps</a> <br/><i>Baryogenesis lcb:</i> <a href="85748?version=1&table=Table43">Endcaps</a> <i>Baryogenesis tautaunu:</i> <a href="85748?version=1&table=Table44">Endcaps</a> <br/><b>Exclusion limits:</b> <br/><i>mPhi=125, mS=5:</i> <a href="85748?version=1&table=Table45">2Vx</a> <a href="85748?version=1&table=Table46">1Vx</a> <a href="85748?version=1&table=Table47">Combined</a> <br/><i>mPhi=125, mS=8:</i> <a href="85748?version=1&table=Table48">2Vx</a> <a href="85748?version=1&table=Table49">1Vx</a> <a href="85748?version=1&table=Table50">Combined</a> <br/><i>mPhi=125, mS=15:</i> <a href="85748?version=1&table=Table51">2Vx</a> <a href="85748?version=1&table=Table52">1Vx</a> <a href="85748?version=1&table=Table53">Combined</a> <br/><i>mPhi=125, mS=25:</i> <a href="85748?version=1&table=Table54">2Vx</a> <a href="85748?version=1&table=Table55">1Vx</a> <a href="85748?version=1&table=Table56">Combined</a> <br/><i>mPhi=125, mS=40:</i> <a href="85748?version=1&table=Table57">2Vx</a> <a href="85748?version=1&table=Table58">1Vx</a> <a href="85748?version=1&table=Table59">Combined</a> <br/><i>Stealth SUSY mG=250:</i> <a href="85748?version=1&table=Table60">2Vx</a> <br/><i>Stealth SUSY mG=500:</i> <a href="85748?version=1&table=Table61">2Vx</a> <a href="85748?version=1&table=Table62">1Vx</a> <a href="85748?version=1&table=Table63">Combined</a> <br/><i>Stealth SUSY mG=800:</i> <a href="85748?version=1&table=Table64">2Vx</a> <a href="85748?version=1&table=Table65">1Vx</a> <a href="85748?version=1&table=Table66">Combined</a> <br/><i>Stealth SUSY mG=1200:</i> <a href="85748?version=1&table=Table67">2Vx</a> <a href="85748?version=1&table=Table68">1Vx</a> <a href="85748?version=1&table=Table69">Combined</a> <br/><i>Stealth SUSY mG=1500:</i> <a href="85748?version=1&table=Table70">2Vx</a> <a href="85748?version=1&table=Table71">1Vx</a> <a href="85748?version=1&table=Table72">Combined</a> <br/><i>Stealth SUSY mG=2000:</i> <a href="85748?version=1&table=Table73">2Vx</a> <a href="85748?version=1&table=Table74">1Vx</a> <a href="85748?version=1&table=Table75">Combined</a> <br/><i>mPhi=100, mS=8:</i> <a href="85748?version=1&table=Table76">2Vx</a> <br/><i>mPhi=100, mS=25:</i> <a href="85748?version=1&table=Table77">2Vx</a> <br/><i>mPhi=200, mS=8:</i> <a href="85748?version=1&table=Table78">2Vx</a> <br/><i>mPhi=200, mS=25:</i> <a href="85748?version=1&table=Table79">2Vx</a> <br/><i>mPhi=200, mS=50:</i> <a href="85748?version=1&table=Table80">2Vx</a> <br/><i>mPhi=400, mS=50:</i> <a href="85748?version=1&table=Table81">2Vx</a> <br/><i>mPhi=400, mS=100:</i> <a href="85748?version=1&table=Table82">2Vx</a> <br/><i>mPhi=600, mS=50:</i> <a href="85748?version=1&table=Table83">2Vx</a> <br/><i>mPhi=600, mS=150:</i> <a href="85748?version=1&table=Table84">2Vx</a> <br/><i>mPhi=1000, mS=50:</i> <a href="85748?version=1&table=Table85">2Vx</a> <br/><i>mPhi=1000, mS=150:</i> <a href="85748?version=1&table=Table86">2Vx</a> <br/><i>mPhi=1000, mS=400:</i> <a href="85748?version=1&table=Table87">2Vx</a> <br/><i>Baryogenesis nubb, mChi=10</i> <a href="85748?version=1&table=Table88">2Vx</a> <a href="85748?version=1&table=Table89">1Vx</a> <a href="85748?version=1&table=Table90">Combined</a> <br/><i>Baryogenesis nubb, mChi=30</i> <a href="85748?version=1&table=Table91">2Vx</a> <a href="85748?version=1&table=Table92">1Vx</a> <a href="85748?version=1&table=Table93">Combined</a> <br/><i>Baryogenesis nubb, mChi=50</i> <a href="85748?version=1&table=Table94">2Vx</a> <a href="85748?version=1&table=Table95">1Vx</a> <a href="85748?version=1&table=Table96">Combined</a> <br/><i>Baryogenesis nubb, mChi=100</i> <a href="85748?version=1&table=Table97">2Vx</a> <br/><i>Baryogenesis cbs, mChi=10</i> <a href="85748?version=1&table=Table98">2Vx</a> <a href="85748?version=1&table=Table99">1Vx</a> <a href="85748?version=1&table=Table100">Combined</a> <br/><i>Baryogenesis cbs, mChi=30</i> <a href="85748?version=1&table=Table101">2Vx</a> <a href="85748?version=1&table=Table102">1Vx</a> <a href="85748?version=1&table=Table103">Combined</a> <br/><i>Baryogenesis cbs, mChi=50</i> <a href="85748?version=1&table=Table104">2Vx</a> <a href="85748?version=1&table=Table105">1Vx</a> <a href="85748?version=1&table=Table106">Combined</a> <br/><i>Baryogenesis cbs, mChi=100</i> <a href="85748?version=1&table=Table107">2Vx</a> <br/><i>Baryogenesis lcb, mChi=10</i> <a href="85748?version=1&table=Table108">2Vx</a> <a href="85748?version=1&table=Table109">1Vx</a> <a href="85748?version=1&table=Table110">Combined</a> <br/><i>Baryogenesis lcb, mChi=30</i> <a href="85748?version=1&table=Table111">2Vx</a> <a href="85748?version=1&table=Table112">1Vx</a> <a href="85748?version=1&table=Table113">Combined</a> <br/><i>Baryogenesis lcb, mChi=50</i> <a href="85748?version=1&table=Table114">2Vx</a> <a href="85748?version=1&table=Table115">1Vx</a> <a href="85748?version=1&table=Table116">Combined</a> <br/><i>Baryogenesis lcb, mChi=100</i> <a href="85748?version=1&table=Table117">2Vx</a> <br/><i>Baryogenesis tatanu, mChi=10</i> <a href="85748?version=1&table=Table118">2Vx</a> <br/><i>Baryogenesis tatanu, mChi=30</i> <a href="85748?version=1&table=Table119">2Vx</a> <br/><i>Baryogenesis tatanu, mChi=50</i> <a href="85748?version=1&table=Table120">2Vx</a> <br/><i>Baryogenesis tatanu, mChi=100</i> <a href="85748?version=1&table=Table121">2Vx</a>

Barrel Muon RoI Cluster trigger efficiencies (in %) for $m_{\Phi}=100$ GeV scalar benchmark samples. The trigger efficiency is defined as the fraction of LLPs selected by the Muon RoI Cluster trigger as a function of the LLP decay position. The trigger is efficient for hadronic decays of LLPs that occur anywhere from the outer regions of the HCal to the middle station of the MS. These efficiencies are obtained from the subset of events with only a single LLP decay in the muon spectrometer in order to ensure that the result of the trigger is due to a single burst of MS activity. The uncertainties shown are statistical only. The relative differences in efficiencies of the benchmark samples are a result of the different kinematics.

Barrel Muon RoI Cluster trigger efficiencies (in %) for $m_{\Phi}=125$ GeV scalar benchmark samples. The trigger efficiency is defined as the fraction of LLPs selected by the Muon RoI Cluster trigger as a function of the LLP decay position. The trigger is efficient for hadronic decays of LLPs that occur anywhere from the outer regions of the HCal to the middle station of the MS. These efficiencies are obtained from the subset of events with only a single LLP decay in the muon spectrometer in order to ensure that the result of the trigger is due to a single burst of MS activity. The uncertainties shown are statistical only. The relative differences in efficiencies of the benchmark samples are a result of the different kinematics.

More…

Experimental study of the $\gamma p\rightarrow K^0\Sigma^+$, $\gamma n\rightarrow K^0\Lambda$, and $\gamma n\rightarrow K^0 \Sigma^0$ reactions at the Mainz Microtron

The A2 collaboration Akondi, C.S. ; Bantawa, K. ; Manley, D.M. ; et al.
Eur.Phys.J.A 55 (2019) 202, 2019.
Inspire Record 1703675 DOI 10.17182/hepdata.130236

This work measured $d\sigma/d\Omega$ for neutral kaon photoproduction reactions from threshold up to a c.m.\ energy of 1855MeV, focussing specifically on the $\gamma p\rightarrow K^0\Sigma^+$, $\gamma n\rightarrow K^0\Lambda$, and $\gamma n\rightarrow K^0 \Sigma^0$ reactions. Our results for $\gamma n\rightarrow K^0 \Sigma^0$ are the first-ever measurements for that reaction. These data will provide insight into the properties of $N^*$ resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $\pi N$ channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions.

28 data tables

Total cross section as a function of c.m. energy W.

Total cross section as a function of c.m. energy W.

Total cross section as a function of c.m. energy W.

More…

Measurement of the $ Z\gamma \to \nu \overline{\nu}\gamma $ production cross section in pp collisions at $ \sqrt{s}=13 $ TeV with the ATLAS detector and limits on anomalous triple gauge-boson couplings

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 12 (2018) 010, 2018.
Inspire Record 1698006 DOI 10.17182/hepdata.83965

The production of $Z$ bosons in association with a high-energy photon ($Z\gamma$ production) is studied in the neutrino decay channel of the $Z$ boson using $pp$ collisions at $\sqrt{s}$ = 13 TeV. The analysis uses a data sample with an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS detector at the LHC in 2015 and 2016. Candidate $Z\gamma$ events with invisible decays of the $Z$ boson are selected by requiring significant transverse momentum ($p_{T}$) of the dineutrino system in conjunction with a single isolated photon with large transverse energy ($E_{T}$). The rate of $Z\gamma$ production is measured as a function of photon $E_{T}$, dineutrino system $p_{T}$ and jet multiplicity. Evidence of anomalous triple gauge-boson couplings is sought in $Z\gamma$ production with photon $E_{T}$ greater than 600 GeV. No excess is observed relative to the Standard Model expectation, and upper limits are set on the strength of $ZZ\gamma$ and $Z\gamma\gamma$ couplings.

8 data tables

Measured integrated cross sections for the $Z\gamma$ process for neutrino final states at $\sqrt{s} = 13$ TeV in the extended fiducial region defined in the paper.

Measured differential cross sections for the $pp \rightarrow \nu\bar{\nu}\gamma$ process at $\sqrt{s} = 13$ TeV as a function of photon $E_{T}$ in the inclusive $N_{jets} \geq 0$ extended fiducial region defined in the paper.

Measured differential cross sections for the $pp \rightarrow \nu\bar{\nu}\gamma$ process at $\sqrt{s} = 13$ TeV as a function of photon $E_{T}$ in the exclusive $N_{jets} = 0$ extended fiducial region defined in the paper.

More…

Search for heavy Majorana or Dirac neutrinos and right-handed $W$ gauge bosons in final states with two charged leptons and two jets at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 01 (2019) 016, 2019.
Inspire Record 1696330 DOI 10.17182/hepdata.83786

A search for heavy right-handed Majorana or Dirac neutrinos $N_R$ and heavy right-handed gauge bosons $W_R$ is performed in events with a pair of energetic electrons or muons, with the same or opposite electric charge, and two energetic jets. The events are selected from $pp$ collision data with an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS detector at $\sqrt{s}$ = 13 TeV. No significant deviations from the Standard Model are observed. The results are interpreted within the theoretical framework of a left-right symmetric model and lower limits are set on masses in the heavy right-handed $W$ boson and neutrino mass plane. The excluded region extends to $m_{W_R}=4.7$ TeV for both Majorana and Dirac $N_R$ neutrinos.

20 data tables

Expected 95% CL exclusion contour in the $m_{W_R}–m_{N_R}$ plane for the Majorana $N_R$ neutrino $ee$ channel.

Observed 95% CL exclusion contour in the $m_{W_R}–m_{N_R}$ plane for the Majorana $N_R$ neutrino $ee$ channel.

Observed and expected 95% CL exclusion, for the tested signal mass hypotheses in the $m_{W_R}–m_{N_R}$ plane, for the Majorana $N_R$ neutrino $ee$ channel.

More…

Version 2
Search for squarks and gluinos in final states with hadronically decaying $\tau$-leptons, jets, and missing transverse momentum using $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 99 (2019) 012009, 2019.
Inspire Record 1688943 DOI 10.17182/hepdata.84426

A search for supersymmetry in events with large missing transverse momentum, jets, and at least one hadronically decaying $\tau$-lepton is presented. Two exclusive final states with either exactly one or at least two $\tau$-leptons are considered. The analysis is based on proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$ delivered by the Large Hadron Collider and recorded by the ATLAS detector in 2015 and 2016. No significant excess is observed over the Standard Model expectation. At 95% confidence level, model-independent upper limits on the cross section are set and exclusion limits are provided for two signal scenarios: a simplified model of gluino pair production with $\tau$-rich cascade decays, and a model with gauge-mediated supersymmetry breaking (GMSB). In the simplified model, gluino masses up to 2000 GeV are excluded for low values of the mass of the lightest supersymmetric particle (LSP), while LSP masses up to 1000 GeV are excluded for gluino masses around 1400 GeV. In the GMSB model, values of the supersymmetry-breaking scale are excluded below 110 TeV for all values of $\tan\beta$ in the range $2 \leq \tan\beta \leq 60$, and below 120 TeV for $\tan\beta>30$.

52 data tables

1$\tau$ Compressed SR eff.

1$\tau$ MediumMass SR eff.

2$\tau$ Compressed SR eff.

More…

Search for vector-boson resonances decaying to a top quark and bottom quark in the lepton plus jets final state 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 788 (2019) 347-370, 2019.
Inspire Record 1684216 DOI 10.17182/hepdata.83825

A search for new charged massive gauge bosons, $W^\prime$, is performed with the ATLAS detector at the LHC. Data were collected in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV and correspond to an integrated luminosity of 36.1 $\textrm{fb}^{-1}$. This analysis searches for $W^\prime$ bosons in the $W^\prime \rightarrow t\bar{b}$ decay channel in final states with an electron or muon plus jets. The search covers resonance masses between 0.5 and 5.0 TeV and considers right-handed $W^\prime$ bosons. No significant deviation from the Standard Model (SM) expectation is observed and upper limits are set on the $W^\prime \rightarrow t\bar{b}$ cross section times branching ratio and the $W^\prime$ boson effective couplings as a function of the $W^\prime$ boson mass. For right-handed $W^\prime$ bosons with coupling to the SM particles equal to the SM weak coupling constant, masses below 3.15 TeV are excluded at the 95% confidence level. This search is also combined with a previously published ATLAS result for $W^\prime \rightarrow t\bar{b}$ in the fully hadronic final state. Using the combined searches, right-handed $W^\prime$ bosons with masses below 3.25 TeV are excluded at the 95% confidence level.

16 data tables

Signal selection efficiency (efficiency is defined as the number of events passing all selections divided by the total number of simulated $W' \to t\bar{b} \to \ell \nu b \bar{b}$ events) in the signal region as a function of the simulated $W^\prime_{\textrm{R}}$ mass.

Distribution of the reconstructed invariant mass of the $W^\prime$ boson candidate in the 2-jet 1-tag VR$_{\textrm{HF}}$ electron validation region. Background templates are fit to data in each VR using the same statistical method as for the signal region except that the normalizations of $t\bar{t}$ and $W$+jets backgrounds are constrained to the post-fit rates obtained in the signal region. Uncertainties include all the systematic and statistical uncertainties.

Distribution of the reconstructed invariant mass of the $W^\prime$ boson candidate in the 2-jet 1-tag VR$_{\textrm{HF}}$ muon validation region. Background templates are fit to data in each VR using the same statistical method as for the signal region except that the normalizations of $t\bar{t}$ and $W$+jets backgrounds are constrained to the post-fit rates obtained in the signal region. Uncertainties include all the systematic and statistical uncertainties.

More…

Version 2
Probing the quantum interference between singly and doubly resonant top-quark production 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) 152002, 2018.
Inspire Record 1677498 DOI 10.17182/hepdata.83544

This Letter presents a normalized differential cross-section measurement in a fiducial phase-space region where interference effects between top-quark pair production and associated production of a single top quark with a $W$ boson and a $b$-quark are significant. Events with exactly two leptons ($ee$, $\mu\mu$, or $e\mu$) and two $b$-tagged jets that satisfy a multi-particle invariant mass requirement are selected from $36.1$ fb$^{-1}$ of proton-proton collision data taken at $\sqrt{s}=13$ TeV with the ATLAS detector at the LHC in 2015 and 2016. The results are compared with predictions from simulations using various strategies for the interference. The standard prescriptions for interference modeling are significantly different from each other but are within $2\sigma$ of the data. State-of-the-art predictions that naturally incorporate interference effects provide the best description of the data in the measured region of phase space most sensitive to these effects. These results provide an important constraint on interference models and will guide future model development and tuning.

15 data tables

The minimax-mbl distribution in the three-b-tag region, constructed from the two b-jets with largest transverse momentum. The predicted tt+HF contribution from simulation is scaled to match observed data in this region. The hashed band indicates the uncertainty on the total number of predicted events, where the DR scheme is used to estimate the minor contribution from the tW process. Uncertainties include all statistical and systematic sources.

The detector-level minimax-mbl distribution, with signal selection and background estimation as described in the text. The total predicted events are shown for both the DR and DS definitions of the tW process, with uncertainties on the respective estimates indicated by separate error bars. Uncertainties include all statistical and systematic sources.

The unfolded, normalized differential minimax-mbl cross-section compared with theoretical models of the tt+tWb signal with various implementations of interference effects. The uncertainty of each data point includes all statistical and systematic sources, while uncertainties for each of the MC predictions correspond to variations of the PDF set and renormalization and factorization scales.

More…

Search for resonances in the mass distribution of jet pairs with one or two jets identified as $b$-jets in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 98 (2018) 032016, 2018.
Inspire Record 1674532 DOI 10.17182/hepdata.83179

A search for new resonances decaying into jets containing b-hadrons in $pp$ collisions with the ATLAS detector at the LHC is presented in the dijet mass range from 0.57 TeV to 7 TeV. The dataset corresponds to an integrated luminosity of up to 36.1 fb$^{-1}$ collected in 2015 and 2016 at $\sqrt{s} = 13$ TeV. No evidence of a significant excess of events above the smooth background shape is found. Upper cross-section limits and lower limits on the corresponding signal mass parameters for several types of signal hypotheses are provided at 95% CL. In addition, 95% CL upper limits are set on the cross-sections for new processes that would produce Gaussian-shaped signals in the di-b-jet mass distributions.

26 data tables

The per-event b-tagging efficiencies after the event selection, as a function of the reconstructed invariant mass, for both single b-tagged and double b-tagged categories. The efficiencies are shown for simulated event samples corresponding to seven different b and Z' resonance masses in the high-mass region.

The per-event b-tagging efficiencies after the event selection, as a function of the reconstructed invariant mass, for double b-tagged category. The efficiencies are shown for simulated event samples corresponding to four different Z' resonance masses in the low-mass region. The efficiencies of identifying an event with two b-jets at trigger level only (Online) and when requiring offline confirmation (Online+offline) are shown.

Dijet mass spectra after the background only fit with the background prediction in the inclusive 1-b-tag high-mass region.

More…

Search for pair production of Higgs bosons in the $b\bar{b}b\bar{b}$ final state using proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 01 (2019) 030, 2019.
Inspire Record 1668124 DOI 10.17182/hepdata.82599

A search for Higgs boson pair production in the $b\bar{b}b\bar{b}$ final state is carried out with up to 36.1 $\mathrm{fb}^{-1}$ of LHC proton--proton collision data collected at $\sqrt{s}$ = 13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. Two analyses are carried out, each implementing a particular technique for the event reconstruction that targets Higgs bosons reconstructed as pairs of jets or single boosted jets. The resonance mass range covered is 260--3000 GeV. The analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to $b\bar{b}b\bar{b}$ are set in each model. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.

4 data tables

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the narrow-width scalar.

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the bulk Randall-Sundrum model with $\frac{k}{\overline{M}_{\mathrm{Pl}}} = 1$.

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the bulk Randall-Sundrum model with $\frac{k}{\overline{M}_{\mathrm{Pl}}} = 2$.

More…