Inspire | HepData | arXiv:1704.03839 [hep-ex] | submitted to PRD
A measurement of the production cross section for two isolated photons in proton--proton collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV is presented. The results are based on an integrated luminosity of 20.2 fb$^{-1}$ recorded by the ATLAS detector at the Large Hadron Collider. The measurement considers photons with pseudorapidities satisfying $|\eta^\gamma| < 1.37$ or $1.56 < |\eta^\gamma| < 2.37$ and transverse energies of respectively $E^\gamma_\text{T,1}>40$ GeV and $E^\gamma_\text{T,2}> 30$ GeV for the two leading photons ordered in transverse energy produced in the interaction. The background due to hadronic jets and electrons is subtracted using data-driven techniques. The fiducial cross sections are corrected for detector effects and measured differentially as a function of six kinematic observables. The measured cross section integrated within the fiducial volume is $16.8\pm0.8$ pb. The data are compared to fixed-order QCD calculations at next-to-leading-order and next-to-next-to-leading-order accuracy as well as next-to-leading-order computations including resummation of initial-state gluon radiation at next-to-next-to-leading logarithm or matched to a parton shower, with relative uncertainties varying from 5% to 20%.
Inspire | HepData | arXiv:1605.03495 [hep-ex]
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV is presented. The measurement covers the pseudorapidity ranges $|\eta^\gamma| < 1.37$ $1.56 < |\eta^\gamma| < 2.37$ in the transverse energy range $25 < E^\gamma_\text{T} < 1500$ GeV. The results are based on an integrated luminosity of 20.2 fb${}^{-1}$, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on the observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate.
Inspire | HepData | JHEP 1609 (2016) 029 | doi:10.1007/JHEP09(2016)029 | arXiv:1603.01702 [hep-ex]
The production of $W$ boson pairs in proton-proton collisions at $\sqrt{s} = 8$ TeV is studied using data corresponding to 20.3 fb${}^{-1}$ of integrated luminosity collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The $W$ bosons are reconstructed using their leptonic decays into electrons or muons and neutrinos. Events with reconstructed jets are not included in the candidate event sample. A total of 6636 $WW$ candidate events are observed. Measurements are performed in fiducial regions closely approximating the detector acceptance. The integrated measurement is corrected for all acceptance effects and for the $W$ branching fractions to leptons in order to obtain the total $WW$ production cross section, which is found to be $71.1 \pm 1.1$ (stat) ${}^{+5.7}_{-5.0}$ (syst) $\pm 1.4$ (lumi) pb. This agrees with the next-to-next-to-leading-order Standard Model prediction of $63.2 {}^{+1.6}_{-1.4}$ (scale) $\pm 1.2$ (PDF) pb. Fiducial differential cross sections are measured as a function of each of six kinematic variables. The distribution of the transverse momentum of the leading lepton is used to set limits on anomalous triple-gauge-boson couplings.
Inspire | HepData | arXiv:1512.02192 [hep-ex] | submitted to EPJC
Distributions of transverse momentum $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=8$\,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proto--proton collisions at i$\sqrt{s}=7$\,TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the $Z$-boson mass peak. Specify the lepton channel (default is Z->ee) by using the dedicated plugins ATLAS_2015_I1408516_EL and ATLAS_2015_I1408516_MU.
Inspire | HepData | arXiv:1512.02192 [hep-ex] | submitted to EPJC
Distributions of transverse momentum $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=8$\,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proto--proton collisions at i$\sqrt{s}=7$\,TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the $Z$-boson mass peak. Specify the lepton channel (default is Z->ee) by using the dedicated plugins ATLAS_2015_I1408516_EL and ATLAS_2015_I1408516_MU.
Inspire | HepData | arXiv:1512.02192 [hep-ex] | submitted to EPJC
Distributions of transverse momentum $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=8$\,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proto--proton collisions at i$\sqrt{s}=7$\,TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the $Z$-boson mass peak. Specify the lepton channel (default is Z->ee) by using the dedicated plugins ATLAS_2015_I1408516_EL and ATLAS_2015_I1408516_MU.
Inspire | HepData | Phys.Rev. D93 (2016) no.3, 032009 | doi:10.1103/PhysRevD.93.032009 | arXiv:1510.03818 [hep-ex]
The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3fb${}^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for $t\bar{t}$ events in the lepton+jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti-$k_\text{t}$ jet with radius parameter $R=1.0$ and identified with jet substructure techniques. The observed yield is corrected for detector effects to obtain a cross-section at particle level in a fiducial region close to the event selection.
Inspire | HepData | Phys.Lett. B753 (2016) 552-572 | doi:10.1016/j.physletb.2015.12.048 | arXiv:1509.07844 [hep-ex]
The four-lepton (4$\ell$, $\ell = e,\mu$) production cross section is measured in the mass range from 80 to 1000 GeV using 20.3 fb$^{-1}$ of data in $pp$ collisions at $\sqrt{s}=8$ TeV collected with the ATLAS detector at the LHC. The $4\ell$ events are produced in the decays of resonant $Z$ and Higgs bosons and the non-resonant $ZZ$ continuum originating from $q\bar{q}$, $gg$, $qg$ initial states. A total of 476 signal candidate events are observed with a background expectation of 26.2$\pm$3.6 events, enabling the measurement of the integrated cross section and the differential cross section as a function of the invariant mass and transverse momentum of the four-lepton system.
Inspire | HepData | JHEP 1404 (2014) 031 | arXiv:1401.7610 [hep-ex]
Measurements differential distributions for inclusive $Z$-boson-plus-dijet production are performed in five fiducial regions, each with different sensitivity to the electroweak contribution. Measured distributions include the differential cross section as a function of the dijet invariant mass, the differential cross section and a function of the dijet rapidity separation, the differential cross section as a function of the number of jets in the rapidity interval bounded by the two leading jets. Other measurements include the jet veto effiency as a function of the dijet invariant mass and rapdity separation, the normalized transverse momentum balance cut efficiency, and the average number of jets falling into the rapidity interval boundd by the two leading jets, as a function of dijet invariant mass and dijet rapidity separation.
Inspire | HepData | CMS-PAS-TOP-14-012 (PAS) | CERN-EP-2016-078 (paper)
The cross section for pair production of top quarks with high transverse momenta ($p_{\rm T} > 400$ GeV) is measured in 19.7 fb$^{-1}$ of $\mathrm{pp}$ collisions, collected with the CMS detector at $\sqrt{s} = 8$ TeV. The measurement is performed for lepton+jets events, where one top quark decays according to $t \rightarrow Wb \rightarrow \ell \nu b$, with $\ell$ denoting an electron or muon, and the second top quark decays to an hadronic final state and is reconstructed as a single, large-radius jet and identified as a top quark candidate using jet substructure techniques. Integrated cross sections, as well as differential cross sections as a function of the top quark $p_{\rm T}$ and rapidity, are measured both at particle level within a fiducial region resembling the detector-level selections and at parton level. RIVET: This analysis is to be run on ${\rm t\bar{t}}$ Monte Carlo. It utilizes the PartonicTops projection, which assumes top quarks in the event record. The analysis has been validated with Powheg+Pythia6. The parton-level phase space is defined by requiring two PartonicTops. Exactly one PartonicTop must decay directly to a muon or electron (no intermediate tau), and exactly one PartonicTop decays hadronically. For for $t\bar{t}$ Monte Carlo, this is equivalent to requiring the event to be semileptonic at parton level. The parton-level top quark is defined as the hadronically decaying top. The parton-level top quark is required to have $p_{T} > 400$ GeV. The particle-level phase space is defined using the following object definitions: - Lepton: A dressed electron or muon, meaning the lepton has been clustered with all photons within a cone of $R=0.1$. The DressedLepton projection is used to construct the dressed lepton. The lepton is required to have $p_{T} > 45$ GeV and $|\eta| < 2.1$. - B Jet Candidate: Gen AK5 jets are formed by clustering the final state particles in the event using the anti-$k_{T}$ algorithm with distance parameter $R=0.5$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen AK5 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen AK5 jets in the same hemisphere as the lepton ($\Delta {\rm R(e/\mu, jet)} < \pi/2$) are defined as b-jet candidates. - Top Jet Candidate: Gen CA8 jets are formed by clustering the final state particles in the event using the Cambridge-Aachen algorithm with distance parameter $R=0.8$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen CA8 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen CA8 jets which have $p_{T} > 400$ GeV, 140 GeV $<$ mass $<$ 250 GeV, and are in the opposite hemisphere from the lepton ($\Delta{\rm R(e/\mu, jet)} > \pi/2$) are defined as top jet candidates. The particle-level phase space is defined by requiring $\geq 1$ b jet candidate, $\geq 1$ top jet candidate, and exactly one lepton. This is in addition to the parton-level semileptonic requirement. The highest-$p_{T}$ top jet candidate is defined as the particle-level t jet.
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