A measurement is presented of the phi to K+K- production cross section at sqrt(s) = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mub-1, collected with the ATLAS experiment at the LHC. Selection of phi(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, pTphi, and rapidity, |yphi|, of the phi(1020) meson in the fiducial region 500 < pTphi< 1200 MeV, |yphi| < 0.8, kaon pTK> 230 MeV and kaon momentum pK< 800 MeV.The integrated phi(1020)-meson production cross section in this fiducial range is measured to be s(phi K+K-) = 570 pm 8 (stat) pm 66 (syst) pm 20 (lumi) mub.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) transverse momentum.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) rapidity.
The integrated PHI(1020) meson production cross section in the fiducial region.
Measurements are presented of differential cross-sections for top quark pair production in pp collisions at sqrt(s) = 7 TeV relative to the total inclusive top quark pair production cross-section. A data sample of 2.05/fb recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector effects, normalized to the total inclusive top quark pair production cross-section and compared to theoretical predictions. The measurement uncertainties range typically between 10% and 20% and are generally dominated by systematic effects. No significant deviations from the Standard Model expectations are observed.
Relative differential cross-section (1/SIG)*D(SIG)/DM(ttbar) measured in the e+jets, mu+jets and the combined lepton+jets channel.
Relative differential cross-section (1/SIG)*D(SIG)/DPT(ttbar) measured in the e+jets, mu+jets and the combined lepton+jets channel.
Relative differential cross-section (1/SIG)*D(SIG)/DYRAP(ttbar) measured in the e+jets, mu+jets and the combined lepton+jets channel.
This paper presents a measurement of the W^+W^- production cross section in pp collisions at sqrt{s}=7 TeV. The leptonic decay channels are analyzed using data corresponding to an integrated 4.6 fb-1 collected with the ATLAS detector at the Large Hadron Collider. The W^+W^- production cross section sigma(pp -> W^+W^-+X) is measured to be 51.9 +- 2.0 (stat) +- 3.9 (syst) +- 2.0 (lumi) pb, compatible with the Standard Model prediction of 44.7 +2.1 -1.9 pb. A measurement of the normalized fiducial cross section as a function of the leading lepton transverse momentum is also presented. The reconstructed transverse momentum distribution of the leading lepton is used to extract limits on anomalous WWZ and WWgamma couplings.
The measured fiducial cross section in the three channels . The first systematic (sys) error is the combined systematic uncertainty excluding that of the luminosity. The second (sys) error is the uncertainty on the luminosity.
The measured total cross section in the three channels. The first systematic (sys) error is the combined systematic uncertainty excluding that of the luminosity. The second (sys) error is the uncertainty on the luminosity.
The measured total cross section (combined). The first systematic (sys) error is the combined systematic uncertainty excluding that of the luminosity. The second (sys) error is the uncertainty on the luminosity.
A measurement of the $ZZ$ production in the $\ell^{-}\ell^{+}\ell^{\prime -}\ell^{\prime +}$ and $\ell^{-}\ell^{+}\nu\bar{\nu}$ channels $(\ell = e, \mu)$ in proton--proton collisions at $\sqrt{s} = 8$ TeV at the Large Hadron Collider at CERN, using data corresponding to an integrated luminosity of 20.3 fb$^{-1}$ collected by the ATLAS experiment in 2012 is presented. The fiducial cross sections for $ZZ\to\ell^{-}\ell^{+}\ell^{\prime -}\ell^{\prime +}$ and $ZZ\to \ell^{-}\ell^{+}\nu\bar{\nu}$ are measured in selected phase-space regions. The total cross section for $ZZ$ events produced with both $Z$ bosons in the mass range 66 to 116 GeV is measured from the combination of the two channels to be $7.3\pm0.4\textrm{(stat)}\pm0.3\textrm{(syst)}\pm0.2\textrm{(lumi)}$ pb, which is consistent with the Standard Model prediction of $6.6^{+0.7}_{-0.6}$ pb. The differential cross sections in bins of various kinematic variables are presented. The differential event yield as a function of the transverse momentum of the leading $Z$ boson is used to set limits on anomalous neutral triple gauge boson couplings in $ZZ$ production.
The measured fiducial cross sections and the combined total cross section compared to the SM predictions. For experimental results, the statistical, systematic, and luminosity uncertainties are shown. For the theoretical predictions, the combined statistical and systematic uncertainty is shown.
The measured differential cross-section normalized to the bin width in values of the leading reconstructed dilepton pT for the 4 lepton channel. The first systematic uncertainty is detector systematics, the second is background systematic uncertainties.
The measured differential cross-section normalized to the bin width in values of the number of reconstructed jets for the 4 lepton channel. The first systematic uncertainty is detector systematics, the second is background systematic uncertainties.
Measurements of the production cross section of a $Z$ boson in association with jets in proton-proton collisions at $\sqrt{s} = 13$ TeV are presented, using data corresponding to an integrated luminosity of 3.16 fb$^{-1}$ collected by the ATLAS experiment at the CERN Large Hadron Collider in 2015. Inclusive and differential cross sections are measured for events containing a $Z$ boson decaying to electrons or muons and produced in association with up to seven jets with $p_T > 30$ GeV and $|y| <2.5$. Predictions from different Monte Carlo generators based on leading-order and next-to-leading-order matrix elements for up to two additional partons interfaced with parton shower and fixed-order predictions at next-to-leading order and next-to-next-to-leading order are compared with the measured cross sections. Good agreement within the uncertainties is observed for most of the modelled quantities, in particular with the generators which use next-to-leading-order matrix elements and the more recent next-to-next-to-leading-order fixed-order predictions.
Measured fiducial cross sections for successive exclusive jet multiplicities in the electron channel. The statistical, systematic, and luminosity uncertainties are given.
Measured fiducial cross sections for successive exclusive jet multiplicities in the electron channel. The statistical, systematic, and luminosity uncertainties are given.
Measured fiducial cross sections for successive exclusive jet multiplicities in the muon channel. The statistical, systematic, and luminosity uncertainties are given.
A measurement of the cross section for the production of an isolated photon in association with jets in proton-proton collisions at a center-of-mass energy $\sqrt{s}$ = 7 TeV is presented. Photons are reconstructed in the pseudorapidity range $|\eta^{\gamma}| \lt 1.37$ and with a transverse energy $E_T^\gamma$ > 25 GeV. Jets are reconstructed in the rapidity range $|y^{jet}|$ < 4.4 and with a transverse momentum $p_T^{jet}$ > 20 GeV. The differential cross section $d\sigma/dE_T^\gamma$ is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-$p_T$ jet: $|y^{jet}| < 1.2, 1.2 \le |y^{jet}|$ < 2.8 and 2.8 $\le |y^{jet}|$ < 4.4. For each rapidity configuration the same-sign $(\eta^{\gamma}y^{jet}\ge 0)$ and opposite-sign $(\eta^{\gamma}y^{jet}<0)$ cases are studied separately. The results are based on an integrated luminosity of 37 pb$^{-1}$, collected with the ATLAS detector at the LHC. Next-to-leading order perturbative QCD calculations are found to be in fair agreement with the data, except for $E_T^{\gamma} \lt 45$ GeV, where the theoretical predictions overestimate the measured cross sections.
The measured cross section as a function of the photon transverse energy, ET, for pT(jet)>20 GeV, |eta(gamma)|<1.37, |y(jet)|<1.2, eta(gamma)*y(jet)>=0.
The measured cross section as a function of the photon transverse energy, ET, for pT(jet)>20 GeV, |eta(gamma)|<1.37, 1.2<=|y(jet)|<2.8, eta(gamma)*y(jet)>=0.
The measured cross section as a function of the photon transverse energy, ET, for pT(jet)>20 GeV, |eta(gamma)|<1.37, 2.8<=|y(jet)|<4.4, eta(gamma)*y(jet)>=0.
Measurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from $pp$ collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb$^{-1}$. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measured cross sections, which are compared to several predictions, allow a detailed study of top quark production.
Statistical correlation matrix between |$p_{out}^{t\bar{t}}$| in the 4-jet exclusive configuration and |$p_{out}^{t\bar{t}}$| in the 4-jet exclusive configuration, obtained through the Bootstrap Method.
Statistical correlation matrix between |$p_{out}^{t\bar{t}}$| in the 4-jet exclusive configuration and $p_{T}^{t,had}$ in the 4-jet exclusive configuration, obtained through the Bootstrap Method.
Statistical correlation matrix between |$p_{out}^{t\bar{t}}$| in the 4-jet exclusive configuration and $p_{T}^{t\bar{t}}$ in the 4-jet exclusive configuration, obtained through the Bootstrap Method.
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.
Covariance matrix of the absolute cross-section as function of the top quark pT, accounting for the statistical and systematic uncertainties in the resolved topology.
Covariance matrix of the absolute cross-section as function of the top quark pT, accounting for the statistical and systematic uncertainties in the resolved topology.
Covariance matrix of the relative cross-section as function of the top quark pT, accounting for the statistical and systematic uncertainties in the resolved topology.
The cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV with $20.2$ fb$^{-1}$ of data collected by the ATLAS detector at the Large Hadron Collider in 2012. The measurement is performed by selecting events that contain a photon with transverse momentum $p_\mathrm{T} > 15$ GeV, an isolated lepton with large transverse momentum, large missing transverse momentum, and at least four jets, where at least one is identified as originating from a $b$-quark. The production cross section is measured in a fiducial region close to the selection requirements. It is found to be $139 \pm 7 (\mathrm{stat.}) \pm 17 (\mathrm{syst.})$ fb, in good agreement with the theoretical prediction at next-to-leading order of $151 \pm 24$ fb. In addition, differential cross sections in the fiducial region are measured as a function of the transverse momentum and pseudorapidity of the photon.
The measured fiducial cross sections. The first uncertainty is the statistical uncertainty and the second is the systematic uncertainty
differential cross section as function of the photon pT. The first uncertainty is the statistical uncertainty and the second is the systematic uncertainty
differential cross section as function of the photon pseudorapidity. The first uncertainty is the statistical uncertainty and the second is the systematic uncertainty
This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton-proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb$^{-1}$. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: $|\eta^\gamma|<1.37$ and $1.56<|\eta^\gamma|<2.37$. The measurement covers photon transverse energies $25 < E_\textrm{T}^\gamma<400$ GeV and $25 < E_\textrm{T}^\gamma<350$ GeV respectively for the two $|\eta^\gamma|$ regions. For each jet flavour, the ratio of the cross sections in the two $|\eta^\gamma|$ regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central $\gamma+b$ measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.
Measured fiducial integrated $\gamma+b$ and $\gamma+c$ cross sections for $|\eta^\gamma|<1.37$ and $1.56<|\eta^\gamma|<2.37$.
Measured $\gamma+b$ fiducial differential cross section as a function of $E_\text{T}^\gamma$ for $|\eta^\gamma|<1.37$.
Measured $\gamma+b$ fiducial differential cross section as a function of $E_\text{T}^\gamma$ for $1.56<|\eta^\gamma|<2.37$.