Search for a dark photon in e(+)e(-) collisions at BABAR.

Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514  fb^{-1} of data collected with the BABAR detector.

Search for scalar diphoton resonances in the mass range 65-600 GeV with the ATLAS detector in pp collision data at √s=8 TeV.

A search for scalar particles decaying via narrow resonances into two photons in the mass range 65-600 GeV is performed using 20.3  fb(-1) of √s 8 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background.

Evidence for electroweak production of W±W±jj in pp collisions at sqrt[s] = 8 TeV with the ATLAS detector.

This Letter presents the first study of W(±)W(±)jj, same-electric-charge diboson production in association with two jets, using 20.3 fb(-1) of proton-proton collision data at sqrt[s] = 8  TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two reconstructed same-charge leptons (e(±)e(±), e(±)μ(±), and μ(±)μ(±)) and two or more jets are analyzed.

Search for CP violation in B0-B0 mixing using partial reconstruction of B0→D*- Xℓ+ νℓ and a kaon tag.

We present results of a search for CP violation in B0- B0 mixing with the BABAR detector. We select a sample of B0→D*- Xℓ+ ν decays with a partial reconstruction method and use kaon tagging to assess the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP≡[N(B0B0)-N(B0B0)]/[N(B0B0)+N(B0B0)]=(0.

Measurements of four-lepton production at the Z resonance in pp collisions at sqrt[s] = 7 and 8 TeV with ATLAS.

Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions m(ℓ+ℓ(-)) > 5 GeV and 80 View Article and Find Full Text PDF

Search for quantum black hole production in high-invariant-mass lepton+jet final states using pp collisions at √s=8 TeV and the ATLAS detector.

This Letter presents a search for quantum black-hole production using 20.3 fb-1 of data collected with the ATLAS detector in pp collisions at the LHC at √s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet.

Search for dark matter in events with a hadronically decaying W or Z boson and missing transverse momentum in pp collisions at √s=8 TeV with the ATLAS detector.

A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3  fb(-1) of integrated luminosity at √s=8  TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed.

Measurement of top quark polarization in top-antitop events from proton-proton collisions at √s=7 TeV using the ATLAS detector.

This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7  fb(-1) of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at √s=7  TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered.

Measurement of distributions sensitive to the underlying event in inclusive Z-boson production in [Formula: see text] collisions at [Formula: see text] TeV with the ATLAS detector.

A measurement of charged-particle distributions sensitive to the properties of the underlying event is presented for an inclusive sample of events containing a [Formula: see text]-boson, decaying to an electron or muon pair. The measurement is based on data collected using the ATLAS detector at the LHC in proton-proton collisions at a centre-of-mass energy of [Formula: see text] TeV with an integrated luminosity of [Formula: see text] fb[Formula: see text]. Distributions of the charged particle multiplicity and of the charged particle transverse momentum are measured in regions of azimuthal angle defined with respect to the [Formula: see text]-boson direction.

A measurement of the ratio of the production cross sections for [Formula: see text] and [Formula: see text] bosons in association with jets with the ATLAS detector.

The ratio of the production cross sections for [Formula: see text] and [Formula: see text] bosons in association with jets has been measured in proton-proton collisions at [Formula: see text] with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of [Formula: see text]. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum [Formula: see text] and jet rapidity [Formula: see text].

Search for contact interactions and large extra dimensions in the dilepton channel using proton-proton collisions at [Formula: see text] 8 TeV with the ATLAS detector.

A search is conducted for non-resonant new phenomena in dielectron and dimuon final states, originating from either contact interactions or large extra spatial dimensions. The LHC 2012 proton-proton collision dataset recorded by the ATLAS detector is used, corresponding to 20 fb[Formula: see text] at [Formula: see text] = 8 TeV. The dilepton invariant mass spectrum is a discriminating variable in both searches, with the contact interaction search additionally utilizing the dilepton forward-backward asymmetry.

Muon reconstruction efficiency and momentum resolution of the ATLAS experiment in proton-proton collisions at [Formula: see text] TeV in 2010.

This paper presents a study of the performance of the muon reconstruction in the analysis of proton-proton collisions at [Formula: see text] TeV at the LHC, recorded by the ATLAS detector in 2010. This performance is described in terms of reconstruction and isolation efficiencies and momentum resolutions for different classes of reconstructed muons. The results are obtained from an analysis of [Formula: see text] meson and [Formula: see text] boson decays to dimuons, reconstructed from a data sample corresponding to an integrated luminosity of 40 pb[Formula: see text].

Light-quark and gluon jet discrimination in [Formula: see text] collisions at [Formula: see text] with the ATLAS detector.

A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb[Formula: see text] of proton-proton collision data at [Formula: see text] [Formula: see text] collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant.

Measurement of the centrality and pseudorapidity dependence of the integrated elliptic flow in lead-lead collisions at [Formula: see text] TeV with the ATLAS detector.

The integrated elliptic flow of charged particles produced in Pb+Pb collisions at [Formula: see text] TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, [Formula: see text], was measured in the pseudorapidity range [Formula: see text] with the event-plane method. In order to include tracks with very low transverse momentum [Formula: see text], thus reducing the uncertainty in [Formula: see text] integrated over [Formula: see text], a [Formula: see text] data sample recorded without a magnetic field in the tracking detectors is used.

Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data.

Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at [Formula: see text] TeV and corresponding to an integrated luminosity of 4.7 fb[Formula: see text].

Search for direct top squark pair production in events with a [Formula: see text] boson, [Formula: see text]-jets and missing transverse momentum in [Formula: see text] TeV [Formula: see text] collisions with the ATLAS detector.

A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the [Formula: see text] boson mass, jets tagged as originating from [Formula: see text]-quarks and missing transverse momentum. The analysis is performed with proton-proton collision data at [Formula: see text] collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb[Formula: see text].

Measurement of flow harmonics with multi-particle cumulants in Pb+Pb collisions at [Formula: see text] TeV with the ATLAS detector.

ATLAS measurements of the azimuthal anisotropy in lead-lead collisions at [Formula: see text] TeV are shown using a dataset of approximately 7 [Formula: see text]b[Formula: see text] collected at the LHC in 2010. The measurements are performed for charged particles with transverse momenta [Formula: see text] GeV and in the pseudorapidity range [Formula: see text]. The anisotropy is characterized by the Fourier coefficients, [Formula: see text], of the charged-particle azimuthal angle distribution for [Formula: see text]-4.

Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton-proton collision data.

This paper presents the performance of the ATLAS muon reconstruction during the LHC run with [Formula: see text] collisions at [Formula: see text]-8 TeV in 2011-2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of [Formula: see text], [Formula: see text] and [Formula: see text] decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided.

Measurements of jet vetoes and azimuthal decorrelations in dijet events produced in [Formula: see text] collisions at [Formula: see text] using the ATLAS detector.

Additional jet activity in dijet events is measured using [Formula: see text] collisions at ATLAS at a centre-of-mass energy of [Formula: see text], for jets reconstructed using the [Formula: see text] algorithm with radius parameter [Formula: see text]. This is done using variables such as the fraction of dijet events without an additional jet in the rapidity interval bounded by the dijet subsystem and correlations between the azimuthal angles of the dijet s. They are presented, both with and without a veto on additional jet activity in the rapidity interval, as a function of the scalar average of the transverse momenta of the dijet s and of the rapidity interval size.

Measurement of the [Formula: see text] production cross-section using [Formula: see text] events with [Formula: see text]-tagged jets in [Formula: see text] collisions at [Formula: see text] and 8 TeV with the ATLAS detector.

The inclusive top quark pair ([Formula: see text]) production cross-section [Formula: see text] has been measured in proton-proton collisions at [Formula: see text] and [Formula: see text] with the ATLAS experiment at the LHC, using [Formula: see text] events with an opposite-charge [Formula: see text] pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 [Formula: see text] and the 2012 8 TeV dataset of 20.

Measurement of the azimuthal angle dependence of inclusive jet yields in Pb+Pb collisions at √(sNN)=2.76 TeV with the ATLAS detector.

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δφ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δφ dependence of jet yields in 0.14 nb(-1) of √(s(NN))=2.

Measurement of the D*(2010)+ meson width and the D*(2010)+ - D0 mass difference.

We measure the mass difference Δm0 between the D*(2010)+ and the D0 and the natural linewidth Γ of the transition D*(2010)+ → D0π+. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477  fb(-1). The D0 is reconstructed in the decay modes D0 → K- π+ and D0 → K- π+ π- π+.

Observation of associated near-side and away-side long-range correlations in sqrt[s(NN)]=5.02 TeV proton-lead collisions with the ATLAS detector.

Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.

Measurement of splitting scales in → events at [Formula: see text] with the ATLAS detector.

A measurement of splitting scales, as defined by the clustering algorithm, is presented for final states containing a boson produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing bosons decaying to electrons or muons.

Measurement of jet shapes in top-quark pair events at [Formula: see text] using the ATLAS detector.

A measurement of jet shapes in top-quark pair events using 1.8 fb of [Formula: see text] collision data recorded by the ATLAS detector at the LHC is presented. Samples of top-quark pair events are selected in both the single-lepton and dilepton final states.