Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton-proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton-proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of [Formula: see text] TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about [Formula: see text] is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than [Formula: see text] and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Search for new resonances decaying to a WW or ZZ boson and a Higgs boson in the ℓ+ℓ−bbˉ\ell^+ \ell^- b\bar b, ℓνbbˉ\ell \nu b\bar b, and ννˉbbˉ\nu\bar{\nu} b\bar b channels with pppp collisions at s=13\sqrt s = 13 TeV with the ATLAS detector

See paper for full list of authors, 18 pages (plus author list + cover pages: 36 pages total), 13 figures, 1 table. Submitted to PLB. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2015-18/International audienceA search is presented for new resonances decaying to a $W$ or $Z$ boson and a Higgs boson in the $\ell^+ \ell^- b\bar b$, $\ell\nu b\bar b$, and $\nu\bar{\nu} b\bar b$ channels in $pp$ collisions at $\sqrt s = 13$ TeV with the ATLAS detector at the Large Hadron Collider using a total integrated luminosity of 3.2 fb$^{-1}$. The search is conducted by looking for a localized excess in the $WH$/$ZH$ invariant or transverse mass distribution. No significant excess is observed, and the results are interpreted in terms of constraints on a simplified model based on a phenomenological Lagrangian of heavy vector triplets