Electron reconstruction and identification in the ATLAS experiment using the 2015 and 2016 LHC proton-proton collision data at √ s = 13 TeVThe ATLAS Collaboration Algorithms used for the reconstruction and identification of electrons in the central region of the ATLAS detector at the Large Hadron Collider (LHC) are presented in this paper; these algorithms are used in ATLAS physics analyses that involve electrons in the final state and which are based on the 2015 and 2016 proton-proton collision data produced by the LHC at √ s = 13 TeV. The performance of the electron reconstruction, identification, isolation, and charge identification algorithms is evaluated in data and in simulated samples using electrons from Z → ee and J/ψ → ee decays. Typical examples of combinations of electron reconstruction, identification, and isolation operating points used in ATLAS physics analyses are shown.

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This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 µm, which corresponds to a momentum accuracy of about 10% at p T = 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data with an integrated luminosity of 36.1 fb −1 collected in 2015 and 2016 from proton-proton collisions at √ s = 13 TeV are examined. Particles producing anomalously high ionization, consistent with long-lived massive particles with electric charges from |q| = 2e to |q| = 7e, are searched for. No events are observed, and 95% confidence level cross-section upper limits are interpreted as lower mass limits for a Drell-Yan production model. Multicharged particles with masses between 50 GeV and 980-1220 GeV (depending on their electric charge) are excluded. 100 kHz. This is followed by the software-based high-level trigger, which reduces the event rate to about 1 kHz.The amount of material in the ID varies from one-half to two radiation lengths. The overall amount of material traversed by an MCP up to the last measurement surface, which includes the calorimeters and the MS, may be as high as 75 radiation lengths. Muons typically lose 3 GeV penetrating the calorimeter system. The energy loss for MCPs with charge z would be z 2 times this value, i.e. up to 150 GeV for z = 7.The muon transverse momentum measured by the MS after the energy loss in the calorimeters is denoted by p µ T , while transverse momentum of charged particles measured by the ID or the combination of the ID and MS is denoted by p T . Charged-particle trajectories are reconstructed using standard algorithms. Since these algorithms assume particles with unit electric charge, the momenta of MCPs are underestimated by a factor z, as the track curvature is proportional to p T /z. Samples of simulated eventsBenchmark samples of simulated events with MCPs were generated for a mass of 50 GeV and for a range of masses between 200 and 1400 GeV in steps of 200 GeV, for charges ze with z = 2, 2.5, . . . , 7. Lepton-like pairs of MCPs were generated via the lowest-order Drell-Yan (DY) process implemented in M G 5_aMC@NLO 2.3.3 [19] with only photon exchange included. This implementation of the DY production process models the kinematic distributions and determines the cross-sections. Cross-section values for MCP pair production range from hundreds of picobarns (mass of 50 GeV, z = 7) down to a hundredth of a femtobarn (mass of 1400 GeV, z = 2). Events were generated using the NNPDF23LO [20] parton distribution functions with the A14 set of tuned parameters [21], and P 8.205 [22, 23] was used for hadronization and underlying-event generation.Simulated samples with muons from Z → µµ decays were generated using P -B v2 [24,25] interfaced to the P 8.186 parton shower model. The AZNLO tuned parameters [26] were employed, with the CTEQ6L1 PDF set [27] for the modeling of non-perturbative effects. The E G 1.2.0 program [28] was utilized for the properties of band c-hadron decays.A full G 4 simulation [29, 30] was used to model the response of the ATLAS detector. Each simulated hard-scattering event was overlaid with simulated minimum-bias events ("pileup") gen...

The results of a search for squarks and gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton-proton collision data at a center-of-mass energy of ffiffi ffi s p ¼ 13 TeV are presented. The data set used was recorded during 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb −1 . No significant excess beyond the expected background is found. Exclusion limits at 95% confidence level are set in a number of supersymmetric scenarios, reaching masses up to 2.1 TeV for gluino pair production and up to 1.25 TeV for squark pair production.