A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb −1 of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at √ s = 13 TeV. Three R-parity-conserving scenarios where the lightest neutralino is the lightest supersymmetric particle are considered: the production of chargino pairs with decays via either W bosons or sleptons, and the direct production of slepton pairs. The analysis is optimised for the first of these scenarios, but the results are also interpreted in the others. No significant deviations from the Standard Model expectations are observed and limits at 95% confidence level are set on the masses of relevant supersymmetric particles in each of the scenarios. For a massless lightest neutralino, masses up to 420 GeV are excluded for the production of the lightest-chargino pairs assuming W-boson-mediated decays and up to 1 TeV for slepton-mediated decays, whereas for slepton-pair production masses up to 700 GeV are excluded assuming three generations of mass-degenerate sleptons. Contents

Search for additional heavy neutral Higgs and gauge bosons in the ditau final state produced in 36 fb −1 of pp collisions at √ s = 13 TeV with the ATLAS detectorThe ATLAS collaboration E-mail: atlas.publications@cern.ch Abstract: A search for heavy neutral Higgs bosons and Z bosons is performed using a data sample corresponding to an integrated luminosity of 36.1 fb −1 from proton-proton collisions at √ s = 13 TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to τ + τ − with at least one tau lepton decaying to final states with hadrons and a neutrino. The search is performed in the mass range of 0.2-2.25 TeV for Higgs bosons and 0.2-4.0 TeV for Z bosons. The data are in good agreement with the background predicted by the Standard Model. The results are interpreted in benchmark scenarios. In the context of the hMSSM scenario, the data exclude tan β > 1.0 for m A = 0.25 TeV and tan β > 42 for m A = 1.5 TeV at the 95% confidence level. For the Sequential Standard Model, Z SSM with m Z < 2.42 TeV is excluded at 95% confidence level, while Z NU with m Z < 2.25 TeV is excluded for the non-universal G(221) model that exhibits enhanced couplings to third-generation fermions. 6 Background estimation 10 6.1 Jet background estimate in the τ had τ had channel 10 6.1. The ATLAS collaboration 37-1 - JHEP01(2018)0551 IntroductionThe discovery of a scalar particle [1, 2] at the Large Hadron Collider (LHC) [3] has provided important insight into the mechanism of electroweak symmetry breaking. Experimental studies of the new particle [4][5][6][7][8] demonstrate consistency with the Standard Model (SM) Higgs boson [9][10][11][12][13][14]. However, it remains possible that the discovered particle is part of an extended scalar sector, a scenario that is predicted by a number of theoretical arguments [15,16]. The Minimal Supersymmetric Standard Model (MSSM) [15,17,18] is the simplest extension of the SM that includes supersymmetry. The MSSM requires two Higgs doublets of opposite hypercharge. Assuming that CP symmetry is conserved, this results in one CPodd (A) and two CP-even (h, H) neutral Higgs bosons and two charged Higgs bosons (H ± ). At tree level, the properties of the Higgs sector in the MSSM depend on only two non-SM parameters, which can be chosen to be the mass of the CP-odd Higgs boson, m A , and the ratio of the vacuum expectation values of the two Higgs doublets, tan β. Beyond tree level, a number of additional parameters affect the Higgs sector, the choice of which defines various MSSM benchmark scenarios. In the m mod+ h scenario [19], the top-squark mixing parameter is chosen such that the mass of the lightest CP-even Higgs boson, m h , is close to the measured mass of the Higgs boson that was discovered at the LHC. A different approach is employed in the hMSSM scenario [20,21] in which the measured value of m h can be used, with certain assumptions, to predict the remaining masses and couplings of the MSSM Higgs bosons without explicit reference to the sof...

A measurement of the production processes of the recently discovered Higgs boson is performed in the two-photon final state using 4.5 fb −1 of proton-proton collisions data at ffiffi ffi s p ¼ 7 TeV and 20.3 fb −1 at ffiffi ffi s p ¼ 8 TeV collected by the ATLAS detector at the Large Hadron Collider. The number of observed Higgs boson decays to diphotons divided by the corresponding Standard Model prediction, called the signal strength, is found to be μ ¼ 1.17 AE 0.27 at the value of the Higgs boson mass measured by ATLAS, m H ¼ 125.4 GeV. The analysis is optimized to measure the signal strengths for individual Higgs boson production processes at this value of m H . They are found to be μ ggF ¼ 1.32 AE 0.38, μ VBF ¼ 0.8 AE 0.7, μ WH ¼ 1.0 AE 1.6, μ ZH ¼ 0.1 þ3.7 −0.1 , and μ ttH ¼ 1.6 þ2.7 −1.8 , for Higgs boson production through gluon fusion, vector-boson fusion, and in association with a W or Z boson or a top-quark pair, respectively. Compared with the previously published ATLAS analysis, the results reported here also benefit from a new energy calibration procedure for photons and the subsequent reduction of the systematic uncertainty on the diphoton mass resolution. No significant deviations from the predictions of the Standard Model are found.

This paper presents the performance of the ATLAS muon reconstruction during the LHC run with collisions at –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 , and decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided. Over most of the covered phase space (muon and  GeV) the efficiency is above and is measured with per-mille precision. The momentum resolution ranges from at central rapidity and for transverse momentum  GeV, to at large rapidity and  GeV. The momentum scale is known with an uncertainty of to depending on rapidity. A method for the recovery of final state radiation from the muons is also presented.

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