The analysis of the data collected by the NA50 experiment in 1998, reported in this paper, extends and clarifies the pattern of the previously observed J/ψ anomalous suppression. This new measurement, besides providing a deeper understanding of the previous observations, reveals a steady significative decrease in the J/ψ production rate up to the most central Pb-Pb collisions. It clearly rules out the presently available conventional (hadronic) models of J/ψ suppression, which unanimously predict a saturation of the J/ψ rate for central Pb-Pb collisions. On the contrary and together with the sharp onset of the anomalous suppression previously reported, the new observation leads to a global production rate pattern which finds its natural explanation in the framework of the formation of a deconfined state of quarks and gluons. Accepted by Phys. Lett. B 1) Università del Piemonte Orientale, Alessandria and INFN-Torino, Italy 2) Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, Annecy-le-Vieux, France 3) Laboratoire de Physique Corpusculaire (LPC), Université Blaise Pascal, IN2P3-CNRS, Aubière, France 4) Institute of Atomic Physics (IFA), Bucharest, Romania 5) Università di Cagliari / INFN, Cagliari, Italy 6) CERN, Geneva, Switzerland 7) Laboratório de Instrumentação e F́ısica de Part́ıculas (LIP), Lisbon, Portugal 8) Institute for Nuclear Research (INR), Moscow, Russia 9) Institut de Physique Nucléaire de Orsay (IPNO), Université Paris-Sud, IN2P3-CNRS, Orsay, France 10) Laboratoire de Physique Nucléaire des Hautes Energies (LPNHE), Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 11) Università di Torino / INFN, Torino, Italy 12) Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard, IN2P3-CNRS, Villeurbanne, France 13) Yerevan Physics Institute (YerPhI), Yerevan, Armenia a) Also at UCEH, Universidade do Algarve, Faro, Portugal b) Also at IST, Universidade Técnica de Lisboa, Lisbon, Portugal c) Now at CERN, Geneva, Switzerland d) Now at FPNT, University of Mining and Metallurgy, Cracow, Poland e) On leave of absence from YerPhI, Yerevan, Armenia f) Also at University of Wuppertal, Wuppertal, Germany

The centrality dependence of the mean charged-particle multiplicity as a function of pseudorapidity is measured in approximately 1 mu b(-1) of proton-lead collisions at a nucleon-nucleon centre-of-mass energy of root s(NN) = 5.02 TeV using the ATLAS detector at the Large Hadron Collider. Charged particles with absolute pseudorapidity less than 2.7 are reconstructed using the ATLAS pixel detector. The p + Pb collision centrality is characterised by the total transverse energy measured in the Pb-going direction of the forward calorimeter. The charged-particle pseudorapidity distributions are found to vary strongly with centrality, with an increasing asymmetry between the proton-going and Pb-going directions as the collisions become more central. Three different estimations of the number of nucleons participating in the p + Pb collision have been carried out using the Glauber model as well as two Glauber-Gribov inspired extensions to the Glauber model. Charged-particle multiplicities per participant pair are found to vary differently for these three models, highlighting the importance of including colour fluctuations in nucleon-nucleon collisions in the modelling of the initial state of p + Pb collisions.

The ATLAS experiment has performed extensive searches for the electroweak production of charginos, neutralinos and staus. This article summarizes and extends the search for electroweak supersymmetry with new analyses targeting scenarios not covered by previously published searches. New searches use vector-boson fusion production, initial-state radiation jets, and low-momentum lepton final states, as well as multivariate analysis techniques to improve the sensitivity to scenarios with small mass splittings and low-production cross-sections. Results are based on 20 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$=8 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. The new and existing searches are combined and interpreted in terms of 95% confidence-level exclusion limits in simplified models, where a single production process and decay mode is assumed, as well as within phenomenological supersymmetric models.

A search for supersymmetry in hadronic final states with highly boosted W bosons and b jets is presented, focusing on compressed scenarios. The search is performed using proton-proton collision data at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.7 inverse femtobarns. Events containing candidates for hadronic decays of boosted W bosons are identified using jet substructure techniques, and are analyzed using the razor variables M[R] and R^2, which characterize a possible signal as a peak on a smoothly falling background. The observed event yields in the signal regions are found to be consistent with the expected contributions from standard model processes, which are predicted using control samples in the data. The results are interpreted in terms of gluino-pair production followed by their exclusive decay into top squarks and top quarks. The analysis excludes gluino masses up to 1.1 TeV for light top squarks decaying solely to a charm quark and a neutralino, and up to 700 GeV for heavier top squarks decaying solely to a top quark and a neutralino.

A search is presented for a high-mass Higgs boson in the [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] decay modes using the ATLAS detector at the CERN Large Hadron Collider. The search uses proton-proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb[Formula: see text]. The results of the search are interpreted in the scenario of a heavy Higgs boson with a width that is small compared with the experimental mass resolution. The Higgs boson mass range considered extends up to [Formula: see text] for all four decay modes and down to as low as 140 [Formula: see text], depending on the decay mode. No significant excess of events over the Standard Model prediction is found. A simultaneous fit to the four decay modes yields upper limits on the production cross-section of a heavy Higgs boson times the branching ratio to [Formula: see text] boson pairs. 95 % confidence level upper limits range from 0.53 pb at [Formula: see text] GeV to 0.008 pb at [Formula: see text] GeV for the gluon-fusion production mode and from 0.31 pb at [Formula: see text] GeV to 0.009 pb at [Formula: see text] GeV for the vector-boson-fusion production mode. The results are also interpreted in the context of Type-I and Type-II two-Higgs-doublet models.

Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb$^{-1}$ of $pp$ collisions produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector. Cross sections are obtained from measured $H \rightarrow \gamma \gamma$ and $H \rightarrow ZZ ^{*}\rightarrow 4\ell$ event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be $\sigma_{pp \to H} = 33.0 \pm 5.3 \, ({\rm stat}) \pm 1.6 \, ({\rm sys}) \mathrm{pb}$. The measurements are compared to state-of-the-art predictions.

Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh -> bb tau tau, gamma gamma WW* final states using 20.3 fb(-1) of pp collision data at a center-of-m ...

Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at √(s)NN=2.76  TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14  nb(-1), respectively. The jets are identified with the anti-k(t) algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32<p(T)<500  GeV and absolute rapidity |y|<2.1 and as a function of collision centrality. The nuclear modification factor R(AA) is evaluated, and jets are found to be suppressed by approximately a factor of 2 in central collisions compared to pp collisions. The R(AA) shows a slight increase with p(T) and no significant variation with rapidity.

Using a data sample of 106 million $\psi(3686)$ events collected with the BESIII detector operated at the BEPCII storage ring, we study for the first time the decay $\chi_{cJ}\to\phi K^{0}_S K^{\pm}\pi^{\mp}$ and $\chi_{cJ}\to\phi K^{+} K^{-}\pi^{0}$ in the E1 radiative transition $\psi(3686)\to\gamma\chi_{cJ}$. The decays are dominated by the three-body decay $\chi_{cJ}\to \phi K^*(892)\bar{K}$. We measure branching fractions for this reaction via the neutral and charged $K^*(892)$ and find them consistent with each other within the expectation of isospin symmetry. In the $K\bar{K}\pi$ invariant mass distribution a structure near the $K^*(892)\bar{K}$ mass threshold is observed, and the corresponding mass and width are measured to be $1412\pm4(\mathrm{stat.})\pm8(\mathrm{sys.}) \mathrm{MeV}/c^2$ and $\Gamma$ = $84\pm12(\mathrm{stat.})\pm40(\mathrm{sys.}) \mathrm{MeV}$, respectively. The observed state favors an assignment to the $h_1(1380)$, considering its possible $J^{PC}$ and comparing its mass, width and decay mode to those reported in the Particle Data Group.

presented by Albert Romana for the NASO Collaboration M.C. Abreu6•0, B . Alessandro1 1 , C. Alexa3, R. Amaldi11 , J. Astruc8 , M. Atayan13, C. Baglin1 , A . Baldit2, M. Bedjidian12, F . Bellaiche12, S . Beoie11 , V . Boldea3, P. Bordalo8·b, A . Bussiilre1, V. Capony1 , L. Casagrande8, J. Castor2, T. Chambon2, B. Chaurand9, I. Chevrot2, B. Cheynis12, E. Chiavassa1 1 , C. Cicalo4 , M.P. Comets8, S. Constantinescu3, J. Cruz8 , A. De Falco\ N. De Marco11, G. Dellacasa11·<, A. Devaux2, S. Dita3, 0. Drapier12, B. Espagnon2, J.Fargeix2, S.N. Filippov7, F. Fleuret9 , P. Force2, M. Gallio11 , Y.K. Gavrilov7, C. Gerschel8, P. Giubellino11, :M.B. Golubeva7, M. Gonin9 , A.A. Grigorian13, J.Y. Grossiord12, F.F. Guber7, A. Guichard12, H. Gulkanian13, R. Hakobyan13, R. Haroutunian12, M. ldzik11•d, D. Jouan8, T.L. Karavitcheva7, L. Kluberg9, A.B. Kurepin7, Y. Le Bornec8, C. Louren�o5, M. :Mac Cormick8, P. ::vlacciotta4 , A. Marzari-Chiesa11 , M . Masera1 1 , A . :Masoni4 , S . Mehrabian13 , S. Mourgues2, A . :Musso11, F . Ohlsson-:Malek12·•, P. Petiau9, A. Piccotti1 1 , J.R. Pizzi12, W.L. Prado Da Silva11·f, G. Puddu4, C. Quintans8, C. Racca10, L. Ramello11 ·c , S. Ramos8•b, P. Rato-Mendes11 , L. Riccati1 1 , A. Romana9, S. Sartori1 1 , P. Satumini2 , E. Scomparin5·9, S. Serci4 , R. Shahoyan8·h, S. Silva8, C. Soave11 , P. Sonderegger5·b, X. Tarrago8, P. Temnikov4 , N.S. Topilskaya7, G.L. Usai4, C. Vale8, E. Vercellin11 and N. Willis8 • 1 LAPP, CNRS-IN2P3, Annecy-LeVieux, France; 2 LPG, Uni11ersite Blaise Pascal and CNRS-IN2P3, Aubiere, France; 3 !FA, Bucharest, Romania; 4 Unillersitd di Cagliari and INFN, Cagliari, Italy; 5 CERN, Gene11a, Switzerland; 8 LIP, Lisbon, Portugal; 7 INR, Moscow, Russia; 8 JPN, Uni11ersite Paris-Sud and CNRS-IN2P3 , Orsay, France; 9 LPNHE, Ecole Polytechnique and CNRS-IN2P3 , Palaiseau, France; 10 IReS, Universite Louis Pasteur and CNRS-IN2P3, Strasbourg, France; 1 14 Uni11ersita di Torino and INFN, Torino, Italy; 12 JPN, Uni11ersite Claude Bernard and CNRS-IN2P3 , Villeurbanne, France; 13 YerPhi, Yerevan, Armenia. • also at FCUL, Unillersidade de Lisboa, Lisbon,Portugal; b also at !ST, Universidade Tecnica de Lisboa, Lisbon,Portugal; c Dipartimento di Scienze e Tecnologie Avanzate, II Facolta di Scienze, Alessandria, Italy; d now at Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, Cracow, Poland; • now at !SN, Uni11ersite Joseph Fourier and CNRS-IN2P3 , Grenoble, France; I now at UERJ, Rio de Janeiro, Brazil; 9 on leave of absence from INFN Torino, Italy; h on lea11e of absence from YerPhi, Yerevan, Armenia.

A search for the decay to a pair of new particles of either the 125 GeV Higgs boson (h) or a second charge parity (CP)-even Higgs boson (H) is presented. The data set corresponds to an integrated luminosity of 20.3 fb−1 of pp collisions at √s=8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (a). One of the two a bosons is required to decay to two muons while the other is required to decay to two τ leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 to 50 GeV. Upper limits are placed on the production of h→aa relative to the standard model gg→h production, assuming no coupling of the a boson to quarks. The most stringent limit is placed at 3.5% for ma=3.75 GeV. Upper limits are also placed on the production cross section of H→aa from 2.33 to 0.72 pb, for fixed ma=5 GeV with mH ranging from 100 to 500 GeV.Received 8 May 2015DOI:https://doi.org/10.1103/PhysRevD.92.052002This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.© 2015 CERN, for the ATLAS Collaboration

The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton-proton collision data with a centre-of-mass energy of [Formula: see text] TeV corresponding to an integrated luminosity of [Formula: see text][Formula: see text]. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-[Formula: see text] algorithm with distance parameters [Formula: see text] or [Formula: see text], and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a [Formula: see text] boson, for [Formula: see text] and pseudorapidities [Formula: see text]. The effect of multiple proton-proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 % is found in the central calorimeter region ([Formula: see text]) for jets with [Formula: see text]. For central jets at lower [Formula: see text], the uncertainty is about 3 %. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton-proton collisions and test-beam data, which also provide the estimate for [Formula: see text] TeV. The calibration of forward jets is derived from dijet [Formula: see text] balance measurements. The resulting uncertainty reaches its largest value of 6 % for low-[Formula: see text] jets at [Formula: see text]. Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5-3 %.