The Scientific and Technical Research Council of Turkey, and Turkish Atomic Energy Authorit

Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at √ s = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between −2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN ch /dη| |η|<0.5 , are 3.48 ± 0.02 (stat.) ± 0.13 (syst.) and 4.47 ± 0.04 (stat.) ± 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in pp and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.

A study of vector boson scattering in pp collisions at a center-of-mass energy of 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.4 fb −1 collected with the CMS detector. Candidate events are selected with exactly two leptons of the same charge, two jets with large rapidity separation and high dijet mass, and moderate missing transverse energy. The signal region is expected to be dominated by electroweak same-sign W-boson pair production. The observation agrees with the standard model prediction. The observed significance is 2.0 standard deviations, where a significance of 3.1 standard deviations is expected based on the standard model. Cross section measurements for W AE W AE and WZ processes in the fiducial region are reported. Bounds on the structure of quartic vector-boson interactions are given in the framework of dimension-eight effective field theory operators, as well as limits on the production of doubly charged Higgs bosons.

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Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of √ s = 0.9, 2.36, and 7 TeV, in five pseudorapidity ranges from |η| < 0.5 to |η| < 2.4. The data were collected with the minimum-bias trigger of the CMS experiment during the LHC commissioning runs in 2009 and the 7 TeV run in 2010. The multiplicity distribution at √ s = 0.9 TeV is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with √ s is underestimated by most event generators. The average transverse momentum as a function of the multiplicity is also presented. The measurement of higher-order moments of the multiplicity distribution confirms the violation of Koba-Nielsen-Olesen scaling that has been observed at lower energies. Keywords: Hadron-Hadron ScatteringOpen Access, Copyright CERN, for the benefit of the CMS Collaboration The CMS collaboration 21 IntroductionThe charged hadron multiplicity, or number of primary charged hadrons, n, is a basic global observable characterising final states in high-energy-collision processes. The multiplicity distribution, P n , is the probability to produce n charged hadrons in an event, either in full phase space or in restricted phase space domains. In this paper we report measurements of P n in non-single-diffractive [1] proton-proton collisions, at centre-of-mass energies √ s = 0.9, 2.36, and 7 TeV at the Large Hadron Collider (LHC) [2]. The measurements are based on events recorded by the Compact Muon Solenoid (CMS) [3] experiment, using a minimumbias trigger.Energy-momentum and charge conservation significantly influence the multiplicity distribution for the full phase space. The distribution in restricted phase space, which is less affected by such constraints, is expected to be a more sensitive probe of the underlying dynamics and can be used to better constrain phenomenological models. Comprehensive reviews on the subject can be found in [1,4,5]. The measurements described in this paper are performed for intervals of increasing extent in pseudorapidity from |η| < 0.5 up to |η| < 2.4, where η is defined as −ln[tan(θ/2)], and θ is the polar angle of the particle with respect to -1 - JHEP01(2011)079the counterclockwise beam direction. In these measurements primary charged hadrons are defined as all charged hadrons produced in the interaction, including the products of the decays of objects with life-time less than 10 −10 seconds; products of longer-lived particles, such as K 0 S and Λ, and hadrons originating from secondary interactions are excluded. Independent emission of single particles yields a Poissonian P n . Deviations from this shape, therefore, reveal correlations. These correlations are predominantly short range in rapidity, attributed to cluster decays, and reflect local conservation of quantum numbers in the hadronisation process. In hadron-hadron interactions, additional large long-range rapidity correlations are observed, wh...