119186828
Leading order determination of the gluon polarisation from DIS events with high-$p_T$ hadron pairs
We present a determination of the gluon polarisation Delta g/g in the nucleon, based on the longitudinal double-spin asymmetry of DIS events with Q(2) > 1 (GeV/c)(2) including a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam scattering off a polarised (LiD)-Li-6 target. The gluon polarisation is evaluated by a Neural Network approach for three intervals of the gluon momentum fraction x(g) covering the range 0.04 < x(g) < 0.27. The values obtained at leading order in QCD do not show any significant dependence on x(g). Their average is Delta g/g = 0.125 +/- 0.060 (stat.) +/- 0.063 (syst.) at average x(g) = 0.09 and a scale of mu(2) = 3 (GeV/c)(2).
55786171
Results on the primary CR spectrum and composition reconstructed with the SPHERE-2 detector
First preliminary results of the balloon-borne experiment SPHERE-2 on the all-nuclei primary cosmic rays (PCR) spectrum and primary composition are presented. The primary spectrum in the energy range 1016–5 1017 eV was reconstructed using characteristics of Vavilov-Cherenkov radiation of extensive air showers (EAS), reflected from a snow surface. Several sources of systematic uncertainties of the spectrum were analysed. A method for separation of the primary nuclei' groups based on the lateral distribution function' (LDF) steepness parameter is presented. Preliminary estimate of the mean light nuclei' fraction f30-150 at energies 3 1016–1.5 1017 eV was performed and yielded f30-150 = (21±11) %.
76657892
Hadron transverse momentum distributions in muon deep inelastic scattering at 160 GeV/c
Multiplicities of charged hadrons produced in deep inelastic muon scattering off a 6LiD target have been measured as a function of the DIS variables xBj, Q2, W2 and the final state hadron variables pT and z. The $p_{T}^{2}$ distributions are fitted with a single exponential function at low values of $p_{T}^{2}$ to determine the dependence of $\langle p_{T}^{2} \rangle$ on xBj, Q2, W2 and z. The z-dependence of $\langle p_{T}^{2} \rangle$ is shown to be a potential tool to extract the average intrinsic transverse momentum squared of partons, $\langle k_{\perp}^{2} \rangle$, as a function of xBj and Q2 in a leading order QCD parton model.
125583262
Scintillating fiber detectors using position sensitive photomultipliers
119282146
First Results of the Full-Scale OSQAR Photon Regeneration Experiment
Recent intensive theoretical and experimental studies shed light on possible new physics beyond the standard model of particle physics, which can be probed with sub-eV energy experiments. In the second run of the OSQAR photon regeneration experiment, which looks for the conversion of photon to axion (or Axion-Like Particle), two spare superconducting dipole magnets of the Large Hadron Collider (LHC) have been used. In this paper we report on first results obtained from a light beam propagating in vacuum within the 9 T field of two LHC dipole magnets. No excess of events above the background was detected and the two-photon couplings of possible new scalar and pseudo-scalar particles could be constrained.
121781142
Development of a scintillating-fibre detector for fast topological triggers in high-luminosity particle physics experiments
Abstract In the framework of the RD-17 project at CERN an extensive work is in progress on the development of scintillating-fibre detectors using position-sensitive photomultipliers. With 0.5 mm diameter fibres a spatial resolution of about 125 μm was obtained with a detection efficiency higher than 95%. The time resolution of the detector is about 600 ps, and the track position is properly digitised in real time in less than 10 ns by a peak sensing circuit. A simulation, based on experimental data, has also been performed to compare different types of front-end electronics.
23122779
Search for new physics in the multijet and missing transverse momentum final state in proton-proton collisions at √s = 7 TeV.
A search for physics beyond the standard model is performed in events with at least three jets and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of √s=7 TeV. No significant excess of events above the expected backgrounds is observed in 4.98 fb(-1) of data collected with the CMS detector at the Large Hadron Collider. The results are presented in the context of the constrained minimal supersymmetric extension of the standard model and more generically for simplified models. For the simplified models of gluino-gluino and squark-squark production, gluino masses below 1.0 TeV and squark masses below 0.76 TeV are excluded in case the lightest supersymmetric particle mass is below 200 GeV. These results significantly extend previous searches.
118218838
Search for large extra dimensions in the diphoton final state at the Large Hadron Collider
A search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected in proton-proton collisions at $ \sqrt {s} = 7 $ TeV and corresponding to an integrated luminosity of 36 pb−1. New lower limits on the effective Planck scale in the range of 1.6–2.3TeV at the 95% confidence level are set, providing the most restrictive bounds to date on models with more than two large extra dimensions.
119340162
A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL
Aims. In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type I) outburst with an average flux $F_{(5-100)}\,_{\mathrm{keV}} \sim400$ mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Methods. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. Results. The pulse period  P is measured to be 103.39315(5) s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at $E_{1}\sim 45$ keV and $E_{2}\sim 100$ keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be $B\sim 4\times 10^{12}$ G.
116999798
Search for the standard model Higgs boson produced in association with W and Z bosons in pp collisions at $ \sqrt{s}=7 $TeV
A bstractA search for the Higgs boson produced in association with a W or Z boson in proton-proton collisions at a center-of-mass energy of 7 TeV is performed with the CMS detector at the LHC using the full 2011 data sample, from an integrated luminosity of 5 fb−1. Higgs boson decay modes to ττ and WW are explored by selecting events with three or four leptons in the final state. No excess above background expectations is observed, resulting in exclusion limits on the product of Higgs associated production cross section and decay branching fraction for Higgs boson masses between 110 and 200 GeV in these channels. Combining these results with other CMS associated production searches using the same dataset in the H→ γγ and H→ b$ \overline{\mathrm{b}} $ decay modes, the cross section for associated Higgs boson production 3.3 times the standard model expectation or larger is ruled out at the 95% confidence level for a Higgs boson mass of 125 GeV.
122731585
Search for $B^0_s \to \mu^+ \mu^-$ and $B^0 \to \mu^+ \mu^-$ decays
A search for the rare decays B_s to mu+ mu- and B^0 to mu^+ mu^- is performed in pp collisions at sqrt(s) = 7 TeV, with a data sample corresponding to an integrated luminosity of 5 inverse femtobarns collected by the CMS experiment at the LHC. In both decays, the number of events observed after all selection requirements is consistent with the expectation from background plus standard model signal predictions. The resulting upper limits on the branching fractions are Br(B_s to mu^+ mu^-) < 7.7E-9 and Br(B^0 to mu^+ mu^-) < 1.8E-9 at 95% confidence level.