First beam operation of the CMS calorimeter trigger synchronization boards
The CMS experiment uses information from its electromagnetic and hadronic calorimeters and muon detectors to decide whether to readout the whole detector. For such a task to be successful, all trigger primitives pushed through the trigger decision tree must be flawlessly aligned in time for operation at 40 MHz. Both calorimeters in CMS use the Synchronization Link Board for this purpose. In this article we report on the results of tests of this board using realistic beam conditions, which demonstrate the soundness of the adopted architecture and synchronization principle.

title: Alignment of the CMS muon system with cosmic-ray and beam-halo muons
abstract: The CMS muon system has been aligned using cosmic-ray muons collected in 2008 and beam-halo muons from the 2008 LHC circulating beam tests. After alignment, the resolution of the most sensitive coordinate is 80 microns for the relative positions of superlayers in the same barrel chamber and 270 microns for the relative positions of endcap chambers in the same ring structure. The resolution on the position of the central barrel chambers relative to the tracker is comprised between two extreme estimates, 200 and 700 microns, provided by two complementary studies. With minor modifications, the alignment procedures can be applied using muons from LHC collisions, leading to additional significant improvements.

title: Performance of tau-lepton reconstruction and identification in CMS
abstract: The performance of tau-lepton reconstruction and identification algorithms is studied using a data sample of proton-proton collisions at sqrt(s)=7 TeV, corresponding to an integrated luminosity of 36 inverse picobarns collected with the CMS detector at the LHC. The tau leptons that decay into one or three charged hadrons, zero or more short-lived neutral hadrons, and a neutrino are identified using final-state particles reconstructed in the CMS tracker and electromagnetic calorimeter. The reconstruction efficiency of the algorithms is measured using tau leptons produced in Z-boson decays. The tau-lepton misidentification rates for jets and electrons are determined.

title: Search for the standard model Higgs boson produced in association with a top-quark pair in pp collisions at the LHC
abstract: A bstractA search for the standard model Higgs boson produced in association with a top-quark pair is presented using data samples corresponding to an integrated luminosity of 5.0 fb−1 (5.1 fb−1) collected in pp collisions at the center-of-mass energy of 7 TeV (8 TeV). Events are considered where the top-quark pair decays to either one lepton+jets $ \left( {\mathrm{t}\overline{\mathrm{t}}\to \ell \nu \mathrm{q}\overline{\mathrm{q}}\prime \mathrm{b}\overline{\mathrm{b}}} \right) $ or dileptons $ \left( {\mathrm{t}\overline{\mathrm{t}}\to {\ell^{+}}\nu {\ell^{-}}\overline{\nu}\mathrm{b}\overline{\mathrm{b}}} \right) $, ℓ being an electron or a muon. The search is optimized for the decay mode $ \mathrm{H}\to \mathrm{b}\overline{\mathrm{b}} $. The largest background to the $ \mathrm{t}\overline{\mathrm{t}}\mathrm{H} $ signal is top-quark pair production with additional jets. Artificial neural networks are used to discriminate between signal and background events. Combining the results from the 7 TeV and 8 TeV samples, the observed (expected) limit on the cross section for Higgs boson production in association with top-quark pairs for a Higgs boson mass of 125 GeV is 5.8 (5.2) times the standard model expectation.

title: Data filtering in the readout of the CMS Electromagnetic Calorimeter
abstract: For an efficient data taking, the Electromagnetic Calorimeter data of the CMS experiment must be limited to 10% of the full event size (1MB). Other requirements limit the average data size to 2kB per data acquisition link. These conditions imply a reduction factor of close to twenty on the data collected. The data filtering in the readout of the Electromagnetic Calorimeter detector is discussed. Test beam data are used to study the digital filtering applied in the readout channels and a full detector simulation allows to estimate the energy thresholds to achieve the desired data suppression factor.

title: Performance of the CMS Drift Tube Chambers with Cosmic Rays
abstract: Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 microns, and a nearly 100% efficiency for the drift tube cells. The resolution of the track direction measured in the bending plane is about 1.8 mrad, and the efficiency to reconstruct a segment in a single chamber is higher than 99%. The CMS simulation of cosmic rays reproduces well the performance of the barrel muon detector.

title: Testbeam studies of production modules of the ATLAS tile calorimeter
abstract: We report test beam studies of 11% of the production ATLAS Tile Calorimeter modules. The modules were equipped with production front-end electronics and all the calibration systems planned for the final detector. The studies used muon, electron and hadron beams ranging in energy from 3 to 350 GeV. Two independent studies showed that the light yield of the calorimeter was ∼ 70 pe / GeV , exceeding the design goal by 40%. Electron beams provided a calibration of the modules at the electromagnetic energy scale. Over 200 calorimeter cells the variation of the response was 2.4%. The linearity with energy was also measured. Muon beams provided an intercalibration of the response of all calorimeter cells. The response to muons entering in the ATLAS projective geometry showed an RMS variation of 2.5% for 91 measurements over a range of rapidities and modules. The mean response to hadrons of fixed energy had an RMS variation of 1.4% for the modules and projective angles studied. The response to hadrons normalized to incident beam energy showed an 8% increase between 10 and 350 GeV, fully consistent with expectations for a noncompensating calorimeter. The measured energy resolution for hadrons of σ / E = 52.9 % / E ⊕ 5.7 % was also consistent with expectations. Other auxiliary studies were made of saturation recovery of the readout system, the time resolution of the calorimeter and the performance of the trigger signals from the calorimeter.

title: Spontaneous breaking of global symmetries and invisible triplet majoron
abstract: We show that axions and majorons can be a natural outcome in a 3-3-1 type model with right-handed neutrinos. We implement the breaking of their associated symmetries, Peccei-Quinn and Lepton number respectively, and study the phenomenological consequences. The main result of this work is that our majoron is invisible even though it belongs to a triplet representation.

title: Latest results and prospects of the CERN Axion Solar Telescope
abstract: The CERN Axion Solar Telescope (CAST) experiment searches for axions from the Sun converted into few keV photons via the inverse Primakoff effect in the high magnetic field of a superconducting Large Hadron Collider (LHC) decommissioned test magnet. After results obtained with vacuum in the magnet pipes (phase I of the experiment) as well as with 4He the collaboration is now immersed in the data taking with 3He, to be finished in 2011. The status of the experiment will be presented, including a preliminary exclusion plot of the first 3He data. CAST is currently sensitive to realistic QCD axion models at the sub-eV scale, and with axion-photon couplings down to the ~ 2 × 10−10 GeV−1, compatible with solar life limits. Future plans include revisiting vaccuum and 4He configurations with improved sensitivity, as well as possible additional search for non-standard signals from chamaleons, paraphotons or other WISPs. For the longer term, we study the feasibility of an altogether improved version of the axion helioscope concept, with a jump in sensitivity of about one order of magnitude in gaγ beyond CAST.

title: Exploring the Infrared Gluon and Ghost Propagators Using Large Asymmetric Lattices
abstract: We report on the infrared limit of the quenched lattice Landau gauge gluon propagator computed from large asymmetric lattices. In particular, the compatibility of the pure power law infrared solution (q2)2k of the Dyson-Schwinger equations is investigated and the exponent k is measured. The lattice data favours k ~ 0.52, which would imply a vanishing zero momentum gluon propagator as predicted by the Kugo-Ojima confinement mechanism and the Zwanziger horizon condition. Results for the ghost propagator and for the running coupling constant are shown.

title: Online neural trigger for optimizing data acquisition during particle beam calibration tests with calorimeters
abstract: For LHC, the hadronic calorimetry of the ATLAS detector is performed by Tilecal, a scintillating tile calorimeter. For calibration purposes, a fraction of the Tilecal modules is placed in particle beam lines. Despite beam high quality, experimental beam contamination is observed and this masks the actual performance of the calorimeter. For optimizing the calibration task, an online neural particle classifier was developed for Tilecal. Envisaging a neural trigger for incoming particles, a neural process runs integrated to the data acquisition task and performs online training for particle identification. The neural classification performance is evaluated by correlating the neural response to classical methodology, confirming an ability for outsider identification at levels as high as 99.3%.