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The results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evidence for new physics beyond the standard model (SM): for example, the existence of... more
The results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evidence for new physics beyond the standard model (SM): for example, the existence of extra-dimensions, of milli-charged particles, of new light gauge bosons or of mirror particles. Mirror matter could be a relevant dark matter candidate. In this paper the setup and the results of a new experiment are presented. In a collected sample of about (6.31{+-}0.28)x10 orthopositronium decays, no evidence for invisible decays in an energy [0,80] keV was found and an upper limit on the branching ratio of orthopositronium o-Psinvisible could be set: Br(o-Psinvisible)<4.2x10(90%C.L.) Our results provide a limit on the photon mirror-photon mixing strength {<=}1.55x10(90%C.L.) and rule out particles lighter than the electron mass with a fraction Q{<=}3.4x10 of the electron charge. Furthermore, upper limits on the branching ratios for the ...
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ABSTRACT The alignment system for the muon spectrometer of the CMS detector comprises three independent subsystems of optical and analog position sensors. It aligns muon chambers with respect to each other and to the central silicon... more
ABSTRACT The alignment system for the muon spectrometer of the CMS detector comprises three independent subsystems of optical and analog position sensors. It aligns muon chambers with respect to each other and to the central silicon tracker. System commissioning at full magnetic field began in 2008 during an extended cosmic ray run. The system succeeded in tracking muon detector movements of up to 18 mm and rotations of several milliradians under magnetic forces. Depending on coordinate and subsystem, the system achieved chamber alignment precisions of 140-350 microns and 30-200 microradians, close to the precision requirements of the experiment. Systematic errors on absolute positions are estimated to be 340-590 microns based on comparisons with independent photogrammetry measurements.
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Please be patient while the object screen loads. Changez de vue : Choisir un site… UCL FUNDP FUSL FUCaM. ...
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Chatrchyan, S and Khachatryan, V and Sirunyan, AM and Adam, W and Arnold, B and Bergauer, H and Bergauer, T and Dragicevic, M and Eichberger, M and Ero, J and Friedl, M and Fruhwirth, R and Ghete, VM and Hammer, J and Hansel, S and Hoch,... more
Chatrchyan, S and Khachatryan, V and Sirunyan, AM and Adam, W and Arnold, B and Bergauer, H and Bergauer, T and Dragicevic, M and Eichberger, M and Ero, J and Friedl, M and Fruhwirth, R and Ghete, VM and Hammer, J and Hansel, S and Hoch, M and ...
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Page 1. Alignment of the CMS silicon tracker during commissioning with cosmic rays This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 JINST 5 T03009... more
Page 1. Alignment of the CMS silicon tracker during commissioning with cosmic rays This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 JINST 5 T03009 (http://iopscience.iop.org/1748-0221/5/03/T03009) ...
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ABSTRACT The CMS Collaboration conducted a month-long data taking exercise, the Cosmic Run At Four Tesla, during October-November 2008, with the goal of commissioning the experiment for extended operation. With all installed detector... more
ABSTRACT The CMS Collaboration conducted a month-long data taking exercise, the Cosmic Run At Four Tesla, during October-November 2008, with the goal of commissioning the experiment for extended operation. With all installed detector systems participating, CMS recorded 270 million cosmic ray events with the solenoid at a magnetic field strength of 3.8 T. This paper describes the data flow from the detector through the various online and offline computing systems, as well as the workflows used for recording the data, for aligning and calibrating the detector, and for analysis of the data.
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... means are consistent with the muon minimum ionizing signals measured for segments of the calorimeters in test beams [4, 6], without magnetic field, for a wide momen-tum range after taking into account magnetic field effects,... more
... means are consistent with the muon minimum ionizing signals measured for segments of the calorimeters in test beams [4, 6], without magnetic field, for a wide momen-tum range after taking into account magnetic field effects, correcting the signal for the muon path length and ...
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Page 1. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2011-066 2011/06/16 CMS-TOP-10-008 Measurement of the t-channel single top quark production cross section in pp collisions at √ s = 7 TeV The CMS Collaboration ∗... more
Page 1. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2011-066 2011/06/16 CMS-TOP-10-008 Measurement of the t-channel single top quark production cross section in pp collisions at √ s = 7 TeV The CMS Collaboration ∗ Abstract ...
... the endcaps. A similar formula is used for the τeτµ final state but with the isolation quantities based directly on tracker and calorimeter information, calculated in a cone of AR = 0.3. In this case, it is required that Irel <... more
... the endcaps. A similar formula is used for the τeτµ final state but with the isolation quantities based directly on tracker and calorimeter information, calculated in a cone of AR = 0.3. In this case, it is required that Irel < 0.15 for muons and Irel < 0.1 for electrons. ...
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... CMS-HIG-10-002 Search for Neutral MSSM Higgs Bosons Decaying to Tau ... The results are based on a data sample corre-sponding to an integrated luminosity of 36 pb−1 recorded by the CMS experiment. The search uses decays of the Higgs... more
... CMS-HIG-10-002 Search for Neutral MSSM Higgs Bosons Decaying to Tau ... The results are based on a data sample corre-sponding to an integrated luminosity of 36 pb−1 recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. ...
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... Phys. B488 (1997) 39. doi:10.1016/S0550-3213(97)00030-8. [5] JR Ellis, JL Lopez, and DV Nanopoulos, Analysis of LEP Constraints on Supersymmetric Models with a Light Gravitino, Phys. Lett. B394 (1997) 354.... more
... Phys. B488 (1997) 39. doi:10.1016/S0550-3213(97)00030-8. [5] JR Ellis, JL Lopez, and DV Nanopoulos, Analysis of LEP Constraints on Supersymmetric Models with a Light Gravitino, Phys. Lett. B394 (1997) 354. doi:10.1016/S0370-2693(97)00019-1. ...
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Page 1. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/ 2011-092 2011/07/26 CMS-HIN-10-001 Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at √ s NN = 2.76 TeV ...
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An inclusive search for same-sign top-quark pair production in pp collisions at TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 pb−1. This analysis is motivated... more
An inclusive search for same-sign top-quark pair production in pp collisions at TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 pb−1. This analysis is motivated by recent studies of reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor
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... and √ s = 7 TeV data samples, respectively. 3.2 Dijet Events The jets were reconstructed using the anti-kT jet clustering algorithm [16], with a distance parameter of 0.5. Particle flow objects [17] that combine information from all... more
... and √ s = 7 TeV data samples, respectively. 3.2 Dijet Events The jets were reconstructed using the anti-kT jet clustering algorithm [16], with a distance parameter of 0.5. Particle flow objects [17] that combine information from all the CMS sub-detectors were used as input. ...
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ABSTRACT
Page 1. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/ 2011-049 2011/04/19 CMS-QCD-10-008 Charged particle transverse momentum spectra in pp collisions at √ s = 0.9 and 7 TeV The CMS Collaboration ∗ Abstract ...
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ABSTRACT
ABSTRACT
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A search for groups of collimated muons is performed using a data sample collected by the CMS experiment at the LHC, at a centre-of-mass energy of 7TeV, and corresponding to an integrated luminosity of 35 pb−1. The analysis searches for... more
A search for groups of collimated muons is performed using a data sample collected by the CMS experiment at the LHC, at a centre-of-mass energy of 7TeV, and corresponding to an integrated luminosity of 35 pb−1. The analysis searches for production of new low-mass states decaying into pairs of muons and is designed to achieve high sensitivity to a broad
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ABSTRACT