2,700 research outputs found
From Popular to Unpopular Education? The Open-Air School(s) of ‘Pont-Rouge’, Roubaix (1921-1978)
Broken symmetry of row switching in 2D Josephson junction arrays
We present an experimental and theoretical study of row switching in
two-dimensional Josephson junction arrays. We have observed novel dynamic
states with peculiar percolative patterns of the voltage drop inside the
arrays. These states were directly visualized using laser scanning microscopy
and manifested by fine branching in the current-voltage characteristics of the
arrays. Numerical simulations show that such percolative patterns have an
intrinsic origin and occur independently of positional disorder. We argue that
the appearance of these dynamic states is due to the presence of various
metastable superconducting states in arrays.Comment: 4 Pages, 6 Figure
Simulation of the CMS Resistive Plate Chambers
The Resistive Plate Chamber (RPC) muon subsystem contributes significantly to
the formation of the trigger decision and reconstruction of the muon trajectory
parameters. Simulation of the RPC response is a crucial part of the entire CMS
Monte Carlo software and directly influences the final physical results. An
algorithm based on the parametrization of RPC efficiency, noise, cluster size
and timing for every strip has been developed. Experimental data obtained from
cosmic and proton-proton collisions at TeV have been used for
determination of the parameters. A dedicated validation procedure has been
developed. A good agreement between the simulated and experimental data has
been achieved.Comment: to be published in JINS
High rate, fast timing Glass RPC for the high {\eta} CMS muon detectors
The HL-LHC phase is designed to increase by an order of magnitude the amount
of data to be collected by the LHC experiments. To achieve this goal in a
reasonable time scale the instantaneous luminosity would also increase by an
order of magnitude up to . The region of the forward
muon spectrometer () is not equipped with RPC stations. The
increase of the expected particles rate up to (including a
safety factor 3) motivates the installation of RPC chambers to guarantee
redundancy with the CSC chambers already present. The actual RPC technology of
CMS cannot sustain the expected background level. The new technology that will
be chosen should have a high rate capability and provides a good spatial and
timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity
(LR) glass is proposed to equip at least the two most far away of the four high
muon stations of CMS. First the design of small size prototypes and
studies of their performance in high-rate particles flux is presented. Then the
proposed designs for large size chambers and their fast-timing electronic
readout are examined and preliminary results are provided.Comment: 14 pages, 11 figures, Conference proceeding for the 2016 Resistive
Plate Chambers and Related Detector
Measurement of jet multiplicity distributions in [Formula: see text] production in pp collisions at [Formula: see text].
The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7[Formula: see text] at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton+jets decay channels using data corresponding to an integrated luminosity of 5.0[Formula: see text]. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the [Formula: see text] production is determined as a function of the additional jet multiplicity in the lepton+jets channel. Furthermore, the fraction of events with no additional jets is measured in the dilepton channel, as a function of the threshold on the jet transverse momentum. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed
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Measurement of WZ and ZZ production in pp collisions at [Formula: see text] in final states with b-tagged jets.
Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at [Formula: see text][Formula: see text] in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either [Formula: see text], [Formula: see text] or [Formula: see text], [Formula: see text], or [Formula: see text]). The results are based on data corresponding to an integrated luminosity of 18.9 fb[Formula: see text] collected with the CMS detector at the Large Hadron Collider. The measured cross sections, [Formula: see text] and [Formula: see text], are consistent with next-to-leading order quantum chromodynamics calculations
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Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at [Formula: see text].
A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at [Formula: see text] is presented. The data sample corresponds to an integrated luminosity of 5.0[Formula: see text] collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25[Formula: see text] respectively, in the pseudorapidity range [Formula: see text], [Formula: see text] and with an angular separation [Formula: see text], is [Formula: see text][Formula: see text]. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics
Possible first order transition in the two-dimensional Ginzburg-Landau model induced by thermally fluctuating vortex cores
We study the two-dimensional Ginzburg-Landau model of a neutral superfluid in
the vicinity of the vortex unbinding transition. The model is mapped onto an
effective interacting vortex gas by a systematic perturbative elimination of
all fluctuating degrees of freedom (amplitude {\em and} phase of the order
parameter field) except the vortex positions. In the Coulomb gas descriptions
derived previously in the literature, thermal amplitude fluctuations were
neglected altogether. We argue that, if one includes the latter, the vortices
still form a two- dimensional Coulomb gas, but the vortex fugacity can be
substantially raised. Under the assumption that Minnhagen's generic phase
diagram of the two- dimensional Coulomb gas is correct, our results then point
to a first order transition rather than a Kosterlitz-Thouless transition,
provided the Ginzburg-Landau correlation length is large enough in units of a
microscopic cutoff length for fluctuations. The experimental relevance of these
results is briefly discussed. [Submitted to J. Stat. Phys.]Comment: 36 pages, LaTeX, 6 figures upon request, UATP2-DB1-9
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