The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for pair-produced charged Higgs bosons in the framework of Two Higgs Doublet Models (2HDMs). The data of the four experiments ...have been statistically combined. The results are interpreted within the 2HDM for Type I and Type II benchmark scenarios. No statistically significant excess has been observed when compared to the Standard Model background prediction, and the combined LEP data exclude large regions of the model parameter space. Charged Higgs bosons with mass below 80
(Type II scenario) or 72.5
(Type I scenario, for pseudo-scalar masses above 12
) are excluded at the 95 % confidence level.
Bunched beam test of the CMS drift tubes local muon trigger Arce, P.; Bellato, M.; Benettoni, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2004, Letnik:
534, Številka:
3
Journal Article
Recenzirano
The 40
MHz bunched muon beam set up at CERN was used in May 2003 to make a full test of the drift tubes local muon trigger. The main goal of the test was to prove that the integration of the various ...devices located on a muon chamber was adequately done both on the hardware and software side of the system. Furthermore the test provided complete information about the general performance of the trigger algorithms in terms of efficiency and noise. Data were collected with the default configuration of the trigger devices and with several alternative configurations at various angles of incidence of the beam. Tests on noise suppression and di-muon trigger capability were performed.
The CMS experiment is currently developing a computing system capable of serving, processing and archiving the large number of events that will be generated when the CMS detector starts taking data. ...During 2004 CMS undertook a large scale data challenge to demonstrate the ability of the CMS computing system to cope with a sustained data-taking rate equivalent to 25% of startup rate. Its goals were: to run CMS event reconstruction at CERN for a sustained period at 25 Hz input rate; to distribute the data to several regional centers; and enable data access at those centers for analysis. Grid middleware was utilized to help complete all aspects of the challenge. To continue to provide scalable access from anywhere in the world to the data, CMS is developing a layer of software that uses Grid tools to gain access to data and resources, and that aims to provide physicists with a user friendly interface for submitting their analysis jobs. This paper describes the data challenge experience with Grid infrastructure and the current development of the CMS analysis system.
This Letter describes a direct search for pair produced magnetic monopoles in e+e− collisions. The analysis is based on 62.7 pb−1 of data collected with the OPAL detector at an average centre-of-mass ...energy of s=206.3 GeV. The monopole signal was assumed to be characterized by two back-to-back particles with an anomalously high ionization energy loss dE/dx in the tracking chambers. No evidence for production of monopoles was observed. Upper limits were obtained on the magnetic monopole pair-production cross-section (σ) in the mass range 45 GeV/c2<mM<102 GeV/c2. The average limit is σ<0.05 pb and is essentially independent of the magnetic monopole mass. The cross-section limit is derived at the 95% confidence level and is valid for spin-1/2 magnetic monopoles.
The CMS high level trigger Adam, W.; Bergauer, T.; Deldicque, C. ...
The European physical journal. C, Particles and fields,
06/2006, Letnik:
46, Številka:
3
Journal Article
Recenzirano
Odprti dostop
At the Large Hadron Collider at CERN the proton bunches cross at a rate of 40 MHz. At the Compact Muon Solenoid experiment the original collision rate is reduced by a factor of \(\mathcal{O}\) (1000) ...using a Level-1 hardware trigger. A subsequent factor of \(\mathcal{O}\) (1000) data reduction is obtained by a software-implemented high level trigger (HLT) selection that is executed on a multi-processor farm. In this review we present in detail prototype CMS HLT physics selection algorithms, expected trigger rates and trigger performance in terms of both physics efficiency and timing.
An overview is presented of the characteristics of HEP computing and its mapping to the Grid paradigm. This is followed by a synopsis of the main experiences and lessons learned by HEP experiments in ...their use of DataGrid middleware using both the EDG application testbed and the LCG production service. Particular reference is made to experiment ‘data challenges’, and a forward look is given to necessary developments in the framework of the EGEE project.
The mass and width of the W boson are measured using e+e– → W+W– events from the data sample collected by the OPAL experiment at LEP at centre-of-mass energies between 170 GeV and 209 GeV. The mass ...(mW) and width (ΓW) are determined using direct reconstruction of the kinematics of W+W– → and W+W– → events. When combined with previous OPAL measurements using W+W– → events and the dependence on of the WW production cross-section at threshold, the results are determined to be where the first error is statistical, the second systematic and the third due to uncertainties in the value of the LEP beam energy. By measuring in the channel using several different determinations of the direction of jets with differing sensitivities to soft particles, a limit is also obtained on possible final-state interactions due to colour reconnection effects inW+W– → events. The consistency of the results for the W mass and width with those inferred from other electroweak parameters provides an important test of the Standard Model of electroweak interactions.
Abstract
A search is made for charged Higgs bosons predicted by Two-Higgs-Doublet extensions of the Standard Model (2HDM) using electron-positron collision data collected by the OPAL experiment at
...$\sqrt{s}=189\mbox{--}209\ \mbox{GeV}$
, corresponding to an integrated luminosity of approximately 600 pb
−1
. Charged Higgs bosons are assumed to be pair-produced and to decay into
$\mathrm{q} \bar{\mathrm{q}}$
,
τν
τ
or AW
±
. No signal is observed. Model-independent limits on the charged Higgs-boson production cross section are derived by combining these results with previous searches at lower energies. Under the assumption
$\mathrm{BR} (\mathrm{H}^{\pm} \to \tau\nu_{\tau}) + \mathrm{BR} (\mathrm{H}^{\pm} \to \mathrm{q} \bar{\mathrm{q}}) = 1$
, motivated by general 2HDM type II models, excluded areas on the
$m_{\mathrm{H}^{\pm}} , \mathrm{BR} (\mathrm {H}^{\pm} \to \tau\nu_{\tau})$
plane are presented and charged Higgs bosons are excluded up to a mass of 76.3 GeV at 95 % confidence level, independent of the branching ratio BR(H
±
→
τν
τ
). A scan of the 2HDM type I model parameter space is performed and limits on the Higgs-boson masses
$m_{\mathrm{H}^{\pm}}$
and
m
A
are presented for different choices of tan
β
.
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