Search for Yukawa production of a light neutral Higgs boson at LEP
Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in the mass range of 4–12 GeV has been performed in the Yukawa process \(\mathrme^+ \mathrme^-\rightarrow \mathrm{b}\bar{\mathrm{b}}\mathrm{A}/\mathrm{h}\rightarrow\mathrm{b} \bar{\mathrm{b}}\tau^+\tau^-\), using the data collected by the OPAL detector at LEP between 1992 and 1995 in \(\mathrme^+ \mathrme^-\) collisions at about 91 GeV centre-of-mass energy. A likelihood selection is applied to separate background and signal. The number of observed events is in good agreement with the expected background. Within a CP-conserving 2HDM type II model the cross-section for Yukawa production depends on \(\xi^{\mathrm{A}}_d=|\tan\beta|\) and \(\xi^{\mathrm{h}}_d=|\sin\alpha/\cos\beta|\) for the production of the CP-odd A and the CP-even h, respectively, where \(\tan\beta\) is the ratio of the vacuum expectation values of the Higgs doublets and \(\alpha\) is the mixing angle between the neutral CP-even Higgs bosons. From our data 95% C.L. upper limits are derived for \(\xi^{\mathrm{A}}_d\) within the range of 8.5 to 13.6 and for \(\xi^{\mathrm{h}}_d\) between 8.2 to 13.7, depending on the mass of the Higgs boson, assuming a branching fraction into \(\tau^+\tau^-\) of 100%. An interpretation of the limits within a 2HDM type II model with Standard Model particle content is given. These results impose constraints on several models that have been proposed to explain the recent BNL measurement of the muon anomalous magnetic moment.

title: Results of the first integration test of the CMS drift tubes muon trigger
abstract: Two drift tubes (DTs) chambers of the CMS muon barrel system were exposed to a 40 MHz bunched muon beam at the CERN SPS, and for the first time the whole CMS Level-1 DTs-based trigger system chain was tested. Data at different energies and inclination angles of the incident muon beam were collected, as well as data with and without an iron absorber placed between the two chambers, to simulate the electromagnetic shower development in CMS. Special data-taking runs were dedicated to test for the first time the Track Finder system, which reconstructs track trigger candidates by performing a proper matching of the muon segments delivered by the two chambers. The present paper describes the results of these measurements.

title: The CMS muon barrel drift tubes system commissioning
abstract: The CMS muon barrel drift tubes system has been recently fully installed and commissioned in the experiment. The performance and the current status of the detector are briefly presented and discussed.

title: Tests of models of color reconnection and a search for glueballs using gluon jets with a rapidity gap
abstract: Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from hadronic Z(0) decay events produced in e (+) e(-) annihilations. A subsample of these jets is identified which exhibits a large gap in the rapidity distribution of particles within the jet. After imposing the requirement of a rapidity gap, the gluon jet purity is 86%. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We use our data to test three QCD models which include a simulation of color reconnection: one in the Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and that the description of inclusive Z(0) data is significantly degraded in this case. We conclude that color reconnection as implemented by these two models is disfavored. The signal from the Herwig color reconnection model is less clear and we do not obtain a definite conclusion concerning this model. In a separate study, we follow recent theoretical suggestions and search for glueball-like objects in the leading part of the gluon jets. No clear evidence is observed for these objects.

title: Alignment of the CMS Silicon Tracker during Commissioning with Cosmic Rays
abstract: This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOP

title: Constraints on anomalous quartic gauge boson couplings from nu anti-nu gamma gamma and q anti-q gamma gamma events at LEP2
abstract: Anomalous quartic couplings between the electroweak gauge bosons may contribute to the vv gamma gamma and qq gamma gamma final states produced in e+e- collisions. This analysis uses the LEP2 OPAL data sample at centre-of-mass energies up to 209 GeV. Event selections identify vv gamma gamma and qq gamma gamma events in which the two photons are reconstructed within the detector acceptance. The cross-section for the process e+e- -> qq gamma gamma is measured. Averaging over all energies, the ratio of the observed e+e- -> qq gamma gamma cross-section to the Standard Model expectation is R(data/SM) = 0.92 +- 0.07 +- 0.04 where the errors represent the statistical and systematic uncertainties respectively. The vv gamma gamma and qq gamma gamma data are used to constrain possible anomalous W+W- gamma gamma and ZZ gamma gamma couplings. Combining with previous OPAL results from the W+W- gamma final state, the 95% confidence level limits on the anomalous coupling parameters aoz, acz, aow and acw are found to be: 
-0.007 GeV^-2 < aoz/Lambda^2 < 0.023 GeV^-2 -0.029 GeV^-2 < acz/Lambda^2 < 0.029 GeV^-2 -0.020 GeV^-2 < aow/Lambda^2 < 0.020 GeV^-2 -0.052 GeV^-2 < acw/Lambda^2 < 0.037 GeV^-2 where Lamdba is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented.

title: HPD: new UV detector for Imaging Air Cherenkov Telescopes
abstract: AbstractWeproposetouseanewlargephotocathodicareaUVRb 2 TeHPDdevelopedatCERN(TOMcollaboration)asadetectorwellsuitedforIACTexperiments.SomeaspectsofUVatmospherictransmissionarepresented.r 2003ElsevierScienceB.V.Allrightsreserved.  IACT;UVCherenkovlight;HPD 1. IntroductionCLUE[1]isanImagingAtmosphericCheren-kovTelescope(IACT)array(9telescopes)locatedatLaPalmaIsland(2.2kmasl).TheobservationoftheUVCherenkovlightoftheatmosphericshowersproducedbyVHE(10GeV–l0TeV)cos-mic-andg-rays,allowsIACTexperimentstohavelongduty-cycle,totakemeasurementinbrightlyskyzones(likeMilkyWayCenter)andtopointdirectlytothemoon.CLUE[2]hasdetectedtheclassA(T.Weekescatalog)extragalacticVHEsourceAGNMkn421at17s signiﬁcancelevel,using a Multi Wire Proportional Chamber(MWPC)intherange190–220nmasUVdetector.ThelightyieldbyVHEatmosphericshowersissuppressedbytheozonelayersothatthenumberofsignalphotonsonthemirrorfocalplaneisrelatively low (C80ph/m 2 @2.2kmasl). We areinvestigatingthepossibilitytouseanewlargephotocathodicareaUVRb