P. Jarry

A new beam line and detector were constructed to increase statistical precision and greatly reduce systematic uncertainty on the ratio of the CP-nonconserving parameters \ensuremath{\epsilon}'/\ensuremath{\epsilon}. Major improve- ments are discussed together with a result from a first run: \ensuremath{\epsilon}'/\ensuremath{\epsilon}=0.0032\ifmmode\pm\else\textpm\fi{}0.0028 (statistical) \ifmmode\pm\else\textpm\fi{}0.0012 (systematic). The precision is better than earlier measurements yet the result is still consistent with the superweak mechanism (which predicts zero) and that due to Kobayashi and Maskawa. Significantly more data are being collected.

We report on the multiple wavelength laser monitoring system designed for the compact muon solenoid (CMS) lead tungstate crystal calorimeter. Results are presented for the test-beam performance of the system designed to achieve ⩽0.2% relative optical transmittance inter-calibration for 75 848 lead tungstate crystals. The system cycles continuously over the calorimeter to follow each crystal's evolution under the irradiation and recovery periods foreseen during operation at the LHC.

The result of a search at the LHC for heavy stable charged particles produced in pp collisions at $ \sqrt {s} = 7\;{\text{TeV}} $ is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb−1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398GeV/c 2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c 2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.

Hadronic event shapes have been measured in proton-proton collisions at sqrt(s)=7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.

A measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations.

The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 inverse femtobarns, were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

The total e+e− annihilation onto hadron has been measured at CM energies between 33.00 and 36.72 GeV and between 38.66 and 46.78 GeV in steps of 20 and 30 MeV respectively. The average of the ratio R=σ(e+e−→hadrons)/ σ is 〈R〉=3.85±0.12 and 〈R〉=4.04±0.10 for the two energy ranges. The systematic error on 〈R〉 is 0.31. Both values are consistent with the expectation for the known coloured quarks u, d, s, c and b. No evidence was found for the production of new quarks. If the largest fluctuation in R is interpreted as a narrow resonance, it corresponds to a product of the electronic width and the hadronic branching ratio ΓeeBhad>2.9 keV at the 95% confidence level, well below the value expected for the toponium vector ground state with charge 23e. The observed number of aplanar final states rules out the continuum production of a a new heavy flavour with pointlike cross section up to a CM energy of 45.4 GeV for a quarck charge of 13e. and up to 46.6 GeV for 23e at the 95% confidence level.

Hadronic events obtained with the CELLO detector at PETRA are compared with second order QCD predictions using different models for the fragmentation of quarks and gluons into hadrons. We find that the model dependence in the determination of the strong coupling constant persists when going from first to second order QCD calculations.

An event from e+e− annihilation at √s = 43.450 GeV containing two topologically isolated energetic muons and two hadronic jets has been observed. The masses of the μ−μ, jet-jet and μ-jet combinations are all large. The expected number of such events from known processes is about 10−3.

Using the CELLO detector at PETRA a search has been made for excited leptons by studying e+e− interactions which yield l+l− γγ, l+l− γ and γγ final states, where l=e,μorτ. Good agreement with QED is observed and new limits are set on e∗, μ∗, and τ∗ production.

We have studied the reactions e+e− → e+e−, e+e− → γγ, e+e− → μ+μ−, and e+e− → τ+τ− in the centre-of-mass (CM) energy range from 39.8 to 45.2 GeV using the CELLO detector at PETRA. Upper limits on the partial widths for new spin 0 bosons with masses both within and above the energy range covered are determined. No evidence for contributions of such new particles has been observed up to the highest PETRA energies in a model independent way. Under the assumptions of recently suggested models relating the existence of spin 0 bosons to the radiative width Γτ of the Z0 we exclude such bosons at the 95% confidence level for masses below the Z0-mass if Γτ > 20 MeV.

A search is performed for the production of a massive W′ boson decaying to a top and a bottom quark. The data analysed correspond to an integrated luminosity of 19.7 fb−1 collected with the CMS detector at the LHC in proton-proton collisions at $$ \sqrt{s}=8 $$ TeV. The hadronic decay products of the top quark with high Lorentz boost from the W′ boson decay are detected as a single top flavoured jet. The use of jet substructure algorithms allows the top quark jet to be distinguished from standard model QCD background. Limits on the production cross section of a right-handed W′ boson are obtained, together with constraints on the left-handed and right-handed couplings of the W′ boson to quarks. The production of a right-handed W′ boson with a mass below 2.02 TeV decaying to a hadronic final state is excluded at 95% confidence level. This mass limit increases to 2.15 TeV when both hadronic and leptonic decays are considered, and is the most stringent lower mass limit to date in the tb decay mode.

The Cherenkov light produced by 2.8 GeVc protons in a solid NaF radiator has been detected with a CsI photocathode coupled to a multiwire proportional chamber. The measurement of the number of photoelectrons gives an estimation of the photocathode quantum efficiency.

The central tracking device of the DELPHI experiment is a time projection chamber (TPC) with an active volume of 2*1.34 m in length and 2.22 m in diameter. Since spring 1988 the TPC has undergone extensive tests in a cosmic ray setup. It has been equipped with its final readout electronics for one complete sector ( approximately 2000 channels) and has been operated since with cosmic rays as well as with the laser system and all the other calibration devices. First results indicate that the TPC behaves as expected, but more work and analysis is needed to quote final numbers. It will be installed in the LEP tunnel by early 1989. The authors describe the construction, the readout electronics, and the contribution of the TPC to the Delphi trigger. Emphasis is given to novel features which are not used in similar detectors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The reactions e+e−→μ+μ−γ and e+e−→e+e−γ have been studied with the CELLO detector at the PETRA storage ring. Data have been collected from s=14 GeV up to46.8GeV. In a Dalitz plot analysis of the data, good agreement is found with QED, except for the region Mxμγe>0.8 where the probability that QED describes the high energy data is at the percent level.

We have searched for monojet production in e+e−-annihilation with the CELLO detector operating at the highest PETRA energies. No events were found, which makes it unlikely that the recently observed monojets in pp collisions originate from unusual Z0 decays. The upper limits on monojet cross sections are compared with various models, thus yielding upper limits on the production cross sections of Higgs bosons and higgsinos.

A search for massive resonances decaying to a Z boson and a photon is performed in events with a hadronically decaying Z boson candidate, separately in light-quark and b quark decay modes, identified using jet substructure and advanced b tagging techniques. Results are based on samples of proton-proton collisions collected with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The results of the search are combined with those of a similar search in the leptonic decay modes of the Z boson, based on the same data sets. Spin-0 resonances with various widths and with masses in a range between 0.2 and 3.0 TeV are considered. No significant excess is observed either in the individual analyses or the combination. The results are presented in terms of upper limits on the production cross section of such resonances and constitute the most stringent limits to date for a wide range of masses.

The inelastic hadronic cross section in proton-lead collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample, corresponding to an integrated luminosity of 12.6 +/- 0.4 inverse nanobarns, has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the measured number of proton-lead collisions with hadronic activity produced in the pseudorapidity ranges 3<abs(eta)<5 and/or -5<abs(eta)<-3, corrected for photon-induced contributions, experimental acceptance, and other instrumental effects. The inelastic cross section is measured to be sigma[inel,pPb]=2061 +/- 3 (stat) +/- 34 (syst) +/- 72 (lum) mb. Various Monte Carlo generators, commonly used in heavy ion and cosmic ray physics, are found to reproduce the data within uncertainties. The value of sigma[inel,pPb] is compatible with that expected from the proton-proton cross section at 5.02 TeV scaled up within a simple Glauber approach to account for multiple scatterings in the lead nucleus, indicating that further net nuclear corrections are small.

A measurement of the ttbar production cross section at sqrt(s)=13 TeV is presented using proton-proton collisions, corresponding to an integrated luminosity of 2.3 inverse femtobarns, collected with the CMS detector at the LHC. Final states with one isolated charged lepton (electron or muon) and at least one jet are selected and categorized according to the accompanying jet multiplicity. From a likelihood fit to the invariant mass distribution of the isolated lepton and a jet identified as coming from the hadronization of a bottom quark, the cross section is measured to be sigma(ttbar)= 835 +/- 3 (stat) +/- 23 (syst) +/- 23 (lum) pb, in agreement with the standard model prediction. Using the expected dependence of the cross section on the pole mass of the top quark (m[t]), the value of m[t] is found to be 172.7+2.4-2.7 GeV.

Written with style, imagination and insight, and packed with interesting illustrations, this authoritative book traces the development through the ages of plays and playwriting, forms of staging, the acting profession and the role of the actor -in fact all aspects of live entertainment.

An ongoing experiment at Fermilab intends to measure the ratio of the CP violation parameters ε’/ε to a precision of .001. The experimental technique and apparatus are described. Sources of systematic error are discussed and some preliminary data from the test run in 1985 is shown. The status of the analysis is described and plans for the upcoming final data run in March 1987 are given.

This thesis reports, in its theoretical part, a method to compute vibration and vibrorotation spectra of tetrahedral molecules. The local mode model describes the stretch vibrations by means of anharmonic oscillators localized on each bond. The nearly local molecules are characterized by weak couplings between these oscillators. These couplings are treated perturbatively and the computation of the vibrational and rovibrational energies of the first excited levels is then easier. The vibration - rotation problem, more complicated than the pure vibrational one, is solved by coupling, in the Td group, a local vibrational operator with a rotational one, both having well-defined symmetries. The transition intensities are computed in the same way and by using a bond separable dipole moment function. The experimental part reports the results obtained on methane and silane by IR IR double resonance. The vibrational structure of the last unknown component (of F1 symmetry) of the 3ʋ3 level has been observed as well as those of the polyads (1100) (3000) and (2100) of silane. In the case of methane, the vibrational energy of the F1 level as well as the experimental values of the rotational and Coriolis constants is close to the calculated ones. For silane, the agreement is better both for the vibrational energies and for the rovibrational and rotational parameters. The stretch-bend Fermi resonances, not taken into account in this study, are weaker for silane than for methane, and are probably responsible for this.

An ongoing experiment at Fermilab intends to measure the ratio of the CP violation parameters epsilon-c'/epsilon-c to a precision of .001. The experimental technique and apparatus are described. Sources of systematic error are discussed and some preliminary data from the test run in 1985 is shown. The status of the analysis is described and plans for the upcoming final data run in March 1987 are given.