The 2009 Europhysics Conference on High Energy Physics

We present the most precise single measurement of the W boson mass and and a measurement of the W width using data collected with the D0 experiment. An integrated luminosity of 1 fb-1 yields 499,830 W->evcandidates. The mass is measured with an uncertainty of less than 45 MeV while the width uncertainty is less than 75 MeV.

A precise measurement of the mass of the W boson will be essential to provide improved indirect constraints, e.g. on the Higgs boson mass. Using new methods developed for this challenging measurement, the performance expected is presented, evaluating various sources of systematic uncertainties, both of experimental and theoretical nature. The focus of this contribution will be on the...

The claim that the W mass will be measured at the LHC with a precision of O(10) MeV is critically reviewed. It is argued that such a precision cannot be achieved, unless a dedicated measurement programme, specific to the LHC collider is pursued. We propose such a programme. Its main target is to significantly improve the experimental control of the relative polarization of the W+, W- and...

We present three analyses of the mass of the top quark (mt) using top-antitop candidate events collected by the DO experiment during the current run of the Fermilab Tevatron Collider: (i) a 3.6 events/fb sample of data in the lepton+jets channel analyzed to extract a precision value of mt using the “Matrix-Element” method (ME), wherein each event probability is calculated from the differential...

We report the results of the measurements of the top quark mass using top pair events corresponding to an integrated luminosity of more than 4 fb-1 from proton-antiproton collisions at the Tevatron, recorded by the CDF II detector. We present different results using various techniques in the lepton+jets, dilepton, and all-jets channels, and describe the current status of the systematic...

Results from the global Standard Model (SM) fit to electroweak precision data, including newest Tevatron measurements, are reviewed and discussed. The constraint on the Higgs boson mass obtained from the fit is convolved with the high-scale behaviour of the Higgs quartic coupling to derive likelihoods for stability, metastability or instability scenarios of the SM. Information from the...

In this talk, we report on a recent next-to-leading order QCD calculation of the production of a W boson in association with three jets at hadron colliders. The computation is performed by combining two programs, BlackHat for the computation of the virtual one-loop matrix elements and Sherpa for the real emission part.

We report on recent progress on NLO QCD calculations using the OPP method. The method gives a complete description of the one-loop matrix element. We will also discuss the development of the programmes, HELAC-1L and HELAC-DIPOLES that allow for a fully numerical evaluation of NLO QCD corrections.

Measurements of the production of events containing isolated high energy leptons (electrons, muons or taus) and missing transverse momentum produced in ep collisions have been performed with the H1 and ZEUS detectors at HERA in the period 1994-2007. In addition, topologies with more than one high energy isolated lepton (electron or muon) are analyzed. The data samples corresponds to an...

Measurements of Neutral Current (NC) ep -> e X and Charged Current (CC) ep -> nu X cross sections by the H1 and ZEUS collaborations are presented using HERA data recorded during the years 1994-2007. The cross sections are measured in the region of large negative four-momentum transfer squared Q2 >200 GeV^2. Single differential and double-differential cross-sections are extracted and and...

An update of the theoretical prediction for the muon anomalous magnetic moment within the Standard Model is presented. It is based on recent low energy e+e- data for the leading order hadronic contributions as well as developments in the estimates of the hadronic light-by-light term. The theoretical prediction is confronted to the world average value of the experimentally measured...

The KLOE experiment, operating at the Frascati phi-factory DAPHNE, has measured the differential cross section for the process e+ e- --> pi+ pi- gamma as a function of the pi+pi- invariant mass, M(pipi). From the measured differential $M(pipi) spectrum inclusive of final state radiation, the total sigma(pi+pi-(gamma)) cross section is determined using the QED radiator function. The...

We revisit the procedure for comparing the pi pi spectral function measured in tau decays to that obtained in e+e- annihilation. We re-examine the isospin-breaking corrections using new experimental and theoretical input, and find improved agreement between the tau- --> pi- pi0 nu_tau branching fraction measurement and its prediction using the isospin-breaking-corrected e+e- --> pi+pi-...

We report a study of $\tau^- \to \pi^- \pi^+ \pi^- \nu$, $\tau^- \to K^- \pi^+ \pi^- \nu$, $\tau^- \to K^- K^+ \pi^- \nu$ and $\tau^- \to K^- K^+ K^- \nu$ decays using a 666 fb$^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We present the branching fractions as well as the unfolded mass spectra of the total hadronic system for these four...

A selection of electroweak measurements performed by the BaBar experiment operating at the Stanford Linear Accelerator Center is presented. Using a sample of 122 million Y(3S) decays, we measure the ratio R = BR(Y(1S) -> tautau)/BR(Y(1S) -> mumu); the measurement is intended as a test of the lepton universality and as a search for a light pseudoscalar Higgs boson in NMSSM scenarios....

The cryoEDM experiment at the Institut Laue-Langevin in Grenoble will measure the electric dipole moment (EDM) of the neutron with unparalleled precision. A neutron EDM arises due to CP violation. The cryoEDM experiment is sensitive to levels of CP violation predicted by many "beyond the standard model" theories and the result will therefore constrain or support these theories. The current...