Indirect Measurement of the Vertex and Angles of the Unitarity Triangle

The precise measurements of the Bd oscillation frequency and the limit on the Bs one one as well as the determination of the Cabibbo-Kobayashi-Maskawa matrix element Vub improve the constraints on the other elements of this matrix. A fit to the experimental data and the theory calculations leads to the determination of the vertex of the unitarity triangle as: rho = 0.160 -0.070 +0.094 eta = 0.381 -0.058 +0.061. The values of its angles, in their customary definition in terms of sines for alpha and beta, are found to be: sin(2 alpha) = 0.06 -0.42 +0.35 sin(2 beta) = 0.75 +/- 0.09 gamma = 68 -12+11o. Indirect information on non-perturbative QCD parameters, on the presence of a CP violating complex phase in the CKM matrix and on the Bs oscillation frequency are also extracted.Comment: 12 pages, submitted to Physics Letters

ZZ Cross Section Measurements

Results on the cross section measurement of Z boson pair-production at LEP are presented. The more general case of neutral-current four-fermion production and the particular case of ZZ events enriched in b quarks are also discussed. All the results agree with the Standard Model predictions.Comment: To appear in the proceedings of ICHEP 2000, Osaka, Japan, July 27th-August 2nd, 200

Experimental Constraints on the Cabibbo-Kobayashi-Maskawa Matrix

The LEP investigation of the Bd and Bs oscillations and of the Cabibbo-Kobayashi-Maskawa matrix element Vub improve the constraints on the other elements of this matrix. From a fit to the experimental data and the theory calculations it is possible to determine the vertex of the unitarity triangle as: rho = 0.155 -0.105 +0.115 eta = 0.383 -0.060 +0.063. The corresponding values of its angles, in their customary definition in terms of sines for alpha and beta, are: sin(2 alpha) = 0.08 -0.50 +0.43 sin(2 beta) = 0.75 +/- 0.10 gamma = 68 +/- 15o. The fit also yields indirect information on the compatibility with zero of the CP violating phase of the matrix, on some non-perturbative QCD parameters and on the Bs oscillation frequency.Comment: 10 pages, to be published in the proceedings of the Workshop on CP Violation, Adelaide, Australia, July 3-8, 199

Recent Results from the L3 Experiment

A data sample corresponding to an integrated luminosity of 232pb^-1 was collected in 1997 and 1998 by the L3 experiment at LEP in e+e- collisions at centre-of-mass energies between 181.7GeV and 188.7GeV. Pair production of fermions and bosons is studied and compared with the Standard Model expectations. Events with a single detected photon or W boson are also considered. The measurement of several Standard Model cross sections is discussed. The presence and the magnitude of triple couplings of charged and neutral electroweak gauge bosons is investigated. These processes are used to probe New Physics beyond the Standard Model, including the existence of extra spatial dimensions.Comment: 17 Pages, 11 Figures, to appear in the proceedings of the XIV International Workshop on Quantum Field Theories and High Energy Physics, QFTHEP99, Moscow, Russia, 27 May - 2 June, 199

Measurement of the Running of the Electromagnetic Coupling at LEP

The study of low-angle and large-angle Bhabha scattering at LEP gives access to the running of the electromagnetic coupling. Two recent measurements of the OPAL and L3 collaborations probe the running of alpha in the regions 1.8GeV^2<-Q^2<6.1GeV^2 and 1800GeV^2 <-Q^2 <21600GeV^2, respectively. The strategies and the results of these studies are presented. A global overview is given of the agreement of these and previous L3 findings with the QED predictions.Comment: To appear in the Proceedings of the International Europhysics Conference on High Energy Physics, July 21st - 27th 2005, Lisboa, Portuga

Indirect Determination of the Vertex and Angles of the Unitarity Triangle

The values of the elements of the Cabibbo-Kobayashi-Maskawa matrix are constrained by direct and indirect measurements. A fit to experimental data and theory calculations allows the indirect determination of the vertex and angles of the unitarity triangle as: rho = 0.18 +/- 0.07 eta = 0.35 +/- 0.05 sin 2alpha = 0.14 +0.25 -0.38 sin 2beta = 0.73 +/- 0.07 gamma = 63 +8 -11 degrees. Information is derived on the presence of CP violation in the matrix, on non-perturbative QCD parameters and on the Bs oscillation frequency.Comment: Presented at the 5th International Symposium on Radiative Corrections (RADCOR-2000) Carmel CA, USA, 11-15 September, 200

Measurements of the Running of the Electromagnetic Coupling at LEP

The study of Bhabha scattering at e^+e^- colliders probes the running of the electromagnetic coupling. After early measurements by the VENUS collaboration at TRISTAN and the by L3 collaboration at LEP, two recent analyses have been performed by the OPAL and L3 collaborations. The OPAL collaboration studied high-statistics low-angle Bhabha scattering at LEP, achieving a precise determination of the running of alpha in the region 1.8GeV^2<-Q^2<6.1GeV^2. The L3 collaboration investigated high-energy large-angle Bhabha scattering to first probe the region 1800GeV^2 < -Q^2 < 21600GeV^2. All measurements are described and a global overview of their agreement with QED predictions is given.Comment: Invited talk at the XXVI Physics in Collisions Conference (PIC06), Buzios, Brasil, July 2006, 6 pages, LaTeX, 7 eps figures. PSN THUPL0

Study of Extra Space Dimensions in Vector Boson Pair Production at LEP

Recent theoretical scenarios propose that quantum gravity effects may manifest at LEP energies by means of gravitons that couple to Standard Model particles and propagate into extra space dimensions. These predictions are checked against the most recent experimental results on photon, W and Z pair production. No deviations from the Standard Model expectations are found and limits of the order of 1 TeV on the scale of these models are set.Comment: 6 pages, 1 figur

SCOAP3: where libraries, scientists and publishers meet repositories, peer-reviewed journals and Open Access

The inexorable growth of both Open Access and library budgetary concerns are calling for innovation in scholarly communication. The field of High-Energy Physics has decades of tradition in cross-border collaboration and Open Access and is now proposing an innovative model for scientific publishing: SCOAP3. This article presents a synopsis of this opportunity for libraries, scientists and publishers to invent a new future at the interface of Open Access, peer-reviewed journals and repositories

INSPIRE: A new information system for High-Energy Physics. Lessons learnt

E-Science brings opportunities and challenges for the world of scholarly communication: it amplifies the needs of scientists for fast, effective, unrestricted communication of ideas and scientific results, through Open Access; it enables automation of librarianship intelligence, providing new services to the scientific community for the discovery of information; it calls on libraries and information professionals to fill new roles, as evolving actors in the scholarly communication chain. The field of High-Energy Physics (HEP) has pioneered infrastructures for scholarly communication, with half a century of tradition in Open Access and pre-print dissemination and two decades of experiences in repositories. Scholarly communication in HEP is now moving fast in the e-Science era. This contribution will analyze the status of scholarly communication in the field and the potential offered by the inception of INSPIRE, the next-generation repository for the field