Theory and phenomenology of two-Higgs-doublet models

This article reports world averages of measurements of b-hadron, c-hadron, and tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through the end of 2011. In some cases results available in the early part of 2012 are included. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays and CKM matrix elements.

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Averages of b-hadron, c-hadron, and tau-lepton properties as of early 2012

https://bura.brunel.ac.uk/bitstream/2438/20604/1/FullText.pdf

Precision electroweak measurements on the Z resonance

We present a discussion of the precision for the PHOTOS Monte Carlo algorithm, with improved implementation of QED interference and multiple-photon radiation. The main application of PHOTOS is the generation of QED radiative corrections in decays of any resonances, simulated by a "host" Monte Carlo generator. By careful comparisons automated with the help of the MC-TESTER tool specially tailored for that purpose, we found that the precision of the current version of PHOTOS is of 0.1% in the case of Z and W decays. In the general case, the precision of PHOTOS was also improved, but this will not be quantified here.

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PHOTOS Monte Carlo: A Precision tool for QED corrections in $Z$ and $W$ decays

Glueballs, Hybrids, Multiquarks. Experimental facts versus QCD inspired concepts

Infrared and collinear safe event shape distributions and their mean values are determined in e(+)e(-) collisions at centre-of-mass energies between 45 and 202GeV. A phenomenological analysis based on power correction models including hadron mass effects for both differential distributions and mean values is presented. Using power corrections, alpha(s) is extracted from the mean values and shapes. In an alternative approach, renormalisation group invariance (RGI) is used as an explicit constraint, leading to a consistent description of mean values without the need for sizeable power corrections. The QCD beta-function is precisely measured using this approach. From the DELPHI data on Thrust, including data from low energy experiments, one finds beta(0) = 7.86 +/- 0.32 for the one loop coefficient of the beta-function or, assuming QCD, n(f) = 4.75 +/- 0.44 for the number of active flavours. These values agree well with the QCD expectation of beta(0) = 7.67 and n(f) 5. A direct measurement of the full logarithmic energy slope excludes light gluinos with a mass below 5GeV.

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A study of the energy evolution of event shape distributions and their means with the DELPHI detector at LEP

A search for pair-produced charged Higgs bosons was performed in the data col- lected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 209 GeV. Five different final states, τ + ντ τ − ¯τ ,cscs, csτ − ¯ ντ ,W ∗ AW ∗ Aa nd W ∗ Aτ − ¯τ were considered, accounting for the major expected decays in type I and type II Two Higgs Doublet Models. No significant excess of data compared to the expected Standard Model processes was observed. The existence of a charged Higgs boson with mass lower than 76.7 GeV/c 2 (type I) or 74.4 GeV/c 2 (type II) is ex- cluded at the 95% confidence level, for a wide range of the model parameters. Model independent cross-section limits have also been calculated.

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Search for charged Higgs bosons at LEP in general two Higgs doublet models

W(+)W(-)gamma production at LEP2 is studied using data collected with the DELPHI detector at centre-of-mass energies between 189 GeV and 209 GeV, corresponding to an integrated luminosity of about 600 pb(-1). Cross-sections are measured for the production of W+W- with a hard, central and isolated photon in the final state, and are found to be compatible with the Standard Model prediction. The photon energy spectra are used to derive limits on anomalous contributions to the W(+)W(-)Z(o)gamma and W(+)W(-)gammagamma vertices.

Measurement of the e+ e- ---> W+ W- gamma cross-section and limits on anomalous quartic gauge couplings with DELPHI

Searches for pair-production of supersymmetric particles under the assumption of non-conservation of R-parity with a dominant LL (E) over bar or (U) over bar(D) over bar(D) over bar term have been performed using the data collected by the DELPHI experiment at LEP in e(+)e(-) collisions at centre-of-mass energies from 192 up to 208 GeV. No excess of data above Standard Model expectations was observed. The results were used to constrain the MSSM parameter space and to derive limits on the masses of supersymmetric particles.

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Search for supersymmetric particles assuming R-parity non-conservation in e(+)e(-) collisions at root s=192 to 208 GeV

Hadronic event shape distributions are determined from data in e(+)e(-) collisions between 183 and 207 GeV. From these the strong coupling alpha(s) is extracted in O(alpha(s)(2)), NLLA and matched O(alpha(s)(2))+ NLLA theory. Hadronisation corrections evaluated with fragmentation model generators as well as an analytical power ansatz are applied. Comparing these measurements to those obtained at and around M-Z allows a combined measurement of alpha(s) from all DELPHI data and a test of the energy dependence of the strong coupling.

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H.M. Blom

Papers

A study of the energy evolution of event shape distributions and their means with the DELPHI detector at LEP

Search for charged Higgs bosons at LEP in general two Higgs doublet models

Measurement of the e+ e- ---> W+ W- gamma cross-section and limits on anomalous quartic gauge couplings with DELPHI

Search for supersymmetric particles assuming R-parity non-conservation in e(+)e(-) collisions at root s=192 to 208 GeV

The measurement of Alpha s from event shapes with the DELPHI detector at the highest LEP energies