In this paper we describe Herwig++ version 2.3, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects. Comment: 153 pages, program and additional information available from http://projects.hepforge.org/herwig . Updated description to Herwig++ version 2.3 and added one author

/pdf/herwig-physics-and-manual-4sr09wbmek.pdf

Herwig++ Physics and Manual

In this paper we describe Herwig++ version 2.3, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects.

/pdf/herwig-physics-and-manual-2ysstfwnlz.pdf

The anatomy of electroweak symmetry breaking: Tome I: The Higgs boson in the Standard Model

The salient features of CP-violating interactions in the standard electroweak theory and in a few of its popular extensions are discussed. Moreover a brief overview is given on the status and prospects of searches for CP non-conservation effects in low and high energy experiments.

CP violation

http://cds.cern.ch/record/246578/files/th-6793-93.pdf

The τ decay library TAUOLA, version 2.4

Structure functions in tau decays

Toponium production at future hadron colliders is investigated. Perturbative QCD corrections to the production cross section for gluon fusion are calculated as well as the contributions from gluon-quark and quark-antiquark collisions to the total cross section. The dependence on the renormalization and factorization scales and on the choice of the parton distribution functions is explored. QCD corrections to the branching ratio of ηt into γγ are included and the two-loop QCD potential is used to predict the wave function at the origin. The branching ratio of ηt into γZ, ZZ, HZ and W W is compared with the γγ channel.

QCD corrections to toponium production at hadron colliders

In this paper we compute the branching ratios of the tau decays into three mesons. The hadronic matrix elements are obtained by first using the structure of the chiral currents and that of the Wess-Zumino anomaly and finally implementing all possible low-lying resonances in the different channels.

Tau decays into three pseudoscalar mesons

We discuss the idea that the nontrivial vacuum structure in QCD may induce transverse momentum and spin correlations of the initial state partons in Drell-Yan type reactions, i.e. in hadron-hadron collisions with production of a vector bosonV=γ*,Z,W±. Transverse momentum correlations are found to have practically no effect on observable quantities, but spin correlations have drastic consequences for the polarization density matrices of theV-bosons. We therefore propose measurements of theV polarization as a good test for the basic factorization hypothesis which, so far, has been assumed to be valid in numerous applications of the naive and QCD-improved parton model. We compare our ansatz for a spin correlation violating factorization with data from the NA 10 collaboration onγ* production inπ−N scattering. We find that the data give an indication of spin correlations of the partons in the initial state to be present.

E. Mirkes

Papers

Structure functions in tau decays

QCD corrections to toponium production at hadron colliders

Tau decays into three pseudoscalar mesons

Spin effects and factorization in the Drell-Yan process

CP violation in semileptonic τ decays with unpolarized beams