PHENOMENOLOGY OF STRONG AND ELECTROWEAK INTERACTIONS AT COLLIDERS

Strong and electroweak phenomenology at present and future high energy colliders will be analyzed with the methods of field theory.
The research activity is concentrated on a few general topics:
- Advanced techniques for multi-loop and one loop multi-leg calculations and their numerical implementation
- Phenomenology of Higgs, multi jets and heavy bosons at LHC and LC
- Monte Carlos for multi-body final states at LHC and their use for realistic simulations
- Threshold resummations and power corrections in perturbative QCD with applications to collider processes.
- Study of inclusive semileptonic and radiative B decays in the Standard Model and beyond.
- Phenomenology of supersymmetric models.
- EW precision tests and physics beyond the SM
- Analysis of the theoretical uncertainties in the determination of parton distributions.
- Multi-leg 1-loop production in QCD and Higgs production using unitarity and twistor-inspired techniques.

Some of the main results along these lines, obtained recently by the members of the collaboration, can be summarized as follows:
* A comprehensive study of two-loop Feynman diagrams with three external legs has been performed. Due to the exchange of massless gauge-bosons, these give raise to infrared and collinear divergencies. A classification of infrared singular configurations, based on solutions of Landau equations, has been introduced. Numerical results for all different families of multi-scale, two-loop, three-point infrared divergent diagrams have been performed.
* The result for the Higgs-dependent electroweak two-loop bosonic contributions to the effective leptonic mixing angle of the $Z$-boson in the Standard Model has been presented.
* The four-loop QCD corrections to the electroweak rho-parameter arising from top and bottom quark loops have been computed. The predictions for the shift of the weak mixing angle and the W-boson mass is thus stabilized.
* By studying charge asymmetries at the NLO in l+ l- plus 1 jet production processes at the LHC, the possibility of performing precision measurements of the Weinberg mixing angle has been investigated.
* A code (ALPGEN) for simulating high energy multi-particle production processes at Tevatron and LHC has been continuously updated and maintained, both adding new hard processes and introducing a better matching between Parton Shower and Matrix Element contributions.
* Sudakov resummation techniques have been extended to include a new class of nonlogarithmic terms, and have been employed to study power corrections for event shapes in e+ e- annihilation, in particular the C-parameter and the class of angularities.
* The application of string derived techniques to perturbative QCD has been studied: a complete understanding of the rules to compute one-loop,off-shell gluon correlation functions, as well as two--loop, off-shell scalar correlations has been achieved.The formalism has also been applied to two-loop effective actions.
* Computation of the 7-gluon 1-loop amplitude in the N=4 SUSY sector of QCD using unitarity and twistor-inspired techniques
* A general subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD has been laid out.
* The MonteCarlo and event generator PHASE has been released. It is dedicated to six fermion physics at LHC in 4qlnu channels.
* The first version of PHANTOM, a complete six fermion MonteCarlo for LHC, has been used for studies of Boson fusion and Higgs production.
* The influence of the 1-loop electroweak corrections on the production of two vector bosons at the LHC has been analysized.
* Exhaustive study of higher order perturbative corrections to inclusive semileptonic B decays has beem completed. It has been implemented the theoretical calculation of the moments of b->clnu and b->ulnu distributions for the experimental collaborations, as well as a model independent study of b->s gamma and b->s l+l- decays to put constraints on the Wilson coefficients.
* Precise calculation of the gluino width in the split supersymmetry framework has been performed

In the coming years, the activity of TO23 will continue the above program of research, and in particular it will be dedicated to:
- Multi loop massive diagrams evaluation, extending the results of TOPSIDE
- Two loops Standard Model renormalization
- New methods for computing multi-particle one loop corrections will be applied to computing relevant processes at e+ e- and hadronic colliders.
- Multi-leg 1-loop production in the N=4 SUSY sector of QCD.
- General algorithms to compute production rates of collision processes at NNLO accuracy in QCD.
- Study of resummations and models of power-suppressed corrections to QCD cross-sections. Specifically: a further extension of threshold resummation for the Drell-Yan process to contributions suppressed by a power of the Mellin variable N will be attempted.Dispersive methods to study power corrections will be applied to processes of interest at hadron colliders, for example inclusive jet cross sections.
- Possibility of applying string derived techniques to the computationof two-loop gluon amplitudes and Yang-Mills effective actions.
- Calculation of higher order effects and refinement of previous work on semileptonic inclusive B decays in order to reduce the theoretical error in Vcb and Vub determination.
- Event generator for b->u l nu decays, QED corrections to inclusive semileptonic B decays, NNLO matrix elements for b->s gamma, power suppressed perturbative corrections to B->Xc l nu
- Higgs + 3 jet production, via gluon fusion e via weak-boson fusion (WBF),to test the effectiveness of the central jet veto in WBF.
- Higgsstrahlung in Drell-Yan production at LHC, using MC@NLO, a MonteCarlo generator interfaced with full 1-loop calculations;
- Application of the general subtraction scheme for computing NNLO corrections envisaged above to specific production processes
- Higgs production using matrix-element Monte Carlo generators
- Hard processes in hadron collision. The Monte Carlo ALPGEN for realistic multiparticle studies at TEVATRON and LHC will be further developed.
- Techniques to compute one-loop amplitudes automatically and recursively will be analyzed and improved.
- Boson Boson scattering at LHC: possibility to evaluate effects of electroweak symmetry breaking and possible signal of new physics in WW fusion processes.
- The Monte Carlo PHANTOM for complete six fermion similation will be released.It will
be used for phemomenological studies including detector simulation an it will be extended to study non standard EWSB scenarios.
- The neural networks approach has been used to fit the parton distribution functions in order to faithfully estimate their uncertainty at present and future colliders.