W. Majerotto

The role of polarized positrons and electrons in revealing fundamental interactions at the Linear Collider

The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.

Improved supersymmetric QCD corrections to Higgs boson decays into quarks and squarks

We improve the calculation of the supersymmetric

Production and decay of neutralinos in e+e− annihilation

O(alpha_s)

Effect of supersymmetric phases on lepton dipole moments and rare lepton decays

QCD corrections to the decays of Higgs bosons into quarks and squarks in the Minimal Supersymmetric Standard Model. In the on-shell renormalization scheme these corrections can be very large, which makes the perturbative expansion unreliable. This is especially serious for decays into bottom quarks and squarks for large

CP asymmetries in neutralino production in e + e − -collisions

tanbeta

One-loop corrections to the chargino and neutralino mass matrices in the on-shell scheme

. Their corrected widths can even become negative. We show that this problem can be solved by a careful choice of the tree-level Higgs boson couplings to quarks and squarks, in terms of the QCD and SUSY QCD running quark masses, running trilinear couplings

SUSY-QCD corrections to scalar quark decays into charginos and neutralinos

A_q

Squark and gluino decays for large tan β

, and on-shell left-right mixing angles of squarks. We also present numerical results for the corrected partial decay widths for the large

CP violation in charged Higgs boson decays in the MSSM with complex parameters

tanbeta

Test of lepton flavour violation at the LHC

case.