A. Freitas

Slepton production at e + e- and e-e- linear colliders

Abstract.High-precision analyses are presented for the production of scalar sleptons, selectrons and smuons in supersymmetric theories, at future e + e- and e-e- linear colliders. Threshold production can be exploited for measurements of the selectron and smuon masses, an essential ingredient for the reconstruction of the fundamental supersymmetric theory at high scales. The production of selectrons in the continuum will allow us to determine the Yukawa couplings in the selectron sector, scrutinizing the identity of the Yukawa and gauge couplings, which is a basic consequence of supersymmetry. The theoretical predictions are elaborated at the one-loop level in the continuum, while at threshold non-zero width effects and Sommerfeld rescattering corrections are included. The phenomenological analyses are performed for e + e- and e-e- linear colliders with energy up to about 1 TeV and with high integrated luminosity up to 1 ab-1 to cover the individual slepton channels separately with high precision.

Determining sneutrino masses and physical implications

In some areas of supersymmetry parameter space, sneutrinos are lighter than the charginos and the next-to-lightest neutralino, and they decay into the invisible neutrino plus lightest-neutralino channel with probability one. In such a scenario they can be searched for in decays of charginos that are pair produced in

Two-loop Fermionic Electroweak Corrections to the Effective Leptonic Weak Mixing Angle in the Standard Model

{e}^{+}{e}^{\ensuremath{-}}

Sneutrino production at e + e- linear colliders: addendum to slepton production

collisions, and in associated sneutrino-chargino production in photon-electron collisions. The sneutrino properties can be determined with high accuracy from the edges of the decay energy spectra in the first case and from threshold scans in the second. In the final part of the report we investigate the mass difference of sneutrinos and charged sleptons between the third and the first two generations in seesaw-type models of the neutrino/sneutrino sector. For a wide range these mass differences are sensitive to the seesaw scale.

Corrections to quark asymmetries at LEP

We give some details of the recently completed calculation of the full two-loop fermionic corrections to the effective leptonic weak mixing angle, sin 2 θ eff lept . Among others, we describe the C++ library DiaGen/IdSolver, which was used to reduce the two-loop light fermion vertex diagrams to linear combinations of master integrals with rational function coefficients.

SUSY parameter analysis at TeV and Planck scales

Abstract.Complementing the preceding study of charged scalar leptons, the sector of the neutral scalar leptons, sneutrinos, is investigated in a high-precision analysis for future e + e- linear colliders. The theoretical predictions for the cross-sections are calculated at the thresholds for non-zero widths and in the continuum including higher-order corrections at the one-loop level. Methods for measuring the sneutrino masses and the electron-sneutrino-gaugino Yukawa couplings are presented, addressing theoretical problems specific for the sneutrino channels.

Two loop results for M(W) in the standard model and the MSSM

Abstract.The most precise measurement of the weak mixing angle

Towards Better Constraints on the Higgs Boson Mass: Two-Loop Fermionic Corrections to sin^2(theta_eff)

\sin^2 \theta_{\mathrm{eff}}^l

Precise predictions for slepton pair production

at LEP is from the forward-backward asymmetry

Two-loop results for MW in the standard model and the MSSM

e^ + e^- \rightarrow b \overline{b}