Marek Nowakowski

W- and Z-boson interactions in supersymmetric models with explicit R-parity violation

Abstract The minimal supersymmetric Standard Model with explicit R -parity non-conservation contains bilinear terms involving the left-handed lepton superfields and the Higgs chiral multiplet with hypercharge Y = +1, which cannot in general be rotated away in the presenceof soft-supersymmetry-breaking interactions. These bilinear lepton-number-violating terms are found to give rise to non-zero vacuum expectation values of the scalar neutrinos. This leads to non-universal and flavour-violating tree-level couplings of the W and Z bosons to charged leptons and neutrinos. The parameter space of this novel scenario is systematically analyzed and further restricted by a number of laboratory, astrophysical, and cosmological constraints. The possibility that our minimal model can account for the KARMEN anomaly is examined.

On gauge invariance of Breit-Wigner propagators

We present an approach to bosonic (Zo,W±) as well as fermionic (top-quark) Breit-Wigner propagators which is consistent with gauge invariance arguments. In particular, for theZo-boson propagator we extend previous analyses and show that the part proportional tokμkv/M2 must be modified near the resonance. We derive a mass shift which agrees with results obtained elsewhere by different methods. The modified form of a resonant heavy fermion propagator is also given.

Triplet Higgs bosons at e+e− colliders

Abstract We investigate the possibility of probing the triplet Higgs boson sector via single charged Higgs production in the process e+e− → H+lνl, at high energy electron-positron colliders, using the tree level H+W−Z coupling which is a unique feature of such models. We find that even LEP-200 can give nontrivial information up to M H ± ⋍ 120 GeV if the doublet -triplet mixing is not restricted by the current value of the ϱ parameter. Further we point out that in such models, the 4-body, tree level decay H + → W ∗ Z ∗ → 4 fermions dominates and hence provides a very clean signal. At NLC the discovery range for the charged Higgs in triplet models via this process is ∼ 400 GeV.

CP-ODD PHENOMENA DUE TO FINITE WIDTH EFFECTS OF THE TOP QUARK

Strong experimental indications exist that the top quark mass in the Standard Model (SM) exceeds the mass of the W gauge boson. Since this opens the decay mode t → Wb a suitable regularization of the top quark propagator in the s-channel is required in many tree reactions. As in the Z0 case this regularization essentially results in an. additional imaginary contribution (iΓtmt) to the propagator. This absorptive phase can combine with complex coupling constants of the charged current sector to give rise to new CP violating effects. Theoretical upper bounds for the size of these CP-odd signals are estimated in various extensions of the SM such as: the four generation SM, left-right symmetric models and models with two or three Higgs doublets.

The magnetic moments of baryons and the spin of the proton

Abstract Under reasonable assumptions we derive from the proton electromagnetic form factors those of the quark vector currents separately. Then we deduce the quark radii and magnetic moments in the proton and find a surprisingly large strangeness contribution. Using a constituent quark model, we relate the quark magnetic moments to the spin of the proton and confirm previous conclusions that it is not carried completely by quarks. If we extend the role of s-quarks in the proton to the SU(3)F octet then we predict the magnetic moments of the other baryons.

CP-violating scattering processes in the minimal supersymmetric standard model

Abstract We examine the possibility to find new CP violating signals in the supersymmetric extension of the standard model. We focus our investigation on high energy scattering processes suitable for the new generation of colliders. We point out that certain supersymmetric scenarios can account for quite large CP asymmetries due to the scalar quark-quark mixing.

Dominant three-body decays of a heavy higgs and top quark

AbstractWe calculate the dominant three body Higgs decays,H→W+W−(Z0, γ) and

The role of the axial anomaly in determining the quark spin fractions of the proton

H \to t\bar t(Z^0 ,\gamma ,g)