388 research outputs found
Neutrino mixing, interval matrices and singular values
We study the properties of singular values of mixing matrices embedded within
an experimentally determined interval matrix. We argue that any physically
admissible mixing matrix needs to have the property of being a contraction.
This condition constrains the interval matrix, by imposing correlations on its
elements and leaving behind only physical mixings that may unveil signs of new
physics in terms of extra neutrino species. We propose a description of the
admissible three-dimensional mixing space as a convex hull over experimentally
determined unitary mixing matrices parametrized by Euler angles which allows us
to select either unitary or nonunitary mixing matrices. The unitarity-breaking
cases are found through singular values and we construct unitary extensions
yielding a complete theory of minimal dimensionality larger than three through
the theory of unitary matrix dilations. We discuss further applications to the
quark sector.Comment: Misprints correcte
Single chargino production with R-parity lepton number violation in electron-electron and muon-muon collisions
We examine single chargino production in conjunction with R-parity lepton
number violation in future lepton-lepton collisions. Present bounds on R-parity
violating couplings allow for a production cross section of the order of
for a wide range of sneutrino and chargino masses.
Scenarios of chargino decay which lead to purely leptonic signals in the final
state and without missing energy are also discussed.Comment: Unfortunate mistake in the list of authors corrected, 10 pages, 4
figure
Quantization and renormalization of the manifest left-right symmetric model of electroweak interactions
Quantization and renormalization of the left-right symmetric model is the
main purpose of the paper. First the model at tree level with a Higgs sector
containing one bidoublet and two triplets is precisely discussed. Then the
canonical quantization and Faddeev-Popov Lagrangian are carried out ('t Hooft
gauge). The BRST symmetry is discussed. Subsequently the on mass shell
renormalization is performed and, as a test of consistency, the renormalization
of the ZNiNj vertex is analyzed.Comment: 74 pages, 65 Postscript figures, submitted to Annals of Physic
On the massive two-loop corrections to Bhabha scattering
We overview the general status of higher order corrections to Bhabha
scattering and review recent progress in the determination of the two-loop
virtual corrections. Quite recently, they were derived from combining a
massless calculation and contributions with electron sub-loops. For a massive
calculation, the self-energy and vertex master integrals are known, while most
of the two-loop boxes are not. We demonstrate with an example that a study of
systems of differential equations, combined with Mellin-Barnes representations
for single masters, might open a way for their systematic calculation.Comment: 8 pages, 2 figures, latex, Contribution to Proceedings of XXIX Conf.
of Theoretical Physics: Matter to the Deepest, Ustron, Poland, 8-14 September
2005; preprint number adde
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