14 research outputs found
Role of beam polarization in the determination of and couplings from
We evaluate the constraints on anomalous trilinear gauge-boson couplings that
can be obtained from the study of electron-positron annihilation into pairs
at a facility with either the electron beam longitudinally polarized or both
electron and positron beams transversely polarized. The energy ranges
considered in the analysis are the ones relevant to the next-linear collider
and to LEP~200. We discuss the possibilities of a model independent analysis of
the general conserving anomalous effective Lagrangian, as well as its
restriction to some specific models with reduced number of independent
couplings. The combination of observables with initial and final state
polarizations allows to separately constrain the different couplings and to
improve the corresponding numerical bounds.Comment: 24 pages, LaTeX, 9 figures (available on request from the authors
Decoupling of Massive Right-handed Neutrinos
We investigate the effect of B+L - violating anomalous generation of massive
right-handed neutrinos on their decoupling, when the right-handed neutrino mass
is considerably greater than the right-handed gauge boson masses. Considering
normal annihilation channels, the Lee-Weinberg type of calculation, in this
case, gives an upper bound of about 700 Gev, which casts doubt on the existence
of such a right-handed neutrino mass greater than right-handed gauge boson
masses. We examine the possibility that a consideration of anomalous effects
related to the SU(2)_R gauge group may turn this into a lower bound of the
order of 100 Tev.Comment: 28 Pages, Latex, 2 figure
A Supersymmetric Theory of Flavor with Radiative Fermion Masses
Supersymmetric theories involving a spontaneously broken flavor symmetry can
lead to fermion masses which vanish at tree level but are generated by
radiative corrections. In the context of supersymmetric theories with minimal
low energy field content we discuss which fermion masses and mixings may be
obtained radiatively, and find that constraints from flavor changing
phenomenology imply that only the first generation fermion masses and some (but
not all) CKM mixings can naturally come from radiative corrections. We also
consider general conditions on theories of flavor which guarantee the existence
of tree level massless fermions while having non-trivial CKM matrix elements at
tree level. Two complete models of flavor are presented. In the first model,
all first generation fermion masses are radiatively generated. In the second
model, the electron and up quark mass are due to radiative corrections whereas
the down mass appears at tree level, as does a successful prediction for the
Cabibbo angle .Comment: 45 pages, LaTeX, 6 figure
Multiple lines of evidence for an Australasian geographic boundary in the Indo-Pacific humpback dolphin (Sousa chinensis): Population or species divergence?
The taxonomic status of humpback dolphins (genus Sousa, sub-family Delphininae) is unresolved. While the classification of this genus ranges from a single to three nominal species, the International Union for Conservation of Nature and the International Whaling Commission only recognise a 'two-species' taxonomy (S. teuszii in west Africa, and S. chinensis in the Indo-Pacific). Under the IUCN (2008), S. chinensis is listed as 'near threatened', but is only considered as a 'migratory' species in Australia. Taxonomic resolution of the genus Sousa is needed to define particular conservation status and develop appropriate management actions. Using phylogenetic analyses of 1,082 bp of mitochondrial and 1,916 bp of nuclear DNA, we provide multiple lines of genetic evidence for the genetic distinction of S. chinensis in China and Indonesia from S. chinensis in Australia. The separation of Australian Sousa from Sousa of Southeast Asia requires a review of their current conservation status and respective management actions