80 research outputs found
A hermitian analogue of the Broecker-Prestel theorem
The Broecker-Prestel local-global principle characterizes weak isotropy of
quadratic forms over a formally real field in terms of weak isotropy over the
henselizations and isotropy over the real closures of that field. A hermitian
analogue of this principle is presented for algebras of index at most two. An
improved result is also presented for algebras with a decomposable involution,
algebras of pythagorean index at most two, and algebras over SAP and ED fields.Comment: Final pre-publication versio
Hermitian Sylvester and Pfister theorems for Azumaya algebras with involution
We investigate connections between a pairing of hermitian forms extensively
studied by Garrel, signatures of hermitian forms, and positive semidefinite
quadratic forms, and use them to prove a version of Sylvester's law of inertia
as well as Pfister's local-global principle for hermitian forms over Azumaya
algebras with involution over semilocal rings.Comment: 29 page
Signatures of hermitian forms and the Knebusch Trace Formula
Signatures of quadratic forms have been generalized to hermitian forms over
algebras with involution. In the literature this is done via Morita theory,
which causes sign ambiguities in certain cases. In this paper, a hermitian
version of the Knebusch Trace Formula is established and used as a main tool to
resolve these ambiguities.
The last page is an erratum for the published version. We inadvertently (I)
gave an incorrect definition of adjoint involutions; (II) omitted dealing with
the case . As , the
omission does not affect our reasoning or our results. For the sake of
completeness we point out where some small changes should be made in the
published version.Comment: This is the final version before publication. The last page is an
updated erratum for the published versio
CFHTLS weak-lensing constraints on the neutrino masses
We use measurements of cosmic shear from CFHTLS, combined with WMAP-5 cosmic
microwave background anisotropy data, baryonic acoustic oscillations from SDSS
and 2dFGRS and supernovae data from SNLS and Gold-set, to constrain the
neutrino mass. We obtain a 95% confidence level upper limit of 0.54 eV for the
sum of the neutrino masses, and a lower limit of 0.03 eV. The preference for
massive neutrinos vanishes when shear-measurement systematics are included in
the analysis.Comment: 10 pages. Published versio
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