10,057 research outputs found
New examples of Calabi-Yau threefolds and genus zero surfaces
We classify the subgroups of the automorphism group of the product of 4
projective lines admitting an invariant anticanonical smooth divisor on which
the action is free. As a first application, we describe new examples of
Calabi-Yau 3-folds with small Hodge numbers. In particular, the Picard number
is 1 and the number of moduli is 5. Furthermore, the fundamental group is
non-trivial. We also construct a new family of minimal surfaces of general type
with geometric genus zero, K^2=3 and fundamental group of order 16. We show
that this family dominates an irreducible component of dimension 4 of the
moduli space of the surfaces of general type.Comment: 18 pages; v2: simplified some arguments in the last section, final
version to appear on Communications in Contemporary Mathematic
Qualidade e sustentabilidade.
O Conceito da qualidade. A história da qualidade. O sistema de gestão. Qualidade e meio ambiente. Atendimento ao cliente. Novos paradigmas de gestãobitstream/CNPAB-2010/27354/1/doc115.pd
Sign systems for touristic information: design and method
Sistemas de signos para informação turístic
Maxwell-Chern-Simons vortices in a CPT-odd Lorentz-violating Higgs Electrodynamics
We have studied BPS vortices in a CPT-odd and Lorentz-violating
Maxwell-Chern-Simons-Higgs (MCSH) electrodynamics attained from the dimensional
reduction of the Carroll-Field-Jackiw-Higgs model. The Lorentz-violating
parameter induces a pronounced behavior at origin (for the magnetic/electric
fields and energy density) which is absent in the MCSH vortices. For some
combination of the Lorentz-violating coefficients there always exist a
sufficiently large winding number such that for all
the magnetic field flips its signal, yielding two well defined regions with
opposite magnetic flux. However, the total magnetic flux remains quantized and
proportional to the winding number.Comment: Revtex style, 8 page
Control of quantum transverse correlations on a four-photon system
Control of spatial quantum correlations in bi-photons is one of the
fundamental principles of Quantum Imaging. Up to now, experiments have been
restricted to controlling the state of a single bi-photon, by using linear
optical elements. In this work we demonstrate experimental control of quantum
correlations in a four-photon state comprised of two pairs of photons. Our
scheme is based on a high-efficiency parametric downconversion source coupled
to a double slit by a variable linear optical setup, in order to obtain
spatially encoded qubits. Both entangled and separable pairs have been
obtained, by altering experimental parameters. We show how the correlations
influence both the interference and diffraction on the double slit.Comment: 14 pages, 6 figure
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