2,607 research outputs found
Biologia e controle de nematóide de cisto da soja (Heterodera glycines Ichinohe) (06.04.02.333.01).
Beam test of a superconducting cavity for the Fermilab high-brightness electron photo-injector
Self-consistent Approach to Off-Shell Transport
The properties of two forms of the gradient expanded Kadanoff--Baym
equations, i.e. the Kadanoff--Baym and Botermans-Malfliet forms, suitable to
describe the transport dynamics of particles and resonances with broad spectral
widths, are discussed in context of conservation laws, the definition of a
kinetic entropy and the possibility of numerical realization. Recent results on
exact conservations of charge and energy-momentum within Kadanoff-Baym form of
quantum kinetics based on local coupling schemes are extended to two cases
relevant in many applications. These concern the interaction via a finite range
potential, and, relevant in nuclear and hadron physics, e.g. for the
pion--nucleon interaction, the case of derivative coupling.Comment: 35 pages, submitted to issue of Phys. Atom. Nucl. dedicated to S.T.
Belyaev on the occasion of his 80th birthday. Few references are adde
Implicit Regularization and Renormalization of QCD
We apply the Implicit Regularization Technique (IR) in a non-abelian gauge
theory. We show that IR preserves gauge symmetry as encoded in relations
between the renormalizations constants required by the Slavnov-Taylor
identities at the one loop level of QCD. Moreover, we show that the technique
handles divergencies in massive and massless QFT on equal footing.Comment: (11 pages, 2 figures
Inhomogeneous cosmologies, the Copernican principle and the cosmic microwave background: More on the EGS theorem
We discuss inhomogeneous cosmological models which satisfy the Copernican
principle. We construct some inhomogeneous cosmological models starting from
the ansatz that the all the observers in the models view an isotropic cosmic
microwave background. We discuss multi-fluid models, and illustrate how more
general inhomogeneous models may be derived, both in General Relativity and in
scalar-tensor theories of gravity. Thus we illustrate that the cosmological
principle, the assumption that the Universe we live in is spatially
homogeneous, does not necessarily follow from the Copernican principle and the
high isotropy of the cosmic microwave background.Comment: 17 pages; to appear in GR
Nonanalytic behavior of the spin susceptibility in clean Fermi systems
The wavevector and temperature dependent static spin susceptibility,
\chi_s(Q,T), of clean interacting Fermi systems is considered in dimensions
1\leq d \leq 3. We show that at zero temperature \chi_s is a nonanalytic
function of |Q|, with the leading nonanalyticity being |Q|^{d-1} for 1<d<3, and
Q^2\ln|Q| for d=3. For the homogeneous spin susceptibility we find a
nonanalytic temperature dependence T^{d-1} for 1<d<3. We give qualitative
mode-mode coupling arguments to that effect, and corroborate these arguments by
a perturbative calculation to second order in the electron-electron interaction
amplitude. The implications of this, in particular for itinerant
ferromagnetism, are discussed. We also point out the relation between our
findings and established perturbative results for 1-d systems, as well as for
the temperature dependence of \chi_s(Q=0) in d=3.Comment: 12pp., REVTeX, 5 eps figures, final version as publishe
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