40,157 research outputs found
Sharp de Rham realization
We introduce the "sharp" (universal) extension of a 1-motive (with additive
factors and torsion) over a field of characteristic zero. We define the "sharp
de Rham realization" by passing to the Lie-algebra. Over the complex numbers we
then show a (sharp de Rham) comparison theorem in the category of formal Hodge
structures. For a free 1-motive along with its Cartier dual we get a canonical
connection on their sharp extensions yielding a perfect pairing on sharp
realizations. We thus provide "one-dimensional sharp de Rham cohomology" of
algebraic varieties.Comment: 30 page
On the Deligne--Beilinson cohomology sheaves
We are showing that the Deligne--Beilinson cohomology sheaves are torsion free by assuming Kato's conjectures
hold true for function fields. This result is `effective' for ; in this
case, by dealing with `arithmetic properties' of the presheaves of mixed Hodge
structures defined by singular cohomology, we are able to give a cohomological
characterization of the Albanese kernel for surfaces with .Comment: 12 pages, LaTeX 2.0
The Higgs mass as a function of the compactification scale
We calculate to a few percent precision the Higgs potential in a model with
supersymmetry broken by boundary conditions on an extra-dimension, compactified
to a segment of length , and a top quark quasi-localized on one of the two
boundaries. 1/L alone, in the range 2-4 TeV, determines the Higgs mass, in the
range 110-125 GeV, and the spectrum of gauginos, higgsinos and of the
third-generation squarks. Lower values of 1/L cannot be excluded, with a
progressive delocalization of the top quark.Comment: 22 pages, 6 figure
Expectations for LHC from Naturalness: Modified vs. SM Higgs Sector
Common lore has it that naturalness of electroweak breaking in the SM
requires new physics (NP) at Lambda < 2-3 TeV, hopefully within the reach of
LHC. Moreover the Higgs should be light (m_h < 219 GeV) to pass electroweak
precision tests (EWPT). However one should be prepared for "unexpected"
(although admittedly unpleasant) results at LHC, i.e. no NP and/or a heavy
Higgs. We revisit recent attempts to accommodate this by modifying the SM Higgs
sector (using 2-Higgs-doublet models). We find that these models do not improve
the naturalness of the SM, and so they do not change the expectations of
observing NP at LHC. We also stress that a heavy SM Higgs would not be evidence
in favour of a modified Higgs sector, provided certain higher order operators
influence EWPT. On the other hand, we show that NP can escape LHC detection
without a naturalness price, and with the pure SM as the effective theory valid
at LHC energies, simply if the cut-off for top loops is slightly lower than for
Higgs loops.Comment: 37 pages, LaTeX, 13 figure
Study of the 16O(p,gamma) Reaction at Astrophysical Energies
The Feshbach theory of the optical potential naturally leads to a microscopic
description of scattering in terms of the many-body self-energy. We consider a
recent calculation of this quantity for 16O and study the possibility of
applying it at astrophysical energies. The results obtained for the phase
shifts and the 16O(p,\gamma) capture suggest that such studies are feasible but
the calculations require some improvement geared to this specific task.Comment: 4 pages, 3 figures; Proceedings of Nuclei In The Cosmos VIII, to
appear in Nucl. Phys.
Toward an Ab-initio Description of Quasiparticle Properties
Preliminary ab-initio applications of many-body Green's functions theory to
the ground state of He-4 suggest that high accuracy can be achieved in the
so-called Faddeev-random-phase-approximation method.
We stress the potentialities of this approach for microscopic studies of
medium-large nuclei and report applications to 1s0d and 1p0f-shell nuclei. In
particular, we discuss the role of long-range correlations on spectroscopic
factors and their dependence on asymmetry.Comment: Minor corrections and references added -- Proceedings of the Varenna
conference, June 15-19, 200
Electroweak Corrections
The test of the electroweak corrections has played a major role in providing
evidence for the gauge and the Higgs sectors of the Standard Model. At the same
time the consideration of the electroweak corrections has given significant
indirect information on the masses of the top and the Higgs boson before their
discoveries and important orientation/constraints on the searches for new
physics, still highly valuable in the present situation.The progression of
these contributions is reviewed.Comment: 14 pages, 3 figures, a contribution to "The Standard Theory up to the
Higgs discovery - 60 years of CERN
Isotopes in hydrology and hydrogeology
The structure, status, and processes of the groundwater system, which can only be acquired through scientific research efforts, are critical aspects of water resource management. Isotope hydrology and hydrogeology is a genuinely interdisciplinary science. It developed from the application of methods evolved in physics (analytical techniques) to problems of Earth and the environmental sciences since around the 1950s. In this regard, starting from hydrogeochemical data, stable and radioactive isotope data provide essential tools in support of water resource management. The inventory of stable isotopes, which has significant implications for water resources management, has grown in recent years. Methodologies based on the use of isotopes in a full spectrum of hydrological problems encountered in water resource assessment, development, and management activities are already scientifically established and are an integral part of many water resource investigations and environmental studies. The driving force behind this Special Issue was the need to point the hydrological and water resource management societies in the direction of up-to-date research and best practices
Geometry and dimensionality reduction of feature spaces in primary visual cortex
Some geometric properties of the wavelet analysis performed by visual neurons
are discussed and compared with experimental data. In particular, several
relationships between the cortical morphologies and the parametric dependencies
of extracted features are formalized and considered from a harmonic analysis
point of view
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