40,697 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.
The importance of Enrichment Factor (EF) and Geoaccumulation Index (Igeo) to evaluate the soil contamination
Heavy metals are natural constituents of soils and their concentration varies depending on parental materials. In the last years, the content of heavy metal in soils has increased due to human activities as: distribution of fertilizers, pesticides, industries, waste disposal and air pollution. Due to these activities the life capacity of soils decreased; especially where the natural background is already high because of natural parental material richness in heavy metal. As a matter of fact it is very important to distinguish between the natural background values and anthropogenic inputs, and to understand that the background values change from area to area and with the scale of the area investigated. There is currently a wide variety of methods used to evaluate soil contamination. To evaluate the soil contamination rate different indexes like Enrichment Factor (EF) and geoaccumulation index (Igeo) can be applied. These indexes are used to assess the presence and intensity of anthropogenic contaminant deposition on surface soil
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
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