331 research outputs found
Monodromy zeta functions at infinity, Newton polyhedra and constructible sheaves
By using sheaf-theoretical methods such as constructible sheaves, we
generalize the formula of Libgober-Sperber concerning the zeta functions of
monodromy at infinity of polynomial maps into various directions. In
particular, some formulas for the zeta functions of global monodromy along the
fibers of bifurcation points of polynomial maps will be obtained.Comment: 31 pages; revise
A geometric degree formula for A-discriminants and Euler obstructions of toric varieties
AbstractWe give explicit formulas for the dimensions and the degrees of A-discriminant varieties introduced by Gelfand, Kapranov and Zelevinsky. Our formulas can be applied also to the case where the A-discriminant varieties are higher-codimensional and their degrees are described by the geometry of the configurations A. Moreover combinatorial formulas for the Euler obstructions of general (not necessarily normal) toric varieties will be also given
Was Martian mantle wet? A possible consequence of rapid core formation
Degassing of H2O in the planetary interior possibly plays an important role in the evolution of surface environment as well as geologic activity on the terrestrial planets. Mars may be such a planet that well preserves the materials and the geologic features directly related to early evolution of H2O. H2O content in the interior of proto-Mars during accretion and also core formation were investigated. Geodetic data shows that Mars has a dense core. The existence of iron-rich core on Mars may be also supported by the depletion of siderophile elements in SNC meteorites assuming that these samples came from Mars. Isotope systematics of these meteorites indicate that the core formation occurred very early, probably concurrently with Mars formation. Considering the kinetics of metal segregation from silicate, the melting of silicate is likely to precede the core formation. Once the core formation occurs, substantial amount of gravitational energy is released and thus the planetary interior is heated. This energy may be large enough to keep the silicate material in partially molten state along with the accretional heating. Under such circumstances, the silicate melt probably migrates to the surface. Early crustal formation, therefore, is also likely to be associated with the core formation
Hadronic decays of in the perturbative QCD approach
We calculate the branching ratios and polarization fractions of the decays in the perturbative QCD(pQCD) approach at leading order, where
() stands for the axial-vector state. By
combining the phenomenological analyses with the perturbative calculations, we
find the following results: (a) the large decay rates around to
of the decays dominated by the longitudinal
polarization(except for the mode) are predicted and
basically consistent with those in the QCD factorization(QCDF) within errors,
which are expected to be tested by the Large Hadron Collider and Belle-II
experiments. The large branching ratio could provide
hints to help explore the mechanism of the color-suppressed decays. (b) the
rather different QCD behaviors between the and mesons result in the
destructive(constructive) contributions in the nonfactorizable spectator
diagrams with emission. Therefore, an interesting pattern of the
branching ratios appears for the color-suppressed and modes in the pQCD approach, , which is different
from in the QCDF and would be verified at future experiments. (c) the
large naive factorization breaking effects are observed in these decays. Specifically, the large nonfactorizable spectator(weak
annihilation) amplitudes contribute to the mode(s), which demand confirmations
via the precise measurements.Comment: 13 pages, 1 figure, 5 tables, revtex fil
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