23,532 research outputs found
A quantitative sharpening of Moriwaki's arithmetic Bogomolov inequality
A. Moriwaki proved the following arithmetic analogue of the Bogomolov
unstability theorem. If a torsion-free hermitian coherent sheaf on an
arithmetic surface has negative discriminant then it admits an arithmetically
destabilising subsheaf. In the geometric situation it is known that such a
subsheaf can be found subject to an additional numerical constraint and here we
prove the arithmetic analogue. We then apply this result to slightly simplify a
part of C. Soul\'e's proof of a vanishing theorem on arithmetic surfaces.Comment: final version, to appear in Math. Res. Let
Some aspects of the ecology of the limnoplankton, with special reference to the phytoplankton. [Translation from: Svensk Botanisk Tidskrift 13(2) 129-163, 1919.]
This paper tries to develop more generally some fundamental bases for the ecological study of freshwater plankton. A special attention is given to the phytoplankton associations which can be separated out and made into groups according to their dependence upon changing environments. Plankton formations in different types of water bodies (ponds, lakes and rivers) are studied
Arithmetically defined dense subgroups of Morava stabilizer groups
For every prime and integer we explicitly construct an abelian
variety A/\F_{p^n} of dimension such that for a suitable prime the
group of quasi-isogenies of A/\F_{p^n} of -power degree is canonically a
dense subgroup of the -th Morava stabilizer group at . We also give a
variant of this result taking into account a polarization. This is motivated by
a perceivable generalization of topological modular forms to more general
topological automorphic forms. For this, we prove some results about
approximation of local units in maximal orders which is of independent
interest. For example, it gives a precise solution to the problem of extending
automorphisms of the -divisible group of a simple abelian variety over a
finite field to quasi-isogenies of the abelian variety of degree divisible by
as few primes as possible.Comment: major revision, main results slightly changed; final version, to
appear in Compositio Mat
Probing QCD Parameters with Top-Quark Data
Results from inclusive and differential measurements of the production cross
sections for top quarks in proton-proton collisions at center-of-mass energies
of 7 and 8 TeV are compared to predictions at next-to-leading and
next-to-next-to-leading order in perturbative Quantum Chromodynamics. From
these studies, constraints on the top-quark mass, the strong coupling constant,
and on parton distributions functions are determined.Comment: 8 pages, 11 figures, to appear in the proceedings of the 6th
International Workshop on Top Quark Physics (TOP2013
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