8,721 research outputs found
Multiderivations of Coxeter arrangements
Let be an -dimensional Euclidean space. Let be a
finite irreducible orthogonal reflection group. Let be the
corresponding Coxeter arrangement. Let be the algebra of polynomial
functions on For choose such that For each nonnegative integer , define the derivation
module \sD^{(m)}({\cal A}) = \{\theta \in {\rm Der}_S | \theta(\alpha_H) \in S
\alpha^m_H\}. The module is known to be a free -module of rank by K.
Saito (1975) for and L. Solomon-H. Terao (1998) for . The main
result of this paper is that this is the case for all . Moreover we
explicitly construct a basis for \sD^{(m)} (\cal A). Their degrees are all
equal to (when is even) or are equal to (when is odd). Here are the
exponents of and is the Coxeter number. The construction
heavily uses the primitive derivation which plays a central role in the
theory of flat generators by K. Saito (or equivalently the Frobenius manifold
structure for the orbit space of .) Some new results concerning the
primitive derivation are obtained in the course of proof of the main
result.Comment: dedication and a footnote (thanking a grant) adde
Higgs and Top quark coupled with a conformal gauge sector
We propose a dynamical scenario beyond the standard model, in which the
radiative correction to the Higgs mass parameter is suppressed due to a large
anomalous dimension induced through a conformal invariant coupling with an
extra gauge sector. Then the anomalous dimension also suppresses the Yukawa
couplings of the Higgs field. However, the large top Yukawa coupling can be
generated effectively through mixing among top quarks and the fermions of the
conformal gauge sector. This scenario is found to predict a fairly heavy Higgs
mass of about 500 GeV. We present an explicit model and show consistency with
the Electro-Weak precision measurements of the S and T parameters as well as
the Z boson decay width.Comment: 12 pages, 3 Postscript figures, uses RevTex.sty; corrected typos and
reference
Two Dimensional Black Hole Evapolation in the Light-Cone Gauge
Quantization of the pure dimensional dilaton gravity is examined in the
light-cone gauge. It is found that the total action including ghosts generates
a free conformal field theory without modification of the classical
action, which is required in the conformal gauge. We also study semiclassical
equations of the dilaton gravity coupled to scalar fields. It is shown that
the black hole singularity is not removed even for in the light-cone
gauge. This indicates that the semiclassical analysis breaks down for small
.Comment: 10 pages, KANAZAWA-92-1
Algebras generated by reciprocals of linear forms
Let be a finite set of nonzero linear forms in several variables
with coefficients in a field of characteristic zero. Consider the
-algebra of rational functions generated by . Then the ring of differential
operators with constant coefficients naturally acts on . We study
the graded -module structure of . We especially find
standard systems of minimal generators and a combinatorial formula for the
Poincar\'e series of . Our proofs are based on a theorem by
Brion-Vergne [brv1] and results by Orlik-Terao [ort2}.Comment: a typo corrected; a footnote adde
Exchange and spin Jahn-Teller distortions for a triangular cluster of spin-1/2
We study the effects of magnetoelastic coupling on the degenerate ground
state of the spin-1/2 antiferromagnetic Heisenberg model for the regular
triangular spin cluster. Static displacement of spins spontaneously lifts the
degeneracy of the ground state through the distance dependence of exchange
coupling, i.e., a spin Jahn-Teller mechanism takes place. On the other hand,
dynamical displacement does not lift the degeneracy, though the cluster
distorts spontaneously. The energy decrease obtained by dynamical theory is
twice as large as that obtained by static theory because of quantum
fluctuation.Comment: 4 pages, 1 figure. Accepted by JPSJ. Clarified some setences.
Corrected typo
An Institutional Analysis of Environmental Pollution Disputes in Taiwan: Cases of 'Self-Relief'
During the late 1980s and early 1990s in Taiwan, people's protests against environmental pollution often took the form of "self-relief," meaning that they attempted to fight polluters using their own resources, without relying on legal or administrative procedures. Why did such an extreme form of disputes become so widespread? What institutional changes did these movements bring about? These questions are analyzed using the analytical framework of "law and economics." Our research shows that "self-relief" functioned to a certain extent as a means of realizing quick compensation for victims, and for reflecting the opinions of local people concerning development projects; in addition, it served to promote the formulation of law and administrative systems. However, as it was based on direct negotiations between the parties concerned, the outcome of each dispute only reflected the transient balance of forces, and the experience gained in negotiations was not accumulated as a social norm.Environmental problems, Pollution, Democratization, Taiwan
The Shi arrangements and the Bernoulli polynomials
The braid arrangement is the Coxeter arrangement of the type . The
Shi arrangement is an affine arrangement of hyperplanes consisting of the
hyperplanes of the braid arrangement and their parallel translations. In this
paper, we give an explicit basis construction for the derivation module of the
cone over the Shi arrangement. The essential ingredient of our recipe is the
Bernoulli polynomials.Comment: We fixed a typ
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