99,201 research outputs found
Special scrolls whose base curve has general moduli
In this paper we study the Hilbert scheme of smooth, linearly normal, special
scrolls under suitable assumptions on degree, genus and speciality.Comment: Latex2e, shorter versio
Seminatural bundles of rank two, degree one and on a quintic surface
In this paper we continue our study of the moduli space of stable bundles of
rank two and degree 1 on a very general quintic surface. The goal in this paper
is to understand the irreducible components of the moduli space in the first
case in the "good" range, which is . We show that there is a single
irreducible component of bundles which have seminatural cohomology, and
conjecture that this is the only component for all stable bundles
Elliptic curve configurations on Fano surfaces
The elliptic curves on a surface of general type constitute an obstruction
for the cotangent sheaf to be ample. In this paper, we give the classification
of the configurations of the elliptic curves on the Fano surface of a smooth
cubic threefold. That means that we give the number of such curves, their
intersections and a plane model. This classification is linked to the
classification of the automorphism groups of theses surfaces.Comment: 17 pages, accepted and shortened version, the rest will appear in
"Fano surfaces with 12 or 30 elliptic curves
Chiral SUSY Theories with a Suppressed SUSY Charge
The well-known Chiral and Gauge SUSY Actions realize the SUSY charge in terms
of transformations among the Fields. These transformations are included in the
Master Equation by coupling them to Sources. Here we show that there are new
local SUSY Actions where the Chiral SUSY transformations are realized in terms
of transformations among both Fields and Sources. These Actions can be easily
obtained from the Chiral case by a very simple and local `Exchange
Transformation', which carries along all the interactions without difficulty.
For these new SUSY Actions, the SUSY charge does not exist in the relevant
sector, because Sources do not satisfy Equations of Motion.
Nevertheless, the `Exchange Transformation' ensures that the new Master
Equation is true for the new Action. As a consequence, the Master Equation also
is true for the new 1PI Generating Functional. This implies that a `Suppressed
SUSY Charge' version of SUSY is still present. SUSY certainly becomes more
obscure and less constrained in this case. But it is still very restrictive.
The new theories can be obtained from the old theories by using a special
technique, but it is not true that they are a sort of `broken version of
supersymmetry'. They are simply a new type of theory that is governed by
Supersymmetry, but without the use of Supercharges (except perhaps in some
sectors).
In particular the number of physical Bosonic and Fermionic degrees of Freedom
are not equal for these new (sub)-Actions, although there is still
Boson/Fermion mass degeneracy in a (sub)-Action, so long as there is still a
Boson present. Notably, there is even a SUSY (sub)-Action where the physical
Scalars are not present, so that the (sub)-Action contains physical Fermions
only. In this theory the degeneracy of Bosonic and Fermionic masses is
obviously not present.Comment: 21 pages This version has a better explanation of how and why these
new representations of SUSY can and do exist, without contradicting the known
results in SUSY theor
A uniform definition of stochastic process calculi
We introduce a unifying framework to provide the semantics of process algebras, including their quantitative variants useful for modeling quantitative aspects of behaviors. The unifying framework is then used to describe some of the most representative stochastic process algebras. This
provides a general and clear support for an understanding of their similarities and differences. The framework is based on State to Function Labeled Transition Systems, FuTSs for short, that are state-transition structures where each transition is a triple of the form (s; Ī±;P). The first andthe second components are the source state, s, and the label, Ī±, of the transition, while the third component is the continuation function, P, associating a value of a suitable type to each state s0. For example, in the case of stochastic process algebras the value of the continuation function on s0 represents the rate of the negative exponential distribution characterizing the duration/delay of the action performed to reach state s0 from s. We first provide the semantics of a simple formalism used to describe Continuous-Time Markov Chains, then we model a number of process algebras that permit parallel composition of models according to the two main interaction paradigms (multiparty and one-to-one synchronization). Finally, we deal with formalisms where actions and rates are kept separate and address the issues related to the coexistence of stochastic, probabilistic, and non-deterministic behaviors. For each formalism, we establish the formal correspondence between the FuTSs semantics and its original semantics
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