130,494 research outputs found
Where Fail-Safe Default Logics Fail
Reiter's original definition of default logic allows for the application of a
default that contradicts a previously applied one. We call failure this
condition. The possibility of generating failures has been in the past
considered as a semantical problem, and variants have been proposed to solve
it. We show that it is instead a computational feature that is needed to encode
some domains into default logic
Can Hamiltonians be boundary observables in Parametrized Field Theories?
It has been argued that holography in gravitational theories is related to
the existence of a particularly useful Gauss Law that allows energy to be
measured at the boundary. The present work investigates the extent to which
such Gauss Laws follow from diffeomorphism invariance. We study parametrized
field theories, which are a class of diffeomorphism-invariant theories without
gravity. We find that the Hamiltonian for parametrized field theories vanishes
on shell even in the presence of a boundary and under a variety of boundary
conditions. We conclude that parametrized theories have no useful Gauss Law,
consistent with the absence of holography in these theories.Comment: 28 pages, LaTeX, references added, citations clarified, typos
correcte
Let's Twist Again: N=2 Super Yang Mills Theory Coupled To Matter
We give the twisted version of N=2 Super Yang Mills theory coupled to matter,
including quantum fields, supersymmetry transformations, action and algebraic
structure. We show that the whole action, coupled to matter, can be written as
the variation of a nilpotent operator, modulo field equations. An extended
Slavnov-Taylor identity, collecting gauge symmetry and supersymmetry, is
written, which allows to define the web of algebraic constraints, in view of
the algebraic renormalization and of the extension of the non-renormalization
theorems holding for N=2 SYM theory without matter.Comment: 28 pages, final version to be published on CQ
Translations and dynamics
We analyze the role played by local translational symmetry in the context of
gauge theories of fundamental interactions. Translational connections and
fields are introduced, with special attention being paid to their universal
coupling to other variables, as well as to their contributions to field
equations and to conserved quantities.Comment: 22 Revtex pages, no figures. Published version with minor correction
Towards MKM in the Large: Modular Representation and Scalable Software Architecture
MKM has been defined as the quest for technologies to manage mathematical
knowledge. MKM "in the small" is well-studied, so the real problem is to scale
up to large, highly interconnected corpora: "MKM in the large". We contend that
advances in two areas are needed to reach this goal. We need representation
languages that support incremental processing of all primitive MKM operations,
and we need software architectures and implementations that implement these
operations scalably on large knowledge bases.
We present instances of both in this paper: the MMT framework for modular
theory-graphs that integrates meta-logical foundations, which forms the base of
the next OMDoc version; and TNTBase, a versioned storage system for XML-based
document formats. TNTBase becomes an MMT database by instantiating it with
special MKM operations for MMT.Comment: To appear in The 9th International Conference on Mathematical
Knowledge Management: MKM 201
A Field Range Bound for General Single-Field Inflation
We explore the consequences of a detection of primordial tensor fluctuations
for general single-field models of inflation. Using the effective theory of
inflation, we propose a generalization of the Lyth bound. Our bound applies to
all single-field models with two-derivative kinetic terms for the scalar
fluctuations and is always stronger than the corresponding bound for slow-roll
models. This shows that non-trivial dynamics can't evade the Lyth bound. We
also present a weaker, but completely universal bound that holds whenever the
Null Energy Condition (NEC) is satisfied at horizon crossing.Comment: 16 page
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