111 research outputs found
Locality and Translations in Braided Ribbon Networks
An overview of microlocality in braided ribbon networks is presented.
Following this, a series of definitions are presented to explore the concept of
microlocality and the topology of ribbon networks. Isolated substructure of
ribbon networks are introduced, and a theorem is proven that allows them to be
relocated. This is followed by a demonstration of microlocal translations.
Additionally, an investigation into macrolocality and the implications of
invariants in braided ribbon networks are presented.Comment: 12 pages, 12 figure
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The Role of National Debts in the Determination of the Yen-Dollar Exchange Rate
An intertemporal optimization model is developed to examine the determinants of the long-run nominal yen-dollar exchange rate in the presence of national debts. The model is tested empirically using data from Japan and the USA. The proposed theoretical specification is well supported by the data and shows that relative national debts as well as monetary and financial factors may play a significant role in the determination of the long-run nominal exchange rate between the yen and the dollar
Quantum gravity and the standard model
We show that a class of background independent models of quantum spacetime
have local excitations that can be mapped to the first generation fermions of
the standard model of particle physics. These states propagate coherently as
they can be shown to be noiseless subsystems of the microscopic quantum
dynamics. These are identified in terms of certain patterns of braiding of
graphs, thus giving a quantum gravitational foundation for the topological
preon model proposed by one of us.
These results apply to a large class of theories in which the Hilbert space
has a basis of states given by ribbon graphs embedded in a three-dimensional
manifold up to diffeomorphisms, and the dynamics is given by local moves on the
graphs, such as arise in the representation theory of quantum groups. For such
models, matter appears to be already included in the microscopic kinematics and
dynamics.Comment: 12 pages, 21 figures, improved presentation, results unchange
Conserved Quantities in Background Independent Theories
We discuss the difficulties that background independent theories based on
quantum geometry encounter in deriving general relativity as the low energy
limit. We follow a geometrogenesis scenario of a phase transition from a
pre-geometric theory to a geometric phase which suggests that a first step
towards the low energy limit is searching for the effective collective
excitations that will characterize it. Using the correspondence between the
pre-geometric background independent theory and a quantum information
processor, we are able to use the method of noiseless subsystems to extract
such coherent collective excitations. We illustrate this in the case of locally
evolving graphs.Comment: 11 pages, 3 figure
Hadron Properties with FLIC Fermions
The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of
nonperturbative O(a)-improvement in lattice fermion actions offering near
continuum results at finite lattice spacing. It provides computationally
inexpensive access to the light quark mass regime of QCD where chiral
nonanalytic behaviour associated with Goldstone bosons is revealed. The
motivation and formulation of FLIC fermions, its excellent scaling properties
and its low-lying hadron mass phenomenology are presented.Comment: 29 pages, 13 figures, 6 tables. Contribution to lecure notes in 2nd
Cairns Topical Workshop on Lattice Hadron Physics 2003 (LHP 2003), Cairns,
Australia, 22-30 Jul 200
Excited Baryons in Lattice QCD
We present first results for the masses of positive and negative parity
excited baryons calculated in lattice QCD using an O(a^2)-improved gluon action
and a fat-link irrelevant clover (FLIC) fermion action in which only the
irrelevant operators are constructed with APE-smeared links. The results are in
agreement with earlier calculations of N^* resonances using improved actions
and exhibit a clear mass splitting between the nucleon and its chiral partner.
An correlation matrix analysis reveals two low-lying J^P=(1/2)^- states with a
small mass splitting. The study of different Lambda interpolating fields
suggests a similar splitting between the lowest two Lambda1/2^- octet states.
However, the empirical mass suppression of the Lambda^*(1405) is not evident in
these quenched QCD simulations, suggesting a potentially important role for the
meson cloud of the Lambda^*(1405) and/or a need for more exotic interpolating
fields.Comment: Correlation matrix analysis performed. Increased to 400
configurations. 22 pages, 13 figures, 15 table
Numerical study of lattice index theorem usingimproved cooling and overlap fermions
We investigate topological charge and the index theorem on finite lattices
numerically. Using mean field improved gauge field configurations we calculate
the topological charge Q using the gluon field definition with -improved cooling and an -improved field strength tensor
. We also calculate the index of the massless overlap fermion
operator by directly measuring the differences of the numbers of zero modes
with left- and right--handed chiralities. For sufficiently smooth field
configurations we find that the gluon field definition of the topological
charge is integer to better than 1% and furthermore that this agrees with the
index of the overlap Dirac operator, i.e., the Atiyah-Singer index theorem is
satisfied. This establishes a benchmark for reliability when calculating
lattice quantities which are very sensitive to topology.Comment: 15 pages, 1 figure
Entanglement Entropy from a Holographic Viewpoint
The entanglement entropy has been historically studied by many authors in
order to obtain quantum mechanical interpretations of the gravitational
entropy. The discovery of AdS/CFT correspondence leads to the idea of
holographic entanglement entropy, which is a clear solution to this important
problem in gravity. In this article, we would like to give a quick survey of
recent progresses on the holographic entanglement entropy. We focus on its
gravitational aspects, so that it is comprehensible to those who are familiar
with general relativity and basics of quantum field theory.Comment: Latex, 30 pages, invited review for Classical and Quantum Gravity,
minor correction
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