15,511 research outputs found
Dynamic Critical Behavior of Percolation Observables in the 2d Ising Model
We present preliminary results of our numerical study of the critical
dynamics of percolation observables for the two-dimensional Ising model. We
consider the (Monte-Carlo) short-time evolution of the system obtained with a
local heat-bath method and with the global Swendsen-Wang algorithm. In both
cases, we find qualitatively different dynamic behaviors for the magnetization
and Omega, the order parameter of the percolation transition. This may have
implications for the recent attempts to describe the dynamics of the QCD phase
transition using cluster observables.Comment: 3 pages, 1 figur
Sectional curvature and Weitzenb\"ock formulae
We establish a new algebraic characterization of sectional curvature bounds
and using only curvature terms in the Weitzenb\"ock
formulae for symmetric -tensors. By introducing a symmetric analogue of the
Kulkarni-Nomizu product, we provide a simple formula for such curvature terms.
We also give an application of the Bochner technique to closed -manifolds
with indefinite intersection form and or , obtaining new
insights into the Hopf Conjecture, without any symmetry assumptions.Comment: LaTeX2e, 25 pages, final version. To appear in Indiana Univ. Math.
Strongly positive curvature
We begin a systematic study of a curvature condition (strongly positive
curvature) which lies strictly between positive curvature operator and positive
sectional curvature, and stems from the work of Thorpe in the 1970s. We prove
that this condition is preserved under Riemannian submersions and Cheeger
deformations, and that most compact homogeneous spaces with positive sectional
curvature satisfy it.Comment: LaTeX2e, 26 page
Spinors Fields in Co-dimension One Braneworlds
In this work we analyze the zero mode localization and resonances of
spin fermions in co-dimension one Randall-Sundrum braneworld scenarios.
We consider delta-like, domain walls and deformed domain walls membranes.
Beyond the influence of the spacetime dimension we also consider three
types of couplings: (i) the standard Yukawa coupling with the scalar field and
parameter , (ii) a Yukawa-dilaton coupling with two parameters
and and (iii) a dilaton derivative coupling with parameter .
Together with the deformation parameter , we end up with five free parameter
to be considered. For the zero mode we find that the localization is dependent
of , because the spinorial representation changes when the bulk
dimensionality is odd or even and must be treated separately. For case (i) we
find that in odd dimensions only one chirality can be localized and for even
dimension a massless Dirac spinor is trapped over the brane. In the cases (ii)
and (iii) we find that for some values of the parameters, both chiralities can
be localized in odd dimensions and for even dimensions we obtain that the
massless Dirac spinor is trapped over the brane. We also calculated numerically
resonances for cases (ii) and (iii) by using the transfer matrix method. We
find that, for deformed defects, the increasing of induces a shift in the
peaks of resonances. For a given with domain walls, we find that the
resonances can show up by changing the spacetime dimensionality. For example,
the same case in do not induces resonances but when we consider
one peak of resonance is found. Therefore the introduction of more dimensions,
diversely from the bosonic case, can change drastically the zero mode and
resonances in fermion fields.Comment: 28 pages, 7 figure
Symbolic Sequences and Tsallis Entropy
We address this work to investigate symbolic sequences with long-range
correlations by using computational simulation. We analyze sequences with two,
three and four symbols that could be repeated times, with the probability
distribution . For these sequences, we verified that
the usual entropy increases more slowly when the symbols are correlated and the
Tsallis entropy exhibits, for a suitable choice of , a linear behavior. We
also study the chain as a random walk-like process and observe a nonusual
diffusive behavior depending on the values of the parameter .Comment: Published in the Brazilian Journal of Physic
Cartoon planet: Micro-reflection through digital cartoons - a case study on teaching and learning with young people
The young learners of today tend to show little enthusiasm for formal schooling. This does not
necessarily mean pupils are not interested in learning or developing new skills and competences. In
fact, the opposite often happens in the informal settings they belong to. Finding ways of transferring
pupil’s informal learning to the school setting is therefore important. This paper gives a brief overview
on the development of informal learning activities to encourage young people’s active reflection on
their informally acquired competencies through the use of web technologies. The researchers also
explore the role of the teacher, and the need of a participatory learning environment in a less formal
classroom. Reflections on the experiences and recommendations are also provided
Entanglement guided search for parent Hamiltonians
We introduce a method for the search of parent Hamiltonians of input
wave-functions based on the structure of their reduced density matrix. The two
key elements of our recipe are an ansatz on the relation between reduced
density matrix and parent Hamiltonian that is exact at the field theory level,
and a minimization procedure on the space of relative entropies, which is
particularly convenient due to its convexity. As examples, we show how our
method correctly reconstructs the parent Hamiltonian correspondent to several
non-trivial ground state wave functions, including conformal and
symmetry-protected-topological phases, and quantum critical points of
two-dimensional antiferromagnets described by strongly coupled field theories.
Our results show the entanglement structure of ground state wave-functions
considerably simplifies the search for parent Hamiltonians.Comment: 5 pages, 5 figures, supplementary materia
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