14,287 research outputs found
Noncommutativity Approach to Supersymmetry on the Lattice: SUSY Quantum Mechanics and an Inconsistency
It is argued that the noncommutativity approach to fully supersymmetric field
theories on the lattice suffers from an inconsistency. Supersymmetric quantum
mechanics is worked out in this formalism and the inconsistency is shown both
in general and explicitly for that system, as well as for the Abelian super BF
model.Comment: 8 pages, typo's corrected, conclusions unchange
On Multivariate Records from Random Vectors with Independent Components
Let be independent copies of a
random vector with values in and with a
continuous distribution function. The random vector is a
complete record, if each of its components is a record. As we require
to have independent components, crucial results for univariate
records clearly carry over. But there are substantial differences as well:
While there are infinitely many records in case , there occur only
finitely many in the series if . Consequently, there is a terminal
complete record with probability one. We compute the distribution of the random
total number of complete records and investigate the distribution of the
terminal record. For complete records, the sequence of waiting times forms a
Markov chain, but differently from the univariate case, now the state infinity
is an absorbing element of the state space
Some Results on Joint Record Events
Let be independent and identically distributed random
variables on the real line with a joint continuous distribution function .
The stochastic behavior of the sequence of subsequent records is well known.
Alternatively to that, we investigate the stochastic behavior of arbitrary
, under the condition that they are records, without knowing their
orders in the sequence of records. The results are completely different. In
particular it turns out that the distribution of , being a record, is not
affected by the additional knowledge that is a record as well. On the
contrary, the distribution of , being a record, is affected by the
additional knowledge that is a record as well. If has a density, then
the gain of this additional information, measured by the corresponding
Kullback-Leibler distance, is , independent of . We derive the limiting
joint distribution of two records, which is not a bivariate extreme value
distribution. We extend this result to the case of three records. In a special
case we also derive the limiting joint distribution of increments among
records
Semantic browsing of digital collections
Visiting museums is an increasingly popular pastime. Studies have shown that visitors can draw on their museum experience, long after their visit, to learn new things in practical situations. Rather than viewing a visit as a
single learning event, we are interested in ways of extending the experience to allow visitors to access online resources tailored to their interests. Museums
typically have extensive archives that can be made available online, the challenge is to match these resources to the visitor’s interests and present them in a manner that facilitates exploration and engages the visitor. We propose the use of knowledge level resource descriptions to identify relevant resources and create structured presentations. A system that embodies this approach, which is in use in a UK museum, is presented and the applicability of the approach to the broader semantic web is discussed
Observation of a Broad L=1 State in at CLEO
Using 4.7 fb^-1 of data taken at CESR at energies at and near the Upsilon(4S)
we have studied the decay B- -> D{*+}pi-pi- (and its conjugate). We observe a
new, broad charmed meson state, which we interpret as D_J(j=1/2), in its decay
to D{*+}pi-. Our preliminary results indicate the mass and width of this L=1
state to be m = (2461 +41/-3} +/-10 +/-32) MeV and Gamma = (290 +101/-79 +/-26
+/-36) MeV, with the third uncertainty associated with the parameterization of
the relative strong phases. In addition we have measured several new branching
fractions of charged B mesons. All quoted results are preliminary.Comment: 7 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Mixed finite element methods for linear elasticity with weakly imposed symmetry
In this paper, we construct new finite element methods for the approximation
of the equations of linear elasticity in three space dimensions that produce
direct approximations to both stresses and displacements. The methods are based
on a modified form of the Hellinger--Reissner variational principle that only
weakly imposes the symmetry condition on the stresses. Although this approach
has been previously used by a number of authors, a key new ingredient here is a
constructive derivation of the elasticity complex starting from the de Rham
complex. By mimicking this construction in the discrete case, we derive new
mixed finite elements for elasticity in a systematic manner from known
discretizations of the de Rham complex. These elements appear to be simpler
than the ones previously derived. For example, we construct stable
discretizations which use only piecewise linear elements to approximate the
stress field and piecewise constant functions to approximate the displacement
field.Comment: to appear in Mathematics of Computatio
- …