3,653 research outputs found
Three-particle correlations in QCD jets and beyond
In this paper, we present a more detailed version of our previous work for
three-particle correlations in quark and gluon jets [1]. We give theoretical
results for this observable in the double logarithmic approximation and the
modified leading logarithmic approximation. In both resummation schemes, we use
the formalism of the generating functional and solve the evolution equations
analytically from the steepest descent evaluation of the one-particle
distribution. In addition, in this paper we include predictions beyond the
limiting spectrum approximation and study this observable near the hump of the
single inclusive distribution. We thus provide a further test of the local
parton hadron duality (LPHD) and make predictions for the LHC. The computation
of higher rank correlators is presented in the double logarithmic approximation
and shown to be rather cumbersome.Comment: 34 pages and 14 figure
PSUDOC - A Simple Diagnostic Program
This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-C-0643.This paper describes PSUDOC, a very simple LISP program to carry out some medical diagnosis tasks. The program's domain is a subset of clinical medicine characterized by patients presenting with edema and/or hematuria. The program's goal is to go from the presenting symptoms to a hypothesis of the underlying disease state. The program uses a variation of simple tree searching strategies called ETS.MIT Artificial Intelligence Laboratory
Department of Defense Advanced Research Projects Agenc
Quantification of environmentally-assisted cracking mechanisms with high- resolution characterisation
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Depinning and dynamics of AC driven vortex lattices in random media
We study the different dynamical regimes of a vortex lattice driven by AC
forces in the presence of random pinning via numerical simulations. The
behaviour of the different observables is charaterized as a function of the
applied force amplitude for different frequencies. We discuss the
inconveniences of using the mean velocity to identify the depinnig transition
and we show that instead, the mean quadratic displacement of the lattice is the
relevant magnitude to characterize different AC regimes. We discuss how the
results depend on the initial configuration and we identify new hysteretic
effects which are absent in the DC driven systems.Comment: 6 pages, 4 figure
Temporal Correlations and Persistence in the Kinetic Ising Model: the Role of Temperature
We study the statistical properties of the sum , that is the difference of time spent positive or negative by the
spin , located at a given site of a -dimensional Ising model
evolving under Glauber dynamics from a random initial configuration. We
investigate the distribution of and the first-passage statistics
(persistence) of this quantity. We discuss successively the three regimes of
high temperature (), criticality (), and low temperature
(). We discuss in particular the question of the temperature
dependence of the persistence exponent , as well as that of the
spectrum of exponents , in the low temperature phase. The
probability that the temporal mean was always larger than the
equilibrium magnetization is found to decay as . This
yields a numerical determination of the persistence exponent in the
whole low temperature phase, in two dimensions, and above the roughening
transition, in the low-temperature phase of the three-dimensional Ising model.Comment: 21 pages, 11 PostScript figures included (1 color figure
Visible Decomposition: Real-Time Path Planning in Large Planar Environments
We describe a method called Visible Decomposition for computing collision-free paths in real time through a planar environment with a large number of obstacles. This method divides space into local visibility graphs, ensuring that all operations are local. The search time is kept low since the number of regions is proved to be small. We analyze the computational demands of the algorithm and the quality of the paths it produces. In addition, we show test results on a large simulation testbed
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