3,253 research outputs found
Two particle correlation measurements at PHENIX
Measurements of two particle azimuthal correlations in relativistic heavy ion
collisions are useful tools to dissect the interplay between hard-scattered
partons and hot dense medium. Correlations with trigger particle selection
relative to second order event plane are sensitive to the path-length
dependence of parton energy loss and to the influence of the medium on jet for
high and intermediate transverse momenta pairs, respectively. To study the
parton-medium coupling, it is also crucial to obtain correlations with
rejection of contributions from higher harmonic flow. We present current
results of second order event plane dependent correlations as well as
correlations in which contributions from higher harmonic flow have been
excluded in Au+Au collisions at GeV measured by PHENIX.Comment: 4 pages, 3 figures, Hard Probes 2012 Proceeding
String operations on rational Gorenstein spaces
F\'{e}lix and Thomas developed string topology of Chas and Sullivan on
simply-connected Gorenstein spaces. In this paper, we prove that the degree
shifted homology of the free loop space of a simply-connected -Gorenstein space with rational coefficient is a non-unital and non-counital
Frobenius algebra by solving the up to constant problem. We also investigate
triviality or non-triviality of the loop product and coproduct of particular
Gorenstein spaces.Comment: 27page
Effects of additive noise on the stability of glacial cycles
It is well acknowledged that the sequence of glacial-interglacial cycles is
paced by the astronomical forcing. However, how much is the sequence robust
against natural fluctuations associated, for example, with the chaotic motions
of atmosphere and oceans? In this article, the stability of the
glacial-interglacial cycles is investigated on the basis of simple conceptual
models. Specifically, we study the influence of additive white Gaussian noise
on the sequence of the glacial cycles generated by stochastic versions of
several low-order dynamical system models proposed in the literature. In the
original deterministic case, the models exhibit different types of attractors:
a quasiperiodic attractor, a piecewise continuous attractor, strange nonchaotic
attractors, and a chaotic attractor. We show that the combination of the
quasiperiodic astronomical forcing and additive fluctuations induce a form of
temporarily quantised instability. More precisely, climate trajectories
corresponding to different noise realizations generally cluster around a small
number of stable or transiently stable trajectories present in the
deterministic system. Furthermore, these stochastic trajectories may show
sensitive dependence on very small amounts of perturbations at key times.
Consistently with the complexity of each attractor, the number of trajectories
leaking from the clusters may range from almost zero (the model with a
quasiperiodic attractor) to a significant fraction of the total (the model with
a chaotic attractor), the models with strange nonchaotic attractors being
intermediate. Finally, we discuss the implications of this investigation for
research programmes based on numerical simulators. }Comment: Parlty based on a lecture given by M. Crucifix at workshop held in
Rome in 2013 as a part of Mathematics of Planet Earth 201
Global Strong Well-posedness of the Three Dimensional Primitive equations in -spaces
In this article, an -approach to the primitive equations is developed.
In particular, it is shown that the three dimensional primitive equations admit
a unique, global strong solution for all initial data provided . To this end, the hydrostatic
Stokes operator defined on , the subspace of associated with
the hydrostatic Helmholtz projection, is introduced and investigated. Choosing
large, one obtains global well-posedness of the primitive equations for
strong solutions for initial data having less differentiability properties
than , hereby generalizing in particular a result by Cao and Titi (Ann.
Math. 166 (2007), pp. 245-267) to the case of non-smooth initial data.Comment: 26 page
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