366 research outputs found
De kust van nature - 1500 tot 2100: referatenboek van de studiedag, Oostende, 13 november 2012
Geophysical Research
Contains reports on two research projects.National Aeronautics and Space Administration (Grant NGR-22-009-131)National Aeronautics and Space Administration (Grant NGR-22-009-114)National Aeronautics and Space Administration (Contract NAS 12-436
Moet er nog zand zijn: een wetenschappelijke kijk op de kustlijn van morgen. Bredene, België, 24 mei 2011: Referatenbundel van de studiedag
Universal behavior of multiplicity differences in quark-hadron phase transition
The scaling behavior of factorial moments of the differences in
multiplicities between well separated bins in heavy-ion collisions is proposed
as a probe of quark-hadron phase transition. The method takes into account some
of the physical features of nuclear collisions that cause some difficulty in
the application of the usual method. It is shown in the Ginzburg-Landau theory
that a numerical value of the scaling exponent can be determined
independent of the parameters in the problem. The universality of
characterizes quark-hadron phase transition, and can be tested directly by
appropriately analyzed data.Comment: 15 pages, including 4 figures (in epsf file), Latex, submitted to
Phys. Rev.
A Color Mutation Model of Soft Interaction in High Energy Hadronic Collisions
A comprehensive model, called ECOMB, is proposed to describe multiparticle
production by soft interaction. It incorporates the eikonal formalism, parton
model, color mutation, branching and recombination. The physics is conceptually
opposite to the dynamics that underlies the fragmentation of a string. The
partons are present initially in a hadronic collision; they form a single,
large, color-neutral cluster until color mutation of the quarks leads to a
fission of the cluster into two color-neutral subclusters. The mutation and
branching processes continue until only pairs are left in each small
cluster. The model contains self-similar dynamics and exhibits scaling behavior
in the factorial moments. It can satisfactorily reproduce the intermittency
data that no other model has been able to fit.Comment: 24 pages including 11 figures in revtex epsf styl
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Search for MSSM Higgs bosons decaying to μ+μ-in proton-proton collisions at √s=13TeV
A search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13TeVwere used, corresponding to an integrated luminosity of 35.9fb-1. The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a bbquark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the mmod+hand phenomenological MSSM scenarios on the parameter tanβas a function of the mass of the pseudoscalar Aboson, in the range from 130 to 600GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with bquarks, in the mass range from 130 to 1000GeV
Modified Gravity on the Brane and Dark Energy
We analyze the dynamics of an AdS5 braneworld with matter fields when gravity
is allowed to deviate from the Einstein form on the brane. We consider exact
5-dimensional warped solutions which are associated with conformal bulk fields
of weight -4 and describe on the brane the following three dynamics: those of
inhomogeneous dust, of generalized dark radiation, and of homogeneous
polytropic dark energy. We show that, with modified gravity on the brane, the
existence of such dynamical geometries requires the presence of non-conformal
matter fields confined to the brane.Comment: Revised version published in Gen. Rel. Grav. Typos corrected, updated
reference and some remarks added for clarity. 11 pages, latex, no figure
Organizational and dynamical aspects of a small network with two distinct communities : Neo creationists vs. Evolution Defenders
Social impacts and degrees of organization inherent to opinion formation for
interacting agents on networks present interesting questions of general
interest from physics to sociology. We present a quantitative analysis of a
case implying an evolving small size network, i.e. that inherent to the ongoing
debate between modern creationists (most are Intelligent Design (ID) proponents
(IDP)) and Darwin's theory of Evolution Defenders (DED)). This study is carried
out by analyzing the structural properties of the citation network unfolded in
the recent decades by publishing works belonging to members of the two
communities. With the aim of capturing the dynamical aspects of the interaction
between the IDP and DED groups, we focus on key quantities, namely, the
{\it degree of activity} of each group and the corresponding {\it degree of
impact} on the intellectual community at large. A representative measure of the
former is provided by the {\it rate of production of publications} (RPP),
whilst the latter can be assimilated to the{\it rate of increase in citations}
(RIC). These quantities are determined, respectively, by the slope of the time
series obtained for the number of publications accumulated per year and by the
slope of a similar time series obtained for the corresponding citations. The
results indicate that in this case, the dynamics can be seen as geared by
triggered or damped competition. The network is a specific example of marked
heterogeneity in exchange of information activity in and between the
communities, particularly demonstrated through the nodes having a high
connectivity degree, i.e. opinion leaders.Comment: 10 pages, 4 figures, 2 tables, 52 reference
Brane World Dynamics and Conformal Bulk Fields
In the Randall-Sundrum scenario we investigate the dynamics of a spherically
symmetric 3-brane world when matter fields are present in the bulk. To analyze
the 5-dimensional Einstein equations we employ a global conformal
transformation whose factor characterizes the symmetric warp. We find a
new set of exact dynamical collapse solutions which localize gravity in the
vicinity of the brane for a stress-energy tensor of conformal weight -4 and a
warp factor that depends only on the coordinate of the fifth dimension.
Geometries which describe the dynamics of inhomogeneous dust and generalized
dark radiation on the brane are shown to belong to this set. The conditions for
singular or globally regular behavior and the static marginally bound limits
are discussed for these examples. Also explicitly demonstrated is complete
consistency with the effective point of view of a 4-dimensional observer who is
confined to the brane and makes the same assumptions about the bulk degrees of
freedom.Comment: 26 pages, latex, no figures. Minor revisions. Some references added.
Revised version to appear in Phys. Rev.
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