18,769,693 research outputs found
Analysis of the Lambda p Final State Interaction in the Reaction p+p->K^+(Lambda p)
The missing mass spectrum measured in high resolution studies of the reaction
pp -> K^+X is analyzed with respect to the strong final state interaction near
the Lambda p production threshold. The observed spectrum can be described by
factorizing the reaction amplitude in terms of a production amplitude and a
final state scattering amplitude. Parametrizing the Lambda p final state
interaction in terms of the inverse Jost function allows a direct extraction of
the low-energy phase-equivalent potential parameters. Constraints on the
singlet and triplet scattering lengths and effective ranges are deduced in a
simultaneous fit of the Lambda p invariant mass spectrum and the total cross
section data of the free Lambda p scattering using the effective range
approximation.Comment: 9 pages,6 figures, 2 table
A new type of temperature driven reorientation transition in magnetic thin films
We present a new type of temperature driven spin reorientation transition
(SRT) in thin films. It can occur when the lattice and the shape anisotropy
favor different easy directions of the magnetization. Due to different
temperature dependencies of the two contributions the effective anisotropy may
change its sign and thus the direction of the magnetization as a function of
temperature may change. Contrary to the well-known reorientation transition
caused by competing surface and bulk anisotropy contributions the reorientation
that we discuss is also found in film systems with a uniform lattice
anisotropy. The results of our theoretical model study may have experimental
relevance for film systems with positive lattice anisotropy, as e.g. thin iron
films grown on copper.Comment: 7 pages, 4 figures, accepted for publication in EPJ
A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations
We use the available information on the ratio between the electric and
magnetic proton form factors coming from recently published space-like data and
from the few available time-like data. We apply a dispersive procedure on these
data to evaluate the behaviour of this ratio, as a complex function, for all
values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating,
exscale, amsmath, cite, latexsym, graphics, color packages, added reference
Experimental local realism tests without fair sampling assumption
Following the theoretical suggestion of Ref. [1,2], we present experimental
results addressed to test restricted families of local realistic models, but
without relying on the fair sampling assumption
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Transient dynamics of linear quantum amplifiers
The transient dynamics of a quantum linear amplifier during the transition
from damping to amplification regime is studied. The master equation for the
quantized mode of the field is solved, and the solution is used to describe the
statistics of the output field. The conditions under which a nonclassical input
field may retain nonclassical features at the output of the amplifier are
analyzed and compared to the results of earlier theories. As an application we
give a dynamical description of the departure of the system from thermal
equilibrium.Comment: 10 pages, 6 figures. V2: extended discussion on application
Anomalous suppression of production at large transverse momentum in Au + Au and d + Au collisions at 200 GeV
We propose a model of suppression of large -pions in heavy ion
collisions based on the interaction of the large pion with the dense
medium created in the collision. The model is practically the same as the one
previously introduced to describe suppression. Both the and the
centrality dependence of the data are reproduced. In deuteron-gold collisions,
the effect of the final state interaction with the dense medium turns out to be
negligibly small. Here the main features of the data are also reproduced both
at mid and at forward rapidities.Comment: 20 pages, latex, 3 postscript figures. Last version, to be published
in EJP
Generic theory of active polar gels: a paradigm for cytoskeletal dynamics
We develop a general theory for active viscoelastic materials made of polar
filaments. This theory is motivated by the dynamics of the cytoskeleton. The
continuous consumption of a fuel generates a non equilibrium state
characterized by the generation of flows and stresses. Our theory can be
applied to experiments in which cytoskeletal patterns are set in motion by
active processes such as those which are at work in cells.Comment: 28 pages, 2 figure
Lepton flavor violating Z-decays in supersymmetric see-saw model
In supersymmetric see-saw model, the large flavor mixings of sleptons induce
the lepton flavor violating (LFV) interactions
(), which give rise to various LFV processes. In this work we
examine the induced LFV decays . Subject to the
constraints from the existing neutrino oscillation data and the experimental
bounds on the decays , these LFV -decays are found to
be sizable, among which the largest-rate channel can
ocuur with a branching ratio of and may be accessible at the LHC or
GiagZ experiment.Comment: 8 pages,4 ps files, to appear in EPJ
J/ suppression at 200 GeV in the comovers interaction model
The yield of per binary nucleon-nucleon collision in and
collisions at GeV is computed in the framework of the
dual parton model, supplemented with final state interaction (comovers
interaction). For the latter we use the same value of the cross-section,
mb, which describes the anomalous suppression
observed at CERN-SPS energies. Several possibilities for the value of the
absorptive cross-section are considered. Shadowing is introduced in both the
comovers and the yields. A comparison with the results at CERN-SPS,
including a prediction for collisions, is also presented.Comment: 15 pages, 3 figure
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