74,881 research outputs found
Meson-baryon threshold effects in the light-quark baryon spectrum
We argue that selected wave meson-baryon channels may play a key role to
match poor baryon mass predictions from quark models with data. The
identification of these channels with effective inelastic channels in data
analysis allows to derive a prescription which could improve the extraction and
identification of baryon resonances.Comment: 17 pages, 3 figures. Accepted for publication in Phys. Rev.
How to excite the internal modes of sine-Gordon solitons
We investigate the dynamics of the sine-Gordon solitons perturbed by
spatiotemporal external forces. We prove the existence of internal (shape)
modes of sine-Gordon solitons when they are in the presence of inhomogeneous
space-dependent external forces, provided some conditions (for these forces)
hold. Additional periodic time-dependent forces can sustain oscillations of the
soliton width. We show that, in some cases, the internal mode even can become
unstable, causing the soliton to decay in an antisoliton and two solitons. In
general, in the presence of spatiotemporal forces the soliton behaves as a
deformable (non-rigid) object. A soliton moving in an array of inhomogeneities
can also present sustained oscillations of its width. There are very important
phenomena (like the soliton-antisoliton collisions) where the existence of
internal modes plays a crucial role. We show that, under some conditions, the
dynamics of the soliton shape modes can be chaotic. A short report of some of
our results has been published in [J. A. Gonzalez et al., Phys. Rev. E, 65
(2002) 065601(R)].Comment: 14 .eps figures.To appear in Chaos, Solitons and Fractal
XMM-Newton and Deep Optical Observations of the OTELO fields: the Groth-Westphal Strip
OTELO (OSIRIS Tunable Emission Line Object Survey) will be carried out with
the OSIRIS instrument at the 10 m GTC telescope at La Palma, and is aimed to be
the deepest and richest survey of emission line objects to date. The deep
narrow-band optical data from OSIRIS will be complemented by means of
additional observations that include: (i) an exploratory broad-band survey that
is already being carried out in the optical domain, (ii) FIR and sub-mm
observations to be carried with the Herschel space telescope and the GTM, and
(iii) deep X-Ray observations from XMM-Newton and Chandra.Here we present a
preliminary analysis of public EPIC data of one of the OTELO targets,the
Groth-Westphal strip, gathered from the XMM-Newton Science Archive (XSA). EPIC
images are combined with optical BVRI data from our broadband survey carried
out with the 4.2m WHT at La Palma. Distance-independent diagnostics (involving
X/O ratio, hardness ratios, B/T ratio) are tested.Comment: 2 pages, 2 figures, uses graphicx package. To appear in proceedings
of "The X-Ray Universe 2005", San Lorenzo del Escorial, Spain, September
26-30, 200
Few-anyon systems in a parabolic dot
The energy levels of two and three anyons in a two-dimensional parabolic
quantum dot and a perpendicular magnetic field are computed as power series in
1/|J|, where J is the angular momentum. The particles interact repulsively
through a coulombic (1/r) potential. In the two-anyon problem, the reached
accuracy is better than one part in 10^5. For three anyons, we study the
combined effects of anyon statistics and coulomb repulsion in the ``linear''
anyonic states.Comment: LaTeX, 6 pages, 4 postscript figure
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