6,609 research outputs found
Scattering of vector mesons off nucleons
We construct a relativistic and unitary approach to 'high' energy pion- and
photon-nucleon reactions taking the , , ,
final states into account. Our scheme dynamically
generates the s- and d-wave nucleon resonances N(1535), N(1650) and N(1520) and
isobar resonances and in terms of quasi-local
interaction vertices. The description of photon-induced processes is based on a
generalized vector-meson dominance assumption which directly relates the
electromagnetic quasi-local 4-point interaction vertices to the corresponding
vertices involving the and fields. We obtain a satisfactory
description of the elastic and inelastic pion- and photon-nucleon scattering
data in the channels considered. The resulting s-wave - and
-nucleon scattering amplitudes are presented. Using these amplitudes we
compute the leading density modification of the and energy
distributions in nuclear matter. We find a repulsive energy shift for the
meson at small nuclear density but predict considerable strength in
resonance-hole like -meson modes. Compared to previous calculations our
result for the -meson spectral function shows a significantly smaller
in-medium effect. This reflects a fairly small coupling strength of the N(1520)
resonance to the channel.Comment: 78 pages, 19 figures, moderately revised version, accepted in Nucl.
Phys.
From meson- and photon-nucleon scattering to vector mesons in nuclear matter
We present a relativistic and unitary approach to pion- and photon-nucleon
scattering taking into account the , , , ,
, and channels. Our scheme dynamically
generates the s- and d-wave nucleon resonances N(1535), N(1650), N(1520) and
N(1700) and isobar resonances and in terms of
quasi-local two-body interaction terms. We obtain a fair description of the
experimental data relevant for slow vector-meson propagation in nuclear matter.
The s-wave - and -meson nucleon scattering amplitudes, which
define the leading density modification of the - and -meson
spectral functions in nuclear matter, are predicted.Comment: 6 pages, 1 figure; contribution to the Int. Workshop XXX on Gross
Properties of Nuclei and Nuclear Excitations: Ultrarelativistic Heavy Ion
Collisions, Hirschegg, Jan. 13-19, 200
Calculations of K+, K- and phi Production in Near-Threshold Proton-Nucleus Collisions
K+, K- and \phi meson production in proton-nucleus (pA) collisions has been
calculated within a BUU transport model. It is shown that the nucleon-hyperon
strangeness transfer channel is essential. The role of three-body reactions has
been investigated within the medium. The targetmass dependence of
production is predicted to give important information on the in-medium
properties of all three mesons.Comment: Talk presented by H.W.B. at the Budapest 2004 workshop on 'Hot and
Dense Matter in Relativistic Heavy Ion Collisions', March 24-27, 2004,
Budapest, Hungar
Discovery of the spectroscopic binary nature of the classical Cepheids FN Aql and V1344 Aql
We present the analysis of photometric and spectroscopic data of two
classical Cepheids, FN Aquilae and V1344 Aquilae. Based on the joint treatment
of the new and earlier radial velocity data, both Galactic Cepheids have been
found to be a member in a spectroscopic binary system.
To match the phases of the earlier radial velocity data correctly with the
new ones, we also determined the temporal behaviour of the pulsation period of
these Cepheids based on all available photometric data. The O-C graph covering
about half century shows slight changes in the pulsation period due to stellar
evolution for both Cepheids.Comment: 7 pages, 6 figures, 7 tables, accepted for publishing in the MNRA
Some functional equations related to the characterizations of information measures and their stability
The main purpose of this paper is to investigate the stability problem of
some functional equations that appear in the characterization problem of
information measures.Comment: 36 pages. arXiv admin note: text overlap with arXiv:1307.0657,
arXiv:1307.0631, arXiv:1307.0664, arXiv:1307.065
Medium-resolution echelle spectroscopy of pulsating variables and exoplanet host stars with sub-meter telescopes
Here we present two of our interesting results obtained over the last 18
months from spectroscopic monitoring of binary pulsating stars and exoplanet
host stars. Our investigations are very promising by demonstrating that modern
fiber-fed spectrographs open a whole new chapter in the life of small national
and university observatories.Comment: 3 pages, 3 figures. To be published in the proceedings of the
workshop on "Observing techniques, instrumentation and science for
metre-class telescopes", Sep. 2013, Tatranska Lomnica, Slovaki
Photometry of SN 2002bo with template image subtraction
VRI photometry of the type Ia supernova 2002bo is presented. This SN exploded
in a dusty region of the host galaxy NGC 3190, thus, subtraction of a template
frame was necessary to obtain reliable photometry. We used a template frame of
NGC 3190 taken during the course of our galaxy imaging project, fortunately,
just a few days before SN 2002bo was discovered. The aim of this project is to
collect template frames of nearby galaxies that are potential hosts of bright
SNe. Subtraction of pre-SN images helped us to exclude the background light
contamination of the host galaxy. The maximum occurred at JD 2452346, with
maximal V brightness of 13.58. MLCS analysis led to T0(B)=JD 2452346.1 pm 0.8
(fiducial B-maximum), E(B-V)=0.24 pm 0.02, mu0=32.46 pm 0.06, Delta=-0.14 pm
0.04. E(B-V)=0.24(2) indicates a significant extinction in the host galaxy as
the galactic reddening is negligible toward NGC 3190. The accepted value of
Delta indicates that SN 2002bo was a slightly overluminous SN by about 0.14
relative to fiducial SN Type Ia. The distance turned out to be 31.0 pm 3 Mpc.
In addition, the heavily obscured SN 2002cv was also detected on the I frame
taken on JD 2452434 (June 8, 2002), and a variable star is found in the field,
very close to the host galaxy.Comment: accepted by Astronomy and Astrophysic
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