385 research outputs found
A model for A=3 antinuclei production in proton-nucleus collisions
A simple coalescence model based on the same diagrammatic approach of
antimatter production in hadronic collisions as used previously for
antideuterons is used here for the hadroproduction of mass 3 antinuclei. It is
shown that the model is able to reproduce the existing experimental data on
Tbar and 3hebar production without any additional parameter.Comment: 7 figures. submitted to Eur. Phys. J.
Parameters of scalar resonances from the combined analysis of data on processes and decays
A combined analysis of data on isoscalar S-wave processes
and on decays
from the DM2, Mark III and BESIII
collaborations is performed to study mesons. The method of analysis is
based on analyticity and unitarity and uses an uniformization procedure. In the
analysis limited only to the multi-channel -scattering data, two
possible sets of parameters of the were found: in both cases the
mass was about 700 MeV but the total width was either about 600 or 930 MeV. The
extension of the analysis using only the DM2 and Mark III data on the
decays does not allow to choose between these sets. However, the data from
BESIII on the di-pion mass distribution in the decay
clearly prefers the wider state. Spectroscopic implications from
results of the analysis are also discussed.Comment: the formalism is also described (text overlap) in arXiv:1108.3725;
new extended analysis of data; revised PRD versio
Some indication for a missing chiral partner eta_4 around 2 GeV
The high-lying mesons in the light quark sector previously obtained from the
partial wave analysis of the proton-antiproton annihilation in flight at 1.9 -
2.4 GeV region at CERN reveal a very high degree of degeneracy. This degeneracy
can be explained as due to an effective restoration of both SU(2)_L * SU(2)_R
and U(1)_A symmetries combined with a principal quantum number n + J. In this
case there must be chiral partners for the highest spin states in the 2 and 2.3
GeV bands presently missing in the data. Here we reanalyze the Crystal Barrel
data and show an indication for existence of the missing state around
2 GeV. This result calls for further experimental search of the missing states
both in the proton-antiproton annihilation and in the production reactions.Comment: 4 pp. A fit with the energy-dependent width has been added that
agrees with the previous analysis. Accepted by PR
On nature of the scalar-isoscalar mesons in the uniformizing-variable method based on analyticity and unitarity
The experimental data on the processes
in the
channel have been jointly analyzed to study the status
and nature of the . The method of analysis is based on analyticity and
unitarity and uses an uniformization procedure. Some spectroscopic implications
from results of the analysis are discussed.Comment: 18 pages, 5 figures, 9 table
Masses and Internal Structure of Mesons in the String Quark Model
The relativistic quantum string quark model, proposed earlier, is applied to
all mesons, from pion to , lying on the leading Regge trajectories
(i.e., to the lowest radial excitations in terms of the potential quark
models). The model describes the meson mass spectrum, and comparison with
measured meson masses allows one to determine the parameters of the model:
current quark masses, universal string tension, and phenomenological constants
describing nonstring short-range interaction. The meson Regge trajectories are
in general nonlinear; practically linear are only trajectories for light-quark
mesons with non-zero lowest spins. The model predicts masses of many new
higher-spin mesons. A new meson is predicted with mass 1910 Mev. In
some cases the masses of new low-spin mesons are predicted by extrapolation of
the phenomenological short-range parameters in the quark masses. In this way
the model predicts the mass of to be MeV, and
the mass of to be MeV (the potential model predictions
are 100 Mev lower). The relativistic wave functions of the composite mesons
allow one to calculate the energy and spin structure of mesons. The average
quark-spin projections in polarized -meson are twice as small as the
nonrelativistic quark model predictions. The spin structure of reveals an
80% violation of the flavour SU(3). These results may be relevant to
understanding the ``spin crises'' for nucleons.Comment: 30 pages, REVTEX, 6 table
Study of the system in the mass range up to 1200 MeV
The reaction has been studied with GAMS-2000
spectrometer in the secondary 38 GeV/c -beam of the IHEP U-70
accelerator. Partial wave analysis of the reaction has been performed in the
mass range up to 1200 MeV. The -meson is seen as a sharp
peak in S-wave. The -dependence of production cross section has
been studied. Dominant production of the at a small transfer
momentum confirms the hypothesis of Achasov and Shestakov about significant
contribution of the exchange () in the mechanism
of meson production in -channel of the reaction.Comment: 4 pages, 3 figures, talk given at HADRON'9
Unquenching the scalar glueball
Computations in the quenched approximation on the lattice predict the
lightest glueball to be a scalar in the 1.5-1.8 GeV region. Here we calculate
the dynamical effect the coupling to two pseudoscalars has on the mass, width
and decay pattern of such a scalar glueball. These hadronic interactions allow
mixing with the scalar nonet, which is largely fixed by the
well-established K_0^*(1430). This non-perturbative mixing means that, if the
pure gluestate has a width to two pseudoscalar channels of ~100 MeV as
predicted on the lattice, the resulting hadron has a width to these channels of
only ~30 MeV with a large eta-eta component. Experimental results need to be
reanalyzed in the light of these predictions to decide if either the f_0(1500)
or an f_0(1710) coincides with this dressed glueball.Comment: 12 pages, LaTex, 3 Postscript figure
Search for Point Sources of High Energy Neutrinos with AMANDA
This paper describes the search for astronomical sources of high-energy
neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes,
used for the detection of Cherenkov light from upward traveling
neutrino-induced muons, buried deep in ice at the South Pole. The absolute
pointing accuracy and angular resolution were studied by using coincident
events between the AMANDA detector and two independent telescopes on the
surface, the GASP air Cherenkov telescope and the SPASE extensive air shower
array. Using data collected from April to October of 1997 (130.1 days of
livetime), a general survey of the northern hemisphere revealed no
statistically significant excess of events from any direction. The sensitivity
for a flux of muon neutrinos is based on the effective detection area for
through-going muons. Averaged over the Northern sky, the effective detection
area exceeds 10,000 m^2 for E_{mu} ~ 10 TeV. Neutrinos generated in the
atmosphere by cosmic ray interactions were used to verify the predicted
performance of the detector. For a source with a differential energy spectrum
proportional to E_{nu}^{-2} and declination larger than +40 degrees, we obtain
E^2(dN_{nu}/dE) <= 10^{-6}GeVcm^{-2}s^{-1} for an energy threshold of 10 GeV.Comment: 46 pages, 22 figures, 4 tables, submitted to Ap.
Hadroproduction and Polarization of Charmonium
In the limit of heavy quark mass, the production cross section and
polarization of quarkonia can be calculated in perturbative QCD. We study the
-averaged production of charmonium states in collisions at
fixed target energies. The data on the relative production rates of \jp and
is found to disagree with leading twist QCD. The polarization of the
\jp indicates that the discrepancy is not due to poorly known parton
distributions nor to the size of higher order effects (-factors). Rather,
the disagreement suggests important higher twist corrections, as has been
surmised earlier from the nuclear target -dependence of the production cross
section.Comment: 19 page
Results from the Antarctic Muon and Neutrino Detector Array (AMANDA)
We show new results from both the older and newer incarnations of AMANDA
(AMANDA-B10 and AMANDA-II, respectively). These results demonstrate that AMANDA
is a functioning, multipurpose detector with significant physics and
astrophysics reach. They include a new higher-statistics measurement of the
atmospheric muon neutrino flux and preliminary results from searches for a
variety of sources of ultrahigh energy neutrinos: generic point sources,
gamma-ray bursters and diffuse sources producing muons in the detector, and
diffuse sources producing electromagnetic or hadronic showers in or near the
detector.Comment: Invited talk at the XXth International Conference on Neutrino Physics
and Astrophysics (Neutrino 2002), Munich, Germany, May 25-30, 200
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