265 research outputs found
On the Particle Data Group evaluation of Psi' and chi_c Branching Ratios
I propose a new evaluation of and branching ratios
which avoids the correlations affecting the current Particle Data Group
evaluation.
These correlations explain the apparent technique-dependent discrepancies
between the available determinations of the
and under the hypotesis that the current
values of the branching ratios are
overestimated.
In the process I also noticed that Particle Data Group has not restated many
of the older measurements, when necessary, for the new value of , which significantly affects the evaluation of some
relevant and exclusive branching ratios.Comment: 13 pages. Revised version. Submitted to Phys. Rev.
Electromagnetic form factors in the J/\psi mass region: The case in favor of additional resonances
Using the results of our recent analysis of e^+e^- annihilation, we plot the
curves for the diagonal and transition form factors of light hadrons in the
time-like region up to the production threshold of an open charm quantum
number. The comparison with existing data on the decays of J/\psi into such
hadrons shows that some new resonance structures may be present in the mass
range between 2 GeVand the J/\psi mass. Searching them may help in a better
understanding of the mass spectrum in both the simple and a more sophisticated
quark models, and in revealing the details of the three-gluon mechanism of the
OZI rule breaking in K\bar K channel.Comment: Formulas are added, typo is corrected, the text is rearranged.
Replaced to match the version accepted in Phys Rev
Possible large phase in psi(2S) -> 1-0- Decays
The strong and the electromagnetic amplitudes are analyzed on the basis of
the measurements of J/psi, psi(2S) -> 1-0- in e+e- experiments. The currently
available experimental information is revised with inclusion of the
contribution from e+e- -> gamma * -> 1-0- . The study shows that a large phase
around minus 90 degree between the strong and the electromagnetic amplitudes
could not be ruled out by the experimental data for psi(2S).Comment: 4 page
A Monte Carlo Study of the Dynamical-Flucautation Property of the Hadronic System Inside Jets
A study of the dynamical fluctuation property of jets is carried out using
Monte Carlo method. The results suggest that, unlike the average properties of
the hadronic system inside jets, the anisotropy of dynamical fluctuations in
these systems changes abruptly with the variation of the cut parameter \yct.
A transition point exists, where the dynamical fluctuations in the hadronic
system inside jet behave like those in soft hadronic collisions, i.e. being
circular in the transverse plan with repect to dynamical fluctuations. This
finding obtained from Jetset and Herwig Monte Carlo is encouraged to be checked
by experiments.Comment: 8 pages, 3 figure
Quark-hadron-duality in the charmonium and upsilon system
In this work we discuss the practical and conceptual issues related to
quark-hadron-duality in heavy-heavy systems. Recent measurements in the
charmonium region allow a direct test of quark-hadron-duality. We present a
formula for non-resonant background production in e^+ e^- \to D{\bar D} and
extract the resonance parameters of the \psi(3S)-\psi(6S). The obtained results
are used to investigate the upsilon energy range.Comment: 21 pages, 3 figures, references adde
An SU(3) model for octet baryon and meson fragmentation
The production of the octet of baryons and mesons in e^+ e^- collisions is
analysed, based on considerations of SU(3) symmetry and a simple model for
SU(3) symmetry breaking in fragmentation functions. All fragmentation
functions, D_q^h(x, Q^2), describing the fragmentation of quarks into a member
of the baryon octet (and similarly for fragmentation into members of the meson
octet) are expressed in terms of three SU(3) symmetric functions, \alpha(x,
Q^2), \beta(x, Q^2), and \gamma(x, Q^2). With the introduction of an SU(3)
breaking parameter, \lambda, the model is successful in describing
hadroproduction data at the Z pole. The fragmentation functions are then
evolved using leading order evolution equations and good fits to currently
available data at 34 GeV and at 161 GeV are obtained.Comment: 24 pages LaTeX file including 11 postscript figure file
Clocking hadronization in relativistic heavy ion collisions with balance functions
A novel state of matter has been hypothesized to exist during the early stage
of relativistic heavy ion collisions, with normal hadrons not appearing until
several fm/c after the start of the reaction. To test this hypothesis,
correlations between charges and their associated anticharges are evaluated
with the use of balance functions. It is shown that late-stage hadronization is
characterized by tightly correlated charge/anticharge pairs when measured as a
function of relative rapidity.Comment: 5 pages, 3 figure
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