511 research outputs found
Dynamic Properties of Charmonium
Nonrelativistic quark models of charmonia are tested by comparison of
theoretical charmonium decay constants, form factors, and widths
with experiment and lattice gauge computations. The importance of relativistic
effects, a running coupling, and the correct implementation of bound state
effects are demonstrated. We describe how an improved model and computational
techniques resolve several outstanding issues in previous nonrelativistic quark
models such as the use of `correction' factors in quark model form factors,
artificial energy prescriptions in decay constant calculations, and ad hoc
phase space modifications. We comment on the small experimental value of
and the D-wave component of the . Decay constants and
widths for bottomonium are also presented.Comment: 22 pages, 22 ps figures (table entries corrected, text modified
Strange-Beauty Meson Production at Colliders
The production rates and transverse momentum distributions of the
strange-beauty mesons and at colliders are calculated
assuming fragmentation is the dominant process. Results are given for the
Tevatron in the large transverse momentum region, where fragmentation is
expected to be most important.Comment: Minor changes in the discussion section. Also available at
http://www.ph.utexas.edu/~cheung/paper.htm
On the and as Bound States and Approximate Nambu-Goldstone Bosons
We reconsider the two different facets of and mesons as
bound states and approximate Nambu-Goldstone bosons. We address several topics,
including masses, mass splittings between and and between and
, meson wavefunctions, charge radii, and the wavefunction overlap.Comment: 15 pages, late
Effect of integrated care for sick listed patients with chronic low back pain: economic evaluation alongside a randomised controlled trial
Objective To evaluate the cost effectiveness, cost utility, and cost-benefit of an integrated care programme compared with usual care for sick listed patients with chronic low back pain
Ratios of and Meson Decay Constants in Relativistic Quark Model
We calculate the ratios of and meson decay constants by applying the
variational method to the relativistic hamiltonian of the heavy meson. We adopt
the Gaussian and hydrogen-type trial wave functions, and use six different
potentials of the potential model. We obtain reliable results for the ratios,
which are similar for different trial wave functions and different potentials.
The obtained ratios show the deviation from the nonrelativistic scaling law,
and they are in a pretty good agreement with the results of the Lattice
calculations.Comment: 13 pages, 1 Postscript figur
The ACRA Anatomy Study (Assessment of Disability After Coronary Procedures Using Radial Access): A Comprehensive Anatomic and Functional Assessment of the Vasculature of the Hand and Relation to Outcome After Transradial Catheterization
BACKGROUND: The palmar arches serve as the most important conduits for digital blood supply, and incompleteness may lead to digital ischemia when the radial artery becomes obstructed after cardiac catheterization. The rate of palmar arch incompleteness and the clinical consequences after transradial access are currently unknown.METHODS AND RESULTS: The vascular anatomy of the hand was documented by angiography in 234 patients undergoing transradial cardiac catheterization. In all patients, a preprocedural modified Allen test and Barbeau test were performed. Upper-extremity function was assessed at baseline and 2-year follow-up by the QuickDASH. Incompleteness of the superficial palmar arch (SPA) was present in 46%, the deep palmar arch was complete in all patients. Modified Allen test and Barbeau test results were associated with incompleteness of the SPA (P=0.001 and P=0.001). The modified Allen test had a 33% sensitivity and 86% specificity for SPA incompleteness with a cutoff value of >10 seconds and a 59% sensitivity and 60% specificity with a cutoff value of >5 seconds. The Barbeau test had a 7% sensitivity and 98% specificity for type D and a 21% sensitivity and 93% specificity for types C and D combined. Upper-extremity dysfunction was not associated with SPA incompleteness (P=0.77).CONCLUSIONS: Although incompleteness of the SPA is common, digital blood supply is always preserved by a complete deep palmar arch. Preprocedural patency tests have thus no added benefit to prevent ischemic complications of the hand. Finally, incompleteness of the SPA is not associated with a loss of upper-extremity function after transradial catheterization
Di-electron and two-photon widths in charmonium
The vector and pseudoscalar decay constants are calculated in the framework
of the Field Correlator Method. Di-electron widths:
keV, keV,
keV, in good agreement with experiment, are obtained with the same coupling,
, in QCD radiative corrections. We show that the larger
is needed to reach agreement with experiment for
keV, keV, keV, and
also for keV,
keV. Meanwhile even larger gives rise to good description of
keV, keV, and
provides correct ratio of the branching fractions: Comment: 8 pages, no figure
The decay constants of pseudoscalar mesons in a relativistic quark model
The decay constants of pseudoscalar mesons are calculated in a relativistic
quark model which assumes that mesons are made of a valence quark antiquark
pair and of an effective vacuum like component. The results are given in terms
of quark masses and of some free parameters entering the expression of the
internal wave functions of the mesons. By using the pion and kaon decay
constants to fix the parameters of the
model one gets for the light quark masses
and the heavy quark masses in the
range: . In the case of
light neutral mesons one obtains with the same set of parameters
. The
values are in agreement with the experimental data and other theoretical
results.Comment: 11 pages, LaTe
Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic Quark Model
We investigate the and mesons in the relativistic quark model by
applying the variational method with the Gaussian wave function. We calculate
the Fermi momentum parameter , and obtain
GeV, which is almost independent of the input parameters, , ,
and . We then calculate the ratio /, and obtain the
result which is larger, by the factor of about 1.3, than
given by the naive nonrelativistic analogy. This result is in a good agreement
with the recent Lattice calculations. We also calculate the ratio
/. In these calculations the wave function at
origin is essential. We also determine by comparing the
theoretical prediction of the ACCMM model with the lepton energy spectrum of from the recent ARGUS analysis, and find that
GeV, when we use GeV. However, this
experimentally determined value of is strongly dependent on the value
of input parameter .Comment: 15 pages (Latex) (uses epsfig.sty, 1 figure appended as a uuencoded
compressed ps-file
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