58 research outputs found
The interference between virtual photon and 1-- charmonium in e+e-experiment
e+e- Experiments producing charmonium are reviewed. It is found that the
contribution of the continuum amplitude via virtual photon was neglected in
almost all the experiments and the channels analyzed. It is shown that the
contribution of the continuum part may affect the final results significantly
in psi(2S) and psi(3770) decays, while the interference between continuum and
resonance amplitudes may even affect the J/psi decays as well as the psi(2S)
and psi(3770). This should be considered in analyzing the "rho-pi puzzle"
between J/psi and psi(2s) decays, and the difference between inclusive hadron
and DDbar cross sections in psi(3770) decays.Comment: 6 pages, 2 figure
Relative phase between strong and electromagnetic amplitudes in psi(2S) to 0- 0- decays
With the known branching ratios of psi(2S) to pi+pi- and psi(2S) to K+K-, the
branching ratio of psi(2S) to K0short K0long is calculated as a function of the
relative phase between the strong and the electromagnetic amplitudes of the
psi(2S) decays. The study shows that the branching ratio of psi(2S) to K0short
K0long is sensitive to the relative phase and a measurement of the K0short
K0long branching ratio will shed light on the relative phase determination in
psi(2S) to 0- 0- decays.Comment: 5 pages, 1 figur
Semi-inclusive B Decays and Direct CP Violation in QCD Factorization
We have systematically investigated the semi-inclusive B decays B->MX, which
are manifestations of the quark decay b->Mq, within the framework of
QCD-improved factorization. These decays are theoretically clean and have
distinctive experimental signatures. We focus on a class of these that do not
require any form factor information and therefore may be especially suitable
for extracting information on the angles and of the unitarity
triangle. The nonfactorizable effects, such as vertex-type and penguin-type
corrections to the two-body b decay and hard spectator corrections to the
3-body decay are calculable in the heavy quark limit. QCD factorization is
applicable when the emitted meson is a light meson or a charmonium. We discuss
the issue of the CPT constraint on partial rate asymmetries. The strong phase
coming from final-state rescattering due to hard gluon exchange between the
final states can induce large rate asymmetries for tree-dominated
color-suppressed modes . The nonfactorizable
hard spectator interactions in the 3-body decay, though phase-space suppressed,
are extremely important for the tree-dominated modes
, and the
penguin-dominated mode . In fact, they are dominated by the
hard spectator corrections. Our result for is in
agreement with experiment. The semi-inclusive decay modes: , ,
and are the most promising ones in searching for
direct CP violation. In fact, they have branching ratios of order
and CP rate asymmetries of order .Comment: 28 page
Influence of cigarette smoking on rate of reopening of the infarct-related coronary artery after myocardial infarction: A multivariate analysis
AbstractObjectives. This study sought to determine whether the reopening of the infarct-related vessel is related to clinical characteristics or cardiovascular risk factors, or both.Background. In acute myocardial infarction, thrombolytic therapy reduces mortality by restoring the patency of the infarct-related vessel. However, despite the use of thrombolytic agents, the infarct-related vessel remains occluded in up to 40% of patients.Methods. We studied 295 consecutive patients with an acute myocardial infarction who underwent coronary angiography within 15 days (mean [±SD] 6.7 ± 3.2 days) of the onset of symptoms. Infarct-related artery patency was defined by Thrombolysis in Myocardial Infarction trial flow grade ≥ 2. Four cardiovascular risk factors—smoking, hypertension, hypercholesterolemin and diabetes mellitus—and eight different variables—age, gender, in-hospital death, history of previous myocardial infarction, location of current myocardial infarction, use of thrombolytic agents, time interval between onset of symptoms, thrombolytic therapy and coronary angiography—were recorded in all patients.Results. Thrombolysis in current smokers and anterior infarct location on admission were the three independent factors highly correlated with the patency of the infarct-related vessel (odds ratios 3.2, 3.0 and 1.9, respectively). In smokers, thrombolytic therapy was associated with a higher reopening rate of the infarct vessel, from 35% to 77% (p < 0.001). Nonsmokers did not benefit from thrombolytic therapy, regardless of infarct location.Conclusions. These observational data, if replicated, suggest that in patients with acute myocardial infarction, thrombolytic therapy may be most effective in current smokers, whereas non-smokers and ex-smokers may require other management strategies, such as emergency percutaneous transluminal coronary angioplasty
Eta-eta' masses and mixing: a large N_c reappraisal
We reconcile the 1/N_c expansion with the observed eta-eta' mass spectrum.
The chiral corrections introduced for that purpose are natural and consistent
with the octet-singlet mixing angle theta=-(22\pm 1)^{\circ} extracted from
phenomenology in the large N_c limit.Comment: 9 pages, 1 figure. Version 2: three new equations added, reference
update
Ratio of Hadronic Decay Rates of J\psi and \psi(2S) and the \rho\pi Puzzle
The so-called \rho\pi puzzle of J\psi and \psi(2S) decays is examined using
the experimental data available to date. Two different approaches were taken to
estimate the ratio of J\psi and \psi(2S) hadronic decay rates. While one of the
estimates could not yield the exact ratio of \psi(2S) to J\psi inclusive
hadronic decay rates, the other, based on a computation of the inclusive ggg
decay rate for
\psi(2S) (J\psi) by subtracting other decay rates from the total decay rate,
differs by two standard deviations from the naive prediction of perturbative
QCD, even though its central value is nearly twice as large as what was naively
expected. A comparison between this ratio, upon making corrections for specific
exclusive two-body decay modes, and the corresponding experimental data
confirms the puzzles in
J\psi and \psi(2S) decays. We find from our analysis that the exclusively
reconstructed hadronic decays of the \psi(2S) account for only a small fraction
of its total decays, and a ratio exceeding the above estimate should be
expected to occur for a considerable number of the remaining decay channels. We
also show that the recent new results from the BES experiment provide crucial
tests of various theoretical models proposed to explain the puzzle.Comment: 8 pages, no figure, 4 table
Charmless hadronic decays and new physics effects in the general two-Higgs doublet models
Based on the low-energy effective Hamiltonian with the generalized
factorization, we calculate the new physics contributions to the branching
ratios of the two-body charmless hadronic decays of and mesons
induced by the new gluonic and electroweak charged-Higgs penguin diagrams in
the general two-Higgs doublet models (models I, II and III). Within the
considered parameter space, we find that: (a) the new physics effects from new
gluonic penguin diagrams strongly dominate over those from the new -
and - penguin diagrams; (b) in models I and II, new physics contributions
to most studied B meson decay channels are rather small in size: from -15% to
20%; (c) in model III, however, the new physics enhancements to the
penguin-dominated decay modes can be significant, , and
therefore are measurable in forthcoming high precision B experiments; (d) the
new physics enhancements to ratios {\cal B}(B \to K \etap) are significant in
model III, , and hence provide a simple and plausible new
physics interpretation for the observed unexpectedly large B \to K \etap
decay rates; (e) the theoretical predictions for and
in model III are still consistent with the data
within errors; (f) the significant new physics enhancements to the
branching ratios of and decays are helpful to improve the
agreement between the data and the theoretical predictions; (g) the theoretical
predictions of in the 2HDM's are generally
consistent with experimental measurements and upper limits ()Comment: 55 pages, Latex file, 17 PS and EPS figures. With minor corrections,
final version to be published in Phys.Rev. D. Repot-no: PKU-TH-2000-4
The use of tumour necrosis factor alpha-blockers in daily routine. An Austrian consensus project
To define relevant disease parameters and their respective limits indicating the initiation of TNF-α-blockers in individual patients. Subsequently, to analyze retrospectively patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) or ankylosing spondylitis (AS), who started TNF-α inhibition in 2006. Points to consider, regarded relevant for individual treatment decisions as well as their assessment methods, were ascertained by experts’ consensus applying the Delphi technique. Subsequently, these parameters’ thresholds with respect to the initiation of a TNF-α-blocker were identified. Thereafter, the rheumatologists representing 12 centres all over Austria agreed to retrospectively analyze their patients started on a TNF-α-blocker in 2006. Experts’ opinion regarding disease parameters relevant to initiate TNF-α-blockers in RA patients only slightly differed from those applied in clinical trials, but the parameters’ threshold values were considerably lower. For PsA patients, some differences and for AS patients, considerable differences between experts’ opinion and clinical studies appeared, which held also true for decisive parameters’ means and thresholds. Six hundred and fifty patients, started on TNF-blockers in 2006, could be analyzed retrospectively, 408 RA patients (53.3 years mean, 340 females), 93 PsA patients (48.9 years mean, 59 males) and 149 AS patients AS (42.2 years mean, 108 males), representing approximately 25% of all Austrian patients initiated on a TNF-blocker in this respective year. Far more individualized, patient-oriented treatment approaches, at least in part, are applied in daily routine compared with those derived from clinical trials or recommendations from investigative rheumatologists
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