8,185 research outputs found
Effective Lagrangian for Two-photon and Two-gluon Decays of -wave Heavy Quarkonium and states
In the traditional non-relativistic bound state calculation, the two-photon
decay amplitudes of the -wave and states depend
on the derivative of the wave function at the origin which can only be obtained
from potential models. However by neglecting the relative quark momenta, the
decay amplitude can be written as the matrix element of a local heavy quark
field operator which could be obtained from other processes or computed with
QCD sum rules technique or lattice simulation. Following the same line as in
recent work for the two-photon decays of the -wave and
quarkonia, we show that the effective Lagrangian for the two-photon decays of
the -wave and is given by the heavy quark
energy-momentum tensor local operator or its trace, the scalar
density and that the expression for two-photon and two-gluon decay
rate is given by the decay constant and is similar to that of
which is given by . From the existing QCD sum rules
value for , we get for the two-photon
width, somewhat larger than measurement, but possibly with large uncertainties.Comment: v3, LaTeX, 5 pages, 1 figure, minor typos corrected, to appear in
Physical Review
Relationship Between Obesity and Periodontal Status in Vietnamese Patients
This study aims to investigate periodontal status, and the relationship between obesity and periodontal status in patients who first visited the Institute of Traditional Medicine, Ho Chi Minh City, Vietnam. 118 patients aged 18 or older, including 56 obese subjects (BMI≥27.5, mean age: 33.8, males: 11, females: 45) and 62 non-obese subjects (BMI<27.5, mean age: 34.3, males: 4, females: 58) were enrolled for a period of 5 months from February 2014 to June 2014. The information on socio-demographic characteristics and dental habits were collected by questionnaire. Periodontal status (PLI, GI, BOP, PD, CAL) was examined and the anthropometric index was measured. There was significantly higher prevalence of periodontitis (39.3%) in the obese group than the non-obese group (16.4%). Means of GI, BOP, PD, and CAL in obese subjects were significantly higher than those in non-obese subjects. Significantly higher percentages of subjects who had lower education, visited dental offices, scaled and polished their teeth regularly were in the non-obese group than in the obese group. Multiple logistic regression analysis revealed that age (OR=3.10), routine of dental visit (OR=3.34) and obesity (OR=2.79) were risk factors significantly related to periodontitis. Periodontal status in obese subjects was poorer than non-obese subjects. Obesity might be the risk factor for periodontitis in Vietnamese patients
Charmless Final State Interaction in B-> pi pi decays
We estimate effects of the final state interactions in B -> pi pi decays
coming from rescattering of pi pi via exchange of rho, sigma, f_0 mesons. Then
we include the rho rho rescattering via exchange of pi, omega, a_1 mesons and
finally we consider contributions of the a_1 pi rescattering via exchange of
rho. The absorptive parts of amplitudes for these processes are determined. In
the case of pi^+ pi^- decay mode, due to model uncertainties, the calculated
contribution is |M_A| =< 1.7 x 10^-8 GeV. This produces a small relative strong
phase for the tree and color-suppressed B -> pi pi amplitudes consistent with
the result of a recent phenomenological analysis based on the BaBar and Belle
results for the B -> pi pi branching ratios and CP asymmetries.Comment: 10 pages, 2 figure
Two-photon decay of pseudoscalar quarkonia
We report on our recent evaluation of the two-photon width of the
pseudoscalar quarkonia, eta_c(nS) and eta_b(nS) in an approach based on
Heavy-Quark Spin Symmetry (HQSS). To what concerns the 1S state eta_c, our
parameter-free computation agrees with experiments, as well as most of other
theoretical works. On the other hand, our computation for the 2S-state looks 2S
like a confirmation that there may exist an anomaly related to the decay of
eta_c(2S), especially in the light of the new preliminary result of the Belle
collaboration. We also point out that the essentially model-independent ratio
of eta_b two-photon width to the Upsilon leptonic width and the eta_b
two-photon width could be used to extract the strong coupling constant alpha_s.Comment: Presented by T.N. Pham at the Joint Meeting
Heidelberg-Liege-Paris-Wroclaw (HLPW08), Spa, Belgium, 6-8 March 2008, 9
pages, 2 figures, LaTeX, uses aip-6s.clo, aipproc.cls and aipxfm.sty
(included
Chiral Anomaly Effects and the BaBar Measurements of the Transition Form Factor
The recent BaBar measurements of the transition
form factor show spectacular deviation from perturbative QCD prediction for
large space-like up to . When plotted against ,
shows steady increase with in contrast with the flat
behavior predicted by perturbative QCD, and at is
more than 50% larger than the QCD prediction. Stimulated by the BaBar
measurements, we revisit our previous paper on the cancellation of anomaly
effects in high energy processes , and apply our results to the
transition form factor measured in the
process with one highly virtual photon. We find that, the transition form
factor behaves as and produces a striking agreement with the BaBar data
for with which also reproduces very well the
CLEO data at lower .Comment: v4, LaTeX, 8 pages, one figure, minor changes(references), to appear
in Int. J. Mod. Phys.
Users guide Advanced Reactive Electronic Simulation (ARES) version 1.12
This Users Guide is for the Advanced Reactive Electronic Warfare Simulation (ARES) Version 1.12, created at the Naval Research Laboratory (NRL) under a project sponsored by the Office of Naval Research (ONR) titled Distributed and Networked C2W Technology (FY98-FYOO). The simulation is used to determine the optimum distributed C2W/EA configuration of assets including placement of sensors and system selection (jammer or receiver or both) for important mission scenarios leading to a better understanding of the minimum requirements for suppression of enemy air defense operations. ARES is a pulse level simulation that models the complex interaction of multiple radar systems being acted upon by multiple AEA aircraft, considering target aircraft radar cross section (RCS) and altitude, terrain masking effects, both standoff jamming and self protection jamming effects, and network connection effect. Its features include an object%-oriented scenario workbook allowing the users to build a battlefield scenario and a search procedure based on a genetic algorithm (GA) for optimizing configurations of what the core and peripheral components of the AEA architecture should be. ARES is available in two forms: Graphical User Interface (GUI) and parallel. ARES' GUI runs on a personal computer (PC) and its primary application is for setting up scenarios and post processing. ARES' parallel version runs over a cluster of Intel based Linux machines with Message- Passing Interface (MPI) and provides capability to execute multipleThis report was sponsored by the Applied Physics Laboratory, Johns Hopkins University
Mechanical failure of the Coonrad-Morrey linked total elbow arthroplasty: A case report
AbstractSemiconstrained (linked design) total elbow arthroplasty is indicated in a wide variety of cases. Long-term survival is better than with non-linked prostheses. However, mechanical failure of the hinge mechanism is a complication that may occur during follow-up. We report a case of failure of the axle assembly of a Coonrad-Morrey elbow prosthesis 8years after implantation for nonunion of a supracondylar distal humerus fracture. Initial revision surgery included changing the axle and the polyethylene bushings. Revision surgery was necessary 1year later when the axle failed again. A custom-designed locking axle had to be used to stabilize the hinge mechanism. After 3years follow-up, the hinge was intact, there was no loosening of the components and function of the elbow was good
Two-photon width of eta_c and eta'_c from Heavy-Quark Spin Symmetry
We evaluate the two-photon width of the pseudoscalar charmonia, Gamma(eta_c
-> gamma gamma) and Gamma(eta'_c -> gamma gamma), within a Heavy-Quark
Spin-Symmetry setting and show that whereas the former agrees with experiment,
the latter is more than twice larger than the recent measurement by CLEO. When
binding-energy effects are included in the eta'_c case, the discrepancy is
worse, pointing out at a possible anomaly in the eta'_c decay.Comment: 4 pages, 2 figures, Revtex4; v2: discussions enlarged and some
references added. The conclusions are unchange
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