8,185 research outputs found

    Effective Lagrangian for Two-photon and Two-gluon Decays of PP-wave Heavy Quarkonium χc0,2\chi_{c0,2} and χb0,2\chi_{b0,2} states

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    In the traditional non-relativistic bound state calculation, the two-photon decay amplitudes of the PP-wave χc0,2\chi_{c0,2} and χb0,2\chi_{b0,2} 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 SS-wave ηc\eta_{c} and ηb\eta_{b} quarkonia, we show that the effective Lagrangian for the two-photon decays of the PP-wave χc0,2\chi_{c0,2} and χb0,2\chi_{b0,2} is given by the heavy quark energy-momentum tensor local operator or its trace, the QˉQ\bar{Q}Q scalar density and that the expression for χc0\chi_{c0} two-photon and two-gluon decay rate is given by the fχc0f_{\chi_{c0}} decay constant and is similar to that of ηc\eta_{c} which is given by fηcf_{\eta_{c}}. From the existing QCD sum rules value for fχc0f_{\chi_{c0}}, we get 5keV5\rm keV for the χc0\chi_{c0} 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

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    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

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    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

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    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 γγπ0\gamma\gamma^{*}\to \pi^{0} Transition Form Factor

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    The recent BaBar measurements of the γγπ0\gamma\gamma^{*}\to \pi^{0} transition form factor show spectacular deviation from perturbative QCD prediction for large space-like Q2Q^{2} up to 34GeV234\,\rm GeV^{2}. When plotted against Q2Q^{2}, Q2F(Q2)Q^{2}F(Q^{2}) shows steady increase with Q2Q^{2} in contrast with the flat Q2Q^{2} behavior predicted by perturbative QCD, and at 34GeV234\,\rm GeV^{2} 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 Z0π0γZ^{0}\to \pi^{0}\gamma, e+eπ0γe^{+}e^{-}\to \pi^{0}\gamma and apply our results to the γγπ0\gamma^{*}\gamma\to \pi^{0} transition form factor measured in the e+ee+eπ0e^{+}e^{-}\to e^{+}e^{-}\pi^{0} process with one highly virtual photon. We find that, the transition form factor F(Q2)F(Q^{2}) behaves as (m2Q2)×(ln(Q2/m2))2(\frac{m^{2}}{Q^{2}})\times (\ln(Q^{2}/m^{2}))^{2} and produces a striking agreement with the BaBar data for Q2F(Q2)Q^{2}F(Q^{2}) with m=132MeVm=132\,\rm MeV which also reproduces very well the CLEO data at lower Q2Q^{2}.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

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    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

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    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

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    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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