587 research outputs found

    On the Lorentz structure of the confinement potential

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    We investigate the Lorentz structure of the confinement potential through a study of the meson spectrum using Salpeter's instantaneous approximation to the Bethe-Salpeter equation. The equivalence between Salpeter's and a random-phase-approximation (RPA) equation enables one to employ the same techniques developed by Thouless, in his study of nuclear collective excitations, to test the stability of the solutions. The stablity analysis reveals the existence of imaginary eigenvalues for a confining potential that transforms as a Lorentz scalar. Moreover, we argue that the instability persists even for very large values of the constituent quark mass. In contrast, we find no evidence of imaginary eigenvalues for a timelike vector potential --- even for very small values of the constituent mass.Comment: 18 pages using RevTeX 3.0, with 8 figures available upon request, FSU-SCRI-94-1

    The Anatomy of a Weight Recidivism and Revision Bariatric Surgical Clinic

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    Abstract. Weight recidivism in bariatric surgery failure is multifactorial. It ranges from inappropriate patient selection for primary surgery to technical/anatomic issues related to the original surgery. Most bariatric surgeons and centers focus on primary bariatric surgery while weight recidivism and its complications are very much secondary concerns. Methods. We report on our initial experience having established a dedicated weight recidivism and revisional bariatric surgery clinic. A single surgeon, dedicated nursing, dieticians, and psychologist developed care maps, goals of care, nonsurgical candidate rules, and discharge planning strategies. Results. A single year audit (2012) of clinical activity revealed 137 patients, with a mean age 49 ± 10.1 years (6 years older on average than in our primary clinic), 75% of whom were women with BMI 47 ± 11.5. Over three quarters had undergone a vertical band gastroplasty while 15% had had a laparoscopic adjustable gastric band. Only 27% of those attending clinic required further surgery. As for primary surgery, the role of the obesity expert clinical psychologist was a key component to achieving successful revision outcomes. Conclusion. With an exponential rise in obesity and a concomitant major increase in bariatric surgery, an inevitable increase in revisional surgery is becoming a reality. Anticipating this increase in activity, Alberta Health Services, Alberta, Canada, has established a unique and dedicated clinic whose early results are promising

    Property Valuation for Transfer Taxes: Art, Science, or Arbitrary Decision?

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    According to the regulations, the value referred to in the IRC is defined as fair market value. Fair market value is itself defined as the price at which the property would change hands between a willing buyer and a willing seller, neither being under any compulsion to buy nor sell, and both having reasonable knowledge of relevant facts. 9 The so-called hypothetical willing buyer/seller standard is prevalent throughout the case law dealing with this issue. 0 Given the importance of this standard, additional discussion is warranted. The standard requires an analysis of both sides of the transaction. It is not appropriate to focus solely upon what someone would pay for the property or for what price someone would sell it. Rather, one must look at both sides of the transaction. In the decisions discussed below, courts criticize both parties for having failed to look at the buyer\u27s and seller\u27s positions. Furthermore, the hypothetical buyer and seller are just that - hypothetical. One should not attempt to focus on a particular buyer or seller, such as family members or corporations. The hypothetical buyer and seller are also presumed to deal at arm\u27s length

    On the validity of the reduced Salpeter equation

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    We adapt a general method to solve both the full and reduced Salpeter equations and systematically explore the conditions under which these two equations give equivalent results in meson dynamics. The effects of constituent mass, angular momentum state, type of interaction, and the nature of confinement are all considered in an effort to clearly delineate the range of validity of the reduced Salpeter approximations. We find that for J̸=0J\not{\hspace*{-1.0mm}=}0 the solutions are strikingly similar for all constituent masses. For zero angular momentum states the full and reduced Salpeter equations give different results for small quark mass especially with a large additive constant coordinate space potential. We also show that 1m\frac{1}{m} corrections to heavy-light energy levels can be accurately computed with the reduced equation.Comment: Latex (uses epsf macro), 24 pages of text, 12 postscript figures included. Slightly revised version, to appear in Phys. Rev.

    A Bethe-Salpeter model for light mesons: spectra and decays

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    The spectra and electroweak decay properties of light mesons are analyzed within the framework of the instantaneous Bethe-Salpeter equation. The interaction kernel comprises alternative spin-structures for a parameterization of confinement and a residual quark-antiquark interaction based on instanton effects. It is shown that only with a vector confinement the parameters can be chosen such as to yield an excellent description of the light pseudoscalar and vector mesons including weak and two photon decays. However it is found that it is not possible to reconcile this with the Regge behavior of higher lying meson states with the same parameter set.Comment: 12 pages, RevTeX, TK-93-1

    Analysis of the instantaneous Bethe-Salpeter equation for qqˉq\bar{q}-bound-states

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    We investigate the structure of the instantaneous Bethe-Salpeter equation for qqˉq\bar{q}-bound states in the general case of unequal quark masses and develop a numerical scheme for the calculation of mass spectra and Bethe-Salpeter amplitudes. In order to appreciate the merits of the various competing models beyond the reproduction of the mass spectra we present explicit formulas to calculate electroweak decays. The results for an explicit quark model will be compared to experimental data in a subsequent paperComment: 11 pages, RevTeX, TK-93-1

    On the instantaneous Bethe-Salpeter equation

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    We present a systematic algebraic and numerical investigation of the instantaneous Bethe-Salpeter equation. Emphasis is placed on confining interaction kernels of the Lorentz scalar, time component vector, and full vector types. We explore stability of the solutions and Regge behavior for each of these interactions, and conclude that only time component vector confinement leads to normal Regge structure and stable solutions.Comment: Latex (uses epsf macro), 26 pages of text, 12 postscript figures included
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