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Title:Numerical study of Regge cuts due to absorption in neutral pion photoproduction
Author(s):Miller, Robert Alan
Doctoral Committee Chair(s):Wyld, H.W.
Department / Program:Physics
Subject(s):numerical study
Regge cuts
neutral pion photoproduction
absorptive Regge models
Abstract:We examine in some detail the numerical features of some absorptive Regge models of neutral pion photoproduction. We start be reviewing the formalism in a consistent notation. The formalism contains derivations of the two expressions commonly used to calculate absorbed scattering amplitudes and their relation to Regge cut parametrizations. The physical picture behind the derivations is that absorbed Regge scattering is the result of secondary scattering of the products of the pure Regge exchange so that particles are scattered into inelastic channels. The scattering of the particles which remain in the channel of interest is taken to be elastic scattering as measured experimentally. The oldest of the two absorptive expressions is the Gottfried-Jackson partial wave form; the newer expression involves an integral over the intermediate scattering angle. The integral absorption expression is used for most of the calculations in this work. Unitarity and factorization are discussed briefly regarding their relation to the calculations presented. Numerical results are obtained by choosing a specific parametrization for the Regge exchange and performing the required numerical integrations. We present graphs of the discontinuities across the Regge cut which is generated, the contribution to the s- and t-channel scattering amplitudes due to the cut, and the fit to the data which is obtained. The s dependence of the absorptive corrections is discussed. We find that the straightforward absorptive Regge model does not fit the data well. For this reason we examine the effects produced by the modifications of the straightforward model which have been used in several published fits. We find that the omission of the nonsense wrong-signature zero has a beneficial effect. We argue that, independent of the presence or absence of a nonsense wrong-signature zero, the effects of the cut calculated in the manner presented are too small, and that an arbitrary multiplication of the cut amplitude bya factor of about 2 is necessary in the types of absorptive Regge fits which have been tried.
Issue Date:1970
Genre:Dissertation / Thesis
Rights Information:1970 Robert Alan Miller
Date Available in IDEALS:2011-07-26
Identifier in Online Catalog:2167330

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