Polarization transfer observables for quasielastic proton-nucleus scattering in terms of a complete Lorentz invariant representation of theNNscattering matrix

Abstract

For the calculation of polarization transfer observables for quasielastic scattering of protons on nuclei, a formalism in the context of the Relativistic Plane Wave Impulse Approximation is developed, in which the interaction matrix is expanded in terms of a complete set of 44 independent invariant amplitudes. A boson-exchange model is used to predict the 39 amplitudes which were omitted in the formerly used five-term parameterization (the SP-VAT form) of the nucleon-nucleon scattering matrix. Use of the complete set of amplitudes eliminates the arbitrariness of the five-term representation. 24.10.Jv, 24.70.+s, Typeset using REVT E X where E 2 = p 2 + M 2 , and K n (n = 1 − 13) are kinematic covariants constructed from the Dirac matrices:K 9 = Q 22,µ (γ 5 ⊗ γ 5 γ µ ) K 10 = Q 12,µ (I 4 ⊗ γ µ )S K 11 = Q 21,µ (γ µ ⊗ I 4 )S K 12 = Q 12,µ (γ 5 ⊗ γ 5 γ µ )S K 13 = Q 21,µ (γ 5 γ µ ⊗ γ 5 )S

Momentum space analysis of distortion effects in quasielastic proton-nucleus scattering

“…2 of Ref [5]). This was the first reaction were the so-called 'quenching effect' in A u was observed which was hailed as a 'relativistic signature' [2].…”

“…Even though it is argued in Refs. [5] and [4] that it is preferable to use a general Lorentz invariant form of 1 ~ (the IA2 representation) in the calculation of quasielatic protonnucleus spin observables, we will now make use of the IA1 representation of _P. The reasons are the following: since this is the first relativistic distorted wave analysis of quasielastic proton-nucleus scattering it is advisable to use a simple representation of/~ which is consistent with parity and time-reversal invariance as well as charge symmetry.…”

Relativistic distorted-wave analysis of quasielastic proton-nucleus scattering

“…[1], Hillhouse et al studied various aspects of the model in a series of papers [2][3][4][5][6][7], namely, (i) more refined self-consistent calculations of the projectile and ejectile effective masses, (ii) sensitivities of the complete set of spin observables to different five-term parametrizations of the NN interaction, (iii) new meson-exchange parameters for the relativistic NN amplitudes, (iv) medium modifications of the NN interaction and the effect on ( p, p ) and ( p, n) complete sets of spin observables, and (v) the replacement of the ambiguous five-term parametrization ofF by a general Lorentz-invariant representation.…”

Quenching of the analyzing power for inclusive quasielastic (p→,p') scattering

“…An attractive feature of these models is the natural inclusion of density-dependent corrections to the NN interaction by replacing bare (or free) nucleon masses in the lower components of Dirac spinors with reduced effective nucleon masses m * within the context of the relativistic Walecka model [7]. However, despite a number of significant improvements [8,9] to the original relativistic plane wave model-related to the inclusion of improved effective nucleon masses [8], as well as the replacement of an ambiguous five term parametrization of the NN scattering matrix by a general Lorentz invariant representation (referred to as the IA2 representation) [9]-these models consistently fail to describe A y for inclusive ( p, p ) quasielastic scattering. Indeed this is not surprising, since plane wave models neglect the important effects of the distorting optical potentials on the scattering wave functions, which have been shown to be essential for describing exclusive ( p, 2p) analyzing powers [10].…”

“…1), employing only bare nucleon masses in the Dirac scattering spinors, the simplest SCDW model also overpredicts the data. For comparison, we also display the best currently available relativistic plane wave prediction [9], denoted by the dash-dash-dotted curve, based on the IA2 representation of the NN scattering amplitudes, and also employing effective nucleon masses which have been reduced by 20% relative to their bare values m 0 . The latter prediction is clearly inferior in comparison to the crudest SCDW calculation.…”