Sabine Jeschonnek

Quark hadron duality in a relativistic, confining model

Quark-hadron duality is an interesting and potentially very useful phenomenon, as it relates the properly averaged hadronic data to a perturbative QCD result in some kinematic regimes. While duality is well established experimentally, our current theoretical understanding is still incomplete. We employ a simple model to qualitatively reproduce all the features of Bloom-Gilman duality as seen in electron scattering. In particular, we address the role of relativity, give an explicit analytic proof of the equality of the hadronic and partonic scaling curves, and show how the transition from coherent to incoherent scattering takes place.

Faddeev and Glauber Calculations at Intermediate Energies in a Model for n+d Scattering

Obtaining cross sections for nuclear reactions at intermediate energies based on the Glauber formulation has a long tradition. Only recently the energy regime of a few hundred MeV has become accessible to ab initio Faddeev calculations of three-body scattering. In order to go to higher energies, the Faddeev equation for three-body scattering is formulated and directly solved without employing a partial wave decomposition. In the simplest form the Faddeev equation for interacting scalar particles is a three-dimensional integral equation in five variables, from which the total cross section, the cross sections for elastic scattering and breakup reactions, as well as differential cross sections are obtained. The same observables are calculated based on the Glauber formulation. The first order Glauber calculation and the Glauber rescattering corrections are compared in detail with the corresponding terms of the Faddeev multiple scattering series for projectile energies between 100 MeV and 2 GeV.

Modeling quark-hadron duality for relativistic, confined fermions

We discuss a model for the study of quark-hadron duality in inclusive electron scattering based on solving the Dirac equation numerically for a scalar confining linear potential and a vector color Coulomb potential. We qualitatively reproduce the features of quark-hadron duality for all potentials considered, and discuss similarities and differences to previous models that simplified the situation by treating either the quarks or all particles as scalars. We discuss the scaling results for PWIA and FSI, and the approach to scaling using the analog of the Callan-Gross relation for y-scaling.

Final state interaction effects in D (e, e-prime p) scattering

Abstract We present a systematic study of the final-state interation (FSI) effects in D(e, e p) scattering in the CEBAF energy range with particular emphasis on the phenomenon of the angular anisotropy of the missing momentum distribution. We find that FSI effects dominate at missing momentum p m ≳ 1.5 fm −1 . FSI effects in the excitation of the S -wave state are much stronger than in the excitation of the D -wave.

Scaling of Dirac fermions and the WKB approximation

We discuss a new method for obtaining the WKB approximation to the Dirac equation with a scalar potential and a timelike vector potential. We use the WKB solutions to investigate the scaling behavior of a confining model for quark-hadron duality. In this model, a light quark is bound to a heavy diquark by a linear scalar potential. Absorption of virtual photons promotes the quark to bound states. The analog of the parton model for this case is for a virtual photon to eject the bound, ground-state quark directly into free continuum states. We compare the scaling limits of the response functions for these two transitions.

The Science and Experimental Equipment for the 12 GeV Upgrade of CEBAF

This Conceptual Design Report (CDR) presents the compelling scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab to 12 GeV. Such a facility will make profound contributions to the study of hadronic matter.

A New calculation for D(e, e-prime p)n at GeV energies

W e perform a fully relativistic calculation ofthe D (e;e 0 p)n reaction in the im pulse approxim a- tion.W e em ploy theGrossequation to describethedeuteron ground state,and we usetheSAID param etrization ofthefullNN scattering am plitudeto describethenalstateinteractions(FSIs). W e include both on-shelland positive-energy o�-shellcontributions in our FSIcalculation. W e show resultsform om entum distributionsand angulardistributionsofthedierentialcrosssection, aswellasforvariousasym m etries.W e identify kinem atic regionswherevariouspartsofthenal stateinteractionsarerelevant,and discussthetheoreticaluncertaintiesconnected with calculations athigh m issing m om enta.

Quark-Hadron Duality

Quark-hadron duality and its potential applications are discussed. We focus on theoretical efforts to model duality.

Apparent Coulomb reacceleration of neutrons in electrodissociation of the deuteron

We demonstrate that the final state [ital p]-[ital n] interaction in the reaction of electrodissociation of the deuteron at large [ital Q][sup 2] in a static external field leads to the apparent reacceleration of neutrons. The shift of the neutron velocity from the velocity of the deuteron beam is related to the quantum-mechanical forward-backward asymmetry of the missing momentum distribution in the [sup 2]H ([ital e],[ital e][prime][ital p])[ital n] scattering.

Factorization breaking of AdT for polarized deuteron targets in a relativistic framework

We discuss the possible factorization of the tensor asymmetry