35 Result(s)

Article

Relationship Between the Proton Charge Form Factor and the Quark-Quark Interaction

We demonstrate how the parameterized proton elastic charge form factor may be used to determine the quark-quark interaction assuming a constituent-quark model of the nucleon and non-relativistic kinematics. T...

E.J.O. Gavin, R.M. Adam, H. Fiedeldey, S.A. Sofianos in Few-Body Systems (1995)

Article

Inclusion of Final-State-Interaction Effects at Higher Energies in the Photodisintegration of the α-Particle

Final-state-interaction (FSI) effects are included in the treatment of the photodisintegration of the α-particle via the K-matrix approximation. These are applied to the exact AGS-type integral equation for this...

H. Fiedeldey, S.A. Sofianos, G. Ellerkmann in Few-Body Systems (1995)

Chapter and Conference Paper

Photo-Induced Reactions on ⁴He

The photodisintegration of the α-particle and more specifically the ⁴He(γ,p)³H and the ⁴He(γ,n)³He reactions, have been at the center of theoretical as well as experimental studies since the early fifties. Variou...

S. A. Sofianos, H. Fiedeldey, G. Ellerkmann, W. Sandhas in Few-Body Problems in Physics ’93 (1994)

Chapter and Conference Paper

Nuclear Transitions in Muonic Molecules

A scheme, analogous to the Linear Combination of Atomic Orbitals (LCAO), is proposed to calculate rates of reactions of nucleon-group transfer between nuclei confined in muonic molecules. As an example the rat...

V. B. Belyaev, H. Fiedeldey, S. A. Rakityansky… in Few-Body Problems in Physics ’93 (1994)

Chapter and Conference Paper

Inversion at fixed-energy for nonlocal and algebraic potentials and N-body spectral inversion

H. Fiedeldey in Quantum Inversion Theory and Applications (1994)

Chapter and Conference Paper

Inversion at Fixed-Energy for Nonlocal and Algebraic Potentials and N-Body Spectral Inversion

If the local or nonlocal interaction between two particles or clusters is given we can calculate the complete set of phase shifts {δ(l, E)} for all values of the angular momentum l and energy E = ħ

H. Fiedeldey in Quantum Inversion Theory and Applications (1994)

Article

Quark-quark potentials from the inversion of baryon-spectra and its application to the Roper resonance

We show that it is in principle possible to determine the quark-quark potential, in the nonrelativistic potential model, from the baryon spectrum. The method we propose is based on the fact that the lowest ord...

H. Leeb, H. Fiedeldey, E. J. O. Gavin, S. A. Sofianos, R. Lipperheide in Few-Body Systems (1992)

Chapter and Conference Paper

The Integrodifferential Equation Approach and Some Applications

The Integrodifferential Equation Approach (IDEA) generalises the Faddeev equation from three to many-bodies, but retains its three-body like structure, due to the neglect of all N-particles correlations with ...

H. Fiedeldey in Few-Body Problems in Physics (1992)

Chapter and Conference Paper

Photodisintegration of ⁴He

The photodisintegration of ⁴He is calculated by employing recent integrodifferential equation techniques and an optical potential treatment of final state interaction. The results obtained reproduce the character...

S. A. Sofianos, H. Fiedeldey, W. Sandhas in Few-Body Problems in Physics (1992)

Chapter and Conference Paper

Inversion of Three-Quark Spectral Data

A method for the inversion of the spectrum of low-lying three-quark s-states within the hypercentral approximation is proposed. The procedure is a modification of the inverse spectrum method of Thacker, Quigg ...

H. Leeb, H. Fiedeldey, R. Lipperheide, W. A. Schnizer in Inverse Methods in Action (1990)

Chapter and Conference Paper

Phase Equivalence Between Nonlocal and Local Potentials Using Inversion and Supersymmetry

We briefly review recent work on the construction of phase equivalent local potentials to given nonlocal interactions of the Resonating Group Model type and the exact three-body Faddeev type. Direct, supersymm...

H. Fiedeldey, S. A. Sofianos, R. Lipperheide, H. Leeb in Inverse Methods in Action (1990)

Article

Several versions of the integro-differential equation approach to bound systems

We find that a single two-variable integro-differential equation, which includes all two-body correlations, produces results for three- and four-body bound systems in good agreement with those obtained with th...

M. Fabre de la Ripelle, H. Fiedeldey, S. A. Sofianos in Few-Body Systems (1989)

Article

Nonrelativistic potential model calculations for three-quark systems in the integro-differential equation approach

Employing a recently derived integro-differential equation which is equivalent to the Faddeev equation, in an adiabatic approximation, we obtain accurate lower bounds to the binding energy of three-quark syste...

J. P. McTavish, H. Fiedeldey, M. Fabre de la Ripelle… in Few-Body Systems (1988)

Chapter and Conference Paper

Hyperspherical Methods for Three-Quark Systems

The accuracy of the lowest order hyperspherical calculations for baryon spectra compared to Faddeev calculations and the importance of the Mixed Symmetry State for the nucleon is demonstrated. The excellent fi...

M. Fabre de la Ripelle, H. Fiedeldey… in Few-Body Problems in Particle, Nuclear, At… (1987)

Chapter and Conference Paper

Equivalent Local Potentials for Three-Body Scattering

The observables in three-body processes can be calculated exactly, e.g. by means of Faddeev or similar equations. As is well known, the latter may be reformulated as coupled multichannel equations of the Lippm...

E. O. Alt, H. Fiedeldey, S. A. Sofianos in Few-Body Problems in Particle, Nuclear, At… (1987)

Chapter and Conference Paper

An Integro-Differential Equation Approach to Few- and Many Body Systems

It is shown that a new two-variable integro-differential equation for an A-boson bound system which takes all two-body correlations exactly into account and is exact for A = 3 and S-state projected potentials,...

M. Fabre de la Ripelle, H. Fiedeldey… in Few-Body Problems in Particle, Nuclear, At… (1987)

Article

Equivalent local potential for the fish bone optical potential by inversion of its phase shifts

By inversion of the fish bone optical model phase shifts for α -¹⁶O scattering we confirm the presence of a Pauli barrier in the surface region of the corresponding equivalent local potential. In the interior the...

R. Lipperheide, H. Fiedeldey, E. W. Schmid… in Zeitschrift für Physik A Atoms and Nuclei (1985)

Chapter and Conference Paper

The equivalent local potential for the case of channel coupling by means of the inverse scattering method

As a simulation of the nuclear structure calculation of the optical model potential, a set of coupled equations was solved, in which all the potentials (diagonal and inter-channel ) were real. The resulting S-...

G. H. Rawitscher, H. Fiedeldey… in Medium Energy Nucleon and Antinucleon Scat… (1985)

Chapter and Conference Paper

Determination of nuclear optical potentials by inversion

An inversion method for the determination of nuclear optical potentials from scattering functions and elastic differential cross sections is discussed. The effect of experimental errors on the potentials is ta...

R. Lipperheide, H. Fiedeldey, H. Leeb in Advanced Methods in the Evaluation of Nucl… (1985)

Article

Nonlocal potentials and their exact and approximate local and velocity-dependent equivalents

We show that good approximations to the exact equivalent local potential (ELP) and dam** factor of a nonlocal Perey-Buck potential can be calculated in the partial wave WKB approximation of Horiuchi. The exa...

H. Fiedeldey, S. A. Sofianos in Zeitschrift für Physik A Atoms and Nuclei (1983)