Münster 2002 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 9: Poster Session: Theory

HK 9.4: Poster

Dienstag, 12. März 2002, 10:30–12:45, Foyer Chemie

Simple High Accuracy Calculations of the Three Nucleon System at Very Low Energies — •Harald W. Grießhammer — Institut für Theoretische Physik (T39), TU München, D-85747 Garching

At very low energies, pions do not have to be treated as explicit degrees of freedom in an Effective Field Theory of few nucleon systems. The resulting power counting allows for simple, model independent, systematic and rigorous computations of the properties of nuclear systems with an error estimate. Usually, high precision calculations are performed with relative ease. In the triton channel of the three nucleon system, it has however been demonstrated [1] that an unusual, non-perturbative renormalisation phenomenon leads to a three body force which is needed even at leading order in order to absorb cut-off dependence. This yields a limit cycle for the three body force, and explanations of the Efimov and Thomas effects as well as of the Phillips line of nuclear physics. Here, it is shown that this phenomenon is limited to the doublet S wave only, so that computations in the other channels can be performed with ease to high accuracy. Demonstrating a new technique to obtain results of increasing accuracy in the Effective Field Theory approach, corrections to the Phillips line obtained at LO as well as phase shifts in the triton channel of nd scattering are discussed both above and below the deuteron breakup point. The calculations converge rapidly.

Supported in part by DFG under grant GR 1887/1-2 and by BMBF.

[1.] P. Bedaque, H.-W. Hammer and U. van Kolck: Nucl. Phys. A676, 357 (2000).