Crossed-Boson-Exchange Contribution and Bethe-Salpeter Equation
Abstract
The contribution to the binding energy of a two-body system due to the crossed two-boson exchange contribution is calculated, using the Bethe-Salpeter equation. This is done for distinguishable, scalar particles interacting via the exchange of scalar massive bosons. The sensitivity of the results to the off-shell behaviour of the operator accounting for this contribution is discussed. Large corrections to the Bethe-Salpeter results in the ladder approximation are found. For neutral scalar bosons, the mass obtained for the two-body system is close to what has been calculated with various forms of the instantaneous approximation, including the standard non-relativistic approach. The specific character of this result is demonstrated by a calculation involving charged bosons, which evidences a quite different pattern. Our results explain for some part those obtained by Nieuwenhuis and Tjon on a different basis. Some differencies appear with increasing coupling constants, suggesting the existence of sizeable contributions involving more than two-boson exchanges.
- Publication:
-
Few-Body Systems
- Pub Date:
- April 2001
- DOI:
- 10.1007/s006010170014
- Bibcode:
- 2001FBS....30....5T
- Keywords:
-
- Specific Character;
- Massive Boson;
- Exchange Contribution;
- Scalar Particle;
- Operator Accounting