jost function description of elastic and few

JOST FUNCTION DESCRIPTION
OF ELASTIC AND FEW-BODY RESONANCES
R. O. Barrachina1*, F. Sánchez Plastic1 and P. A. Macri2
1
2
Centro Atómico Bariloche and Instituto Balseiro‡, 8400 S. C. de Bariloche, Argentina
Instituto de Astronomía y Física del Espacio, CC 67, Suc 28, 1428 Buenos Aires, Argentina
We discuss how the analysis of the zeros of the functions introduced by Res Jost in 1947 [1],
acting individually or collectively, provides a comprehensive framework for describing
resonances in single and multichannel collisions. In particular, we propose a generalization of
Wigner threshold law [2] that copes with some deviations recently observed in opening
reaction channels [3]. We also pay special attention to the appearance of zeros of the s-wave
Jost function in the fourth quadrant of the complex momentum plane, as analysed by
Nussenzveig in 1959 [4] but erroneously ruled out in following studies [5]. Finally, we
discuss the possible experimental observation of these and others effects.
References
[1]
[2]
[3]
[4]
[5]
*
‡
R. Jost, Helv. Phys. Acta 20 (1947) 256.
E. P. Wigner, Phys. Rev. 73 (1948) 1002.
R. O. Barrachina and P. Macri, Few-Body Systems 34 (2004) 175.
H. M. Nussenzveig, Nucl. Phys. 11 (1959) 499.
J. R. Taylor, Scattering Theory: The Quantum Theory of Nonrelativistic Collisions
(Wiley, New York, 1972).
[email protected]
Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, Argentina.