Sinusoidal Regge Oscillations from Short Lived Resonances*

It is well known that a resonance with a large angular life can produce sharp Breit-Wigner peaks in the energy dependence of integral cross sections [1,2]. Here we show that a short-lived resonance whose angular life is of order of one full rotation may produce a different kind of contribution to the integral cross section. This contribution has a sinousoidal form and its frequency is determined by the rotational constant of the complex. As one of the examples, we analyze the Regge oscillations observed in numerical simulations of the $F+H_2(v=0,j=0,\Omega =0) \rightarrow FH(v'=2,j'=0,\Omega'=0) + H$ reaction. In particular, we show that these oscillations are produced by two overlapping resonances located near the transition state and the van der Waals well, respectively [3]. \newline \newline [1] J. H. Macek, {\it et al.}, Phys. Rev. Lett., {\bf 93}, 183202, (2004). \newline [2] Z. Felfli {\it et al.}, J. Phys. B {\bf 39}, L353 (2006) \newline [3] D. Sokolovski, D. De Fazio, S. Cavalli and V. Aquilanti, J. Chem. Phys. (2007) (submitted).