Threshold Motion of Regge Poles

Abstract

The motion of Regge poles as $E\to 0$ is examined in detail. It follows from the well-known threshold law of the $S$ matrix that infinitely many poles approach $l=-\frac{1}{2}$, from the first and the third quadrants as $E\to 0+$, and from the second and third as $E\to 0-$. A possible way of including these poles in a representation of $S$ is indicated.