A discrete and coherent basis of intertwiners

Abstract

We construct a new discrete basis of 4-valent SU(2) intertwiners. This basis\npossesses both the advantage of being discrete, while at the same time\nrepresenting accurately the classical degrees of freedom; hence it is coherent.\nThe closed spin network amplitude obtained from these intertwiners depends on\ntwenty spins and can be evaluated by a generalization of the Racah formula for\nan arbitrary graph. The asymptotic limit of these amplitudes is found. We give,\nfor the first time, the asymptotics of 15j symbols in the real basis.\nRemarkably it gives a generalization of the Regge action to twisted geometries.\n