Number-ratio fluctuations in high-energy particle production

In this article we will discuss the previously proposed quantity nu(dyn) [ C. Pruneau, S. Gavin, and S. Voloshin, Phys.Rev.C 66, 044904 (2002)], as a measure of the number-ratio fluctuations in high-energy particle production. We will show that nu(dyn) has pleasing mathematical properties making it ideal for the purpose. We will demonstrate its relation to two-particle correlations and how this measure can be generalized to higher-order correlations.