Gamma Rays from Small Scale Structures on Long Cosmic Strings

The formation of cusps on long cosmic strings is discussed and the probability of cusp formation is estimated. The energy distribution of the gamma-ray background due to cusp annihilation on long strings is calculated and compared to observations. Under optimistic assumptions about the cusp formation rate, we find that strings with a mass per unit length $\mu$ less than ${G\mu} = 10^{-14}$ will have an observable effect. However, it is shown that the gamma-ray bursters can not be attributed to long ordinary strings (or loops).