Angular momentum constraints on dimuon energy asymmetries

Abstract

It is shown that if a dimuon system is produced with bounded angular momentum $j \le j_{max}$ then $\xi = \left|\frac{〈E_{-} - E_{+}〉}{〈E_{-} + E_{+}〉}\right|\le {\xi }_0$, where ${\xi }_0$ is the maximum zero of $P_{j_{max}+1}\left(\xi \right)$. No other assumptions regarding the source of the dimuons are made, and this bound can be reached. These bounds are considerably weaker than those of Pais and Treiman but are strong enough that they may be useful in future analyses. The results are applicable to a general two-body system and parity nonconservation is not required to reach the bound.