Bisection-based asymmetric MT2 computation: a higher precision   calculator than existing symmetric methods
  An MT2 calculation algorithm is described. It is shown to achieve better precision than the fastest and most popular existing bisection-based methods. Most importantly, it is also the first algorithm to be able to reliably calculate asymmetric MT2 to machine-precision, at speeds comparable to the fastest commonly used symmetric calculators. 
Christopher G. Lester and Benjamin Nachman
hep-ph