Measuring masses of semi-invisibly decaying particle pairs produced at hadron colliders

We introduce a variable useful for measuring masses of particles which are pair produced at hadron colliders, where each particle decays to one particle that is directly observable and another particle whose existence can only be inferred from missing transverse momentum. This variable is closely related to the transverse mass variable commonly used for measuring the W mass at hadron colliders, and like the transverse mass our variable extracts masses in a reasonably model independent way. Without considering either backgrounds or measurement errors we consider how our variable would perform measuring the mass of selectrons in a mSUGRA SUSY model at the LHC.