Determining the squark mass at the LHC

We propose a new way to determine the squark mass based on the shape of dijet invariant mass distribution of supersymmetry dijet events at the Large Hadron Collider. Our algorithm, which is based on event kinematics, requires that the branching ratio B(q-tilde→qZ-tilde1) is substantial for at least some types of squarks, and that mZ-tilde12/mq-tilde2<<1. We select dijet events with no isolated leptons, and impose cuts on the total jet transverse energy, ETtot=ET(j1)+ET(j2), on α=ET(j2)/mjj, and on the azimuthal angle between the two jets to reduce standard model backgrounds. The shape of the resulting dijet mass distribution depends sensitively on the squark mass, especially if the integrated luminosity is sufficient to allow a hard enough cut on ETtot and yet leave a large enough signal to obtain the mjj distribution. We simulate the signal and standard model backgrounds for 100 fb-1 integrated luminosity at 14 TeV requiring ETtot>700 GeV. We show that it should be possible to extract mq-tilde to within about 3% at 95% confidence level-similar to the precision obtained using mT2-from the dijet mass distribution if mq-tilde∼650 GeV, or to within ∼5% if mq-tilde∼1 TeV.