A method for measurement of the top quark mass using the mean decay   length of b hadrons in ttbar events
  We present a new method for the experimental determination of the top quark mass that is based upon the mean distance of travel of b hadrons in top quark events. The dominant systematic uncertainties of this method are not correlated with those of other methods, but alarge number of events is required to achieve small statistical uncertainty. Large ttbar event samples are expected from Run II of the Fermilab Tevatron and the CERN Large Hadron Collider (LHC). We show that by the end of Run II, a single experiment at the Tevatron could achieve a top quark mass uncertainty of ~5 GeV/c^2 by this method alone. At the CERN LHC, this method could be comparable to all others methods, which are expected to achieve an uncertainty of ~1.5 GeV/c^2 per experiment. This new method would provide a useful cross-check to other methods, and could be combined with them to obtain a substantially reduced overall uncertainty. 
C. S. Hill, J. R. Incandela, J. M. Lamb