  We present three measurements of the top quark mass in the lepton plus jets
channel with 1.9 fb-1 of data using quantities with minimal dependence on the
jet energy scale in the lepton plus jets channel at CDF. One measurement uses
the mean transverse decay length of b-tagged jets (L2d) to determine the top
mass, another uses the transverse momentum of the lepton (LepPt) to determine
the top mass, and a third measurement uses both variables simultaneously.
  Using the L2d variable we measure a top mass of 176.7 (+10.0) (-8.9) (stat)
+/- 3.4 (syst) GeV/c^2, using the LepPt variable we measure a top mass of 173.5
(+8.9) (-9.1) (stat) +/- 4.2 (syst) GeV/c^2, and doing the combined measurement
using both variables we arrive at a top mass result of 175.3 +/- 6.2 (stat) +/-
3.0 (syst) GeV/c^2. Since some of the systematic uncertainties are
statistically limited, these results are expected to improve significantly if
more data is added at the Tevatron in the future, or if the measurement is done
at the LHC.
