  We present measurements of the top quark mass in ttbar candidate events with
two final state leptons using 1 inverse fb of data collected by the D0
experiment. Our data sample is selected by requiring two fully identified
leptons or by relaxing one lepton requirement to an isolated track if at least
one jet is tagged as a b jet. The top quark mass is extracted after
reconstructing the event kinematics under the ttbar hypothesis using two
methods. In the first method, we integrate over expected neutrino rapidity
distributions, and in the second we calculate a weight for the possible top
quark masses based on the observed particle momenta and the known parton
distribution functions. We analyze 83 candidate events in data and obtain m_t =
176.2 +/- 4.8 (stat) +/- 2.1 (sys) GeV and m_t = 173.2 +/- 4.9 (stat) +/- 2.0
(sys) GeV for the two methods, respectively. Accounting for correlations
between the two methods, we combine the measurements to obtain m_t = 174.7 +/-
4.4 (stat) +/- 2.0 (sys) GeV.
