Measurement of the Top Quark Mass with Dilepton Events Selected using Neuroevolution at CDF
Aaltonen et al. (including Shimon Whiteson)
We report a measurement of the top quark mass M_t in the dilepton decay channel t\bart\rightarrow b\ell'^+Ν'_\elløverlineb\ell^-øverlineΝ_\ell. Events are selected with a neural network which has been directly optimized for statistical precision in top quark mass using neuroevolution, a technique modeled on biological evolution. The top quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0 fb^-1 of p\barp collisions collected with the CDF II detector, yielding a measurement of M_t= 171.2± 2.7(\textrmstat.)± 2.9(\textrmsyst.)\mathrm GeV/c^2.