  We perform radiation-hydrodynamics simulations of binary neutron star mergers
in numerical relativity on the Japanese "K" supercomputer, taking into account
neutrino cooling and heating by an updated leakage-plus-transfer scheme for the
first time. Neutron stars are modeled by three modern finite-temperature
equations of state (EOS) developed by Hempel and his collaborators. We find
that the properties of the dynamical ejecta of the merger such as total mass,
average electron fraction, and thermal energy depend strongly on the EOS. Only
for a soft EOS (the so-called SFHo), the ejecta mass exceeds $0.01M_{\odot}$.
In this case, the distribution of the electron fraction of the ejecta becomes
broad due to the shock heating during the merger. These properties are
well-suited for the production of the solar-like $r$-process abundance. For the
other stiff EOS (DD2 and TM1), for which a long-lived massive neutron star is
formed after the merger, the ejecta mass is smaller than $0.01M_{\odot}$,
although broad electron-fraction distributions are achieved by the positron
capture and the neutrino heating.
