  Through variational Monte Carlo calculation on Gutzwiller projected wave
functions, we study the quasiparticle(qp) weight for adding and removing an
electron from a high temperature superconductor. We find the qp weight is
particle-hole symmetric at sufficiently low energy. We propose to use the
tunneling asymmetry as a tool to study the mechanism of electron incoherence in
high temperature superconductors.
