  We examine the macroscopic quantum tunneling (MQT) in high-Tc superconductor
Josephson junctions with a d-wave order parameter. Using microscopic
Hamiltonian and the functional integral method, we analytically obtain the MQT
rate (the inverse lifetime of the metastable state) for the c-axis twist
Josephson junctions. In the case of the zero twist angle, the system shows the
super-Ohmic dissipation due to the presence of the nodal quasiparticle
tunneling. Therefore, the MQT rate is strongly suppressed in compared with the
finite twist angle cases.
