  We study the superconducting pairing correlations in the ground state of the
doped Hubbard model -- in its original form without hopping beyond nearest
neighbor or other perturbing parameters -- in two dimensions at intermediate to
strong coupling and near optimal doping. The nature of such correlations has
been a central question ever since the discovery of cuprate high-temperature
superconductors. Despite unprecedented effort and tremendous progress in
understanding the properties of this fundamental model, a definitive answer to
whether the ground state is superconducting in the parameter regime most
relevant to cuprates has proved exceedingly difficult to establish. In this
work, we employ two complementary, state-of-the-art many-body computational
methods, constrained path (CP) auxiliary-field quantum Monte Carlo (AFQMC) and
density matrix renormalization group (DMRG) methods, deploying the most recent
algorithmic advances in each. Systematic and detailed comparisons between the
two methods are performed. The DMRG is extremely reliable on small width
cylinders, where we use it to validate the AFQMC. The AFQMC is then used to
study wide systems as well as fully periodic systems, to establish that we have
reached the thermodynamic limit. The ground state is found to be
non-superconducting in the moderate to strong coupling regime in the vicinity
of optimal hole doping.
