  We present the first lattice-QCD calculation of the nucleon isovector
unpolarized parton distribution functions (PDFs) at the physical-continuum
limit using Large-Momentum Effective Theory (LaMET). The lattice results are
calculated using ensembles with multiple sea pion masses with the lightest one
around 135~MeV, 3 lattice spacings $a\in[0.06,0.12]$~fm, and multiple volumes
with $M_\pi L$ ranging 3.3 to 5.5. We perform a simultaneous chiral-continuum
extrapolation to obtain RI/MOM renormalized nucleon matrix elements with
various Wilson-link displacements in the continuum limit at physical pion mass.
Then, we apply one-loop perturbative matching to the quasi-PDFs to obtain the
lightcone PDFs. We find the lattice-spacing dependence to be much larger than
the dependence on pion mass and lattice volume for these LaMET matrix elements.
Our physical-continuum limit unpolarized isovector nucleon PDFs are found to be
consistent with global-PDF results.
