  When a metal undergoes continuous quantum phase transition, the correlation
length diverges at the critical point and the quantum fluctuation of order
parameter behaves as a gapless bosonic mode. Generically, the coupling of this
boson to fermions induces a variety of unusual quantum critical phenomena, such
as non-Fermi liquid behavior and various emergent symmetries. Here, we perform
a renormalization group analysis of the semimetal-superconductor quantum
criticality in a three-dimensional anisotropic Weyl semimetal. Surprisingly,
distinct from previously studied quantum critical systems, the anomalous
dimension of anisotropic Weyl fermions flows to zero very quickly with
decreasing energy, and the quasiparticle residue takes a nonzero value. These
results indicate that, the quantum fluctuation of superconducting order
parameter is irrelevant at low energies, and a simple mean-field calculation
suffices to capture the essential physics of the superconducting transition. We
thus obtain a phase transition that exhibits trivial quantum criticality, which
is unique comparing to other invariably nontrivial quantum critical systems.
Our theoretical prediction can be experimentally verified by measuring the
fermion spectral function and specific heat.
