Infinite critical boson induced non-Fermi liquid in $d=3-\epsilon$ dimensions

We study the fermion-boson coupled system in $d=3-\epsilon$ space dimensions near the quantum phase transition; infinite many boson modes located on a sphere become critical simultaneously, which is dubbed "critical boson sphere" (CBS). The fermions on the Fermi surface can be scattered to nearby points located on a boson ring in the low-energy limit. The number of boson scattering channel $N_{B}$ is also infinite, which renders the well-known Landau damping effect largely suppressed. The one-loop renormalization group analysis is performed with asymptotic $\epsilon$-expansion. We find that the fermion self-energy and Yukawa interaction vertex are dressed with $\epsilon$ poles; in addition, there emerges an enhancement due to the curvature effect of CBS. In certain perturbative regimes, we identify a marginal non-Fermi liquid (NFL) fixed point that exists intrinsically in the large-$N_B$ limit. The infinite critical bosons comprise a physical realization of the flavor degrees of freedom which has been proposed for matrix large-$N_B$ bosons.