  In this article we study the tail probability of the mass of critical
Gaussian multiplicative chaos (GMC) associated to a general class of
log-correlated Gaussian fields in any dimension, including the Gaussian free
field (GFF) in dimension two. More precisely, we derive a fully explicit
formula for the leading order asymptotics for the tail probability and
demonstrate a new universality phenomenon. Our analysis here shares similar
philosophy with the subcritical case but requires a different approach due to
complications in the analogous localisation step, and we also employ techniques
from recent studies of fusion estimates in GMC theory.
