We study the tail exponents for the height function of the stationary stochastic
six-vertex model in the moderate deviations regime. For the upper tail of the height
function we find upper and lower bounds of matching order, with a tail exponent of
,
characteristic of KPZ distributions. We also obtain an upper bound for the lower tail
of the same order.
Our results for the stochastic six-vertex model hold under a restriction on the
model parameters for which a certain “microscopic concavity” condition
holds. Nevertheless, our estimates are sufficiently strong to pass through the
degeneration of the stochastic six-vertex model to the ASEP. We therefore obtain
tail estimates for both the current as well as the location of a second-class
particle in the ASEP with stationary (Bernoulli) initial data. Our estimates
complement the variance bounds obtained in the seminal work of Balázs and
Seppäläinen.
Keywords
KPZ universality, moderate deviations, six-vertex model