P26
Gaussian Fluctuations in Models of Statistical Mechanics – Fine Asymptotics for the Magnetization
Description Phase 2
In our project we investigate several models stemming from statistical mechanics
including the Curie-Weiss model and variants thereof, e.g. with random
interactions. Famous results in these settings include the weak convergence
of the average spin, called the magnetization, and its Gaussian fluctuations
for high temperatures. However, it is a natural question to ask for
finer asymptotics including large deviation results and rates of convergence.
We like to apply the method of cumulants as well as Stein's method in order
to obtain fine asymptotics for the magnetization in these models.
For the classical Curie-Weiss model Berry-Esseen bounds were derived by
Stein's method and via mod-Gaussian convergence. Further asymptotics for
mixed moments are available. For Curie-Weiss models with random interactions
modeled by an Erdős-Rényi random graph also Berry-Esseen bounds
were derived by Stein's method both in the quenched and annealed setting.
For the vector of block magnetizations in the Block Spin Ising models, the
question of asymptotics beyond Gaussian fluctuations are open. However,
the asymptotic moments are known. Therefore the method of cumulants,
which has proven to be a useful tool for such fine asymptotics and gained interest
over the last years, can lead to further interesting results and provide
deeper insight into the behaviour of the magnetization.
Due to the long-range dependence in the Ising model, the method of cumulants
does yield Berry-Esseen bounds only in some temperature regimes. In
our interest in finer asymptotics, we are convinced that a generalization of
Stein's method to weighted dependency graphs will, on the one hand, allow
convergence rates for the missing regimes in the Ising model and, on the
other hand, extend the field of application of Stein's method by a substantial
class of dependent random variables.