The purpose of this book is to introduce two recent topics in mathematical physics and probability theory: the Schramm–Loewner evolution (SLE) and interacting particle systems related to random matrix theory. A typical example of the latter systems is Dyson's Brownian motion (BM) model. The SLE and Dyson's BM model may be considered as "children" of the Bessel process with parameter *D*, BES(*D*), and the SLE and Dyson's BM model as "grandchildren" of BM. In Chap. 1 the parenthood of BM in diffusion processes is clarified and BES(*D*) is defined for any *D* ≥ 1. Dependence of the BES(*D*) path on its initial value is represented by the Bessel flow. In Chap. 2 SLE is introduced as a complexification of BES(*D*). Rich mathematics and physics involved in SLE are due to the nontrivial dependence of the Bessel flow on *D*. From a result for the Bessel flow, Cardy's formula in Carleson's form is derived for SLE. In Chap. 3 Dyson's BM model with parameter β is introduced as a multivariate extension of BES(*D*) with the relation *D* = β + 1. The book concentrates on the case where β = 2 and calls this case simply the Dyson model.

The Dyson model inherits the two aspects of BES(3); hence it has very strong solvability. That is, the process is proved to be determinantal in the sense that all spatio-temporal correlation functions are given by determinants, and all of them are controlled by a single function called the correlation kernel. From the determinantal structure of the Dyson model, the Tracy–Widom distribution is derived.