The discrete periodic Pitman transform: invariances, braid relations, and Burke properties

Abstract

We develop the theory of the discrete periodic Pitman transform, first introduced by Corwin, Gu, and the fifth author. We prove that the discrete periodic Pitman transform satisfies the same braid relations that are satisfied for the full-line Pitman transform shown by Biane, Bougerol, and O'Connell. This defines a group action of the infinite symmetric group on sequences of vectors in ${\mathbb{R}}^{{\mathbb{Z}}_N}$. We prove that, for polymers in a periodic environment, single-path and multi-path partition functions are preserved under the action of this transform on the weights in the polymer model. Combined with a new inhomogeneous Burke property for the periodic Pitman transform, we prove a multi-path invariance result for the periodic inverse-gamma polymer under permutations of the column parameters. In the limit to the full-line case, we obtain a multi-path extension of a recent invariance result of Bates, Emrah, Martin, Seppäläinen, and the fifth author, in both positive and zero-temperature.

v3, 19 pages, 5 figures. Adjusted the order of the inputs in the definition of the periodic Pitman transform to streamline the proofs. Switched the order of the first two main theorems, and we now give a self-contained proof of the involution of the periodic Pitman transform in Section 2.2