Multi-fold Darboux transformations of the extended bigraded Toda hierarchy

TL;DR

This paper develops multi-fold Darboux transformations for the extended bigraded Toda hierarchy (EBTH), generating new solutions including solitons, and highlights differences from the extended Toda hierarchy, with potential applications in Gromov-Witten theory.

Contribution

It introduces two types of Darboux transformations for EBTH, providing explicit determinant representations and new solution generation methods.

Findings

Generated soliton solutions for (N,N)-EBTH.

Identified differences between EBTH and ETH flows.

Analyzed soliton velocities and flow behaviors.

Abstract

With the extended logarithmic flow equations and some extended Vertex operators in generalized Hirota bilinear equations, extended bigraded Toda hierarchy(EBTH) was proved to govern the Gromov-Witten theory of orbiford $c_{NM}$ in literature. The generating function of these Gromov-Witten invariants is one special solution of the EBTH. In this paper, the multi-fold Darboux transformations and their determinant representations of the EBTH are given with two different gauge transformation operators. The two Darboux transformations in different directions are used to generate new solutions from known solutions which include soliton solutions of $(N,N)$-EBTH, i.e. the EBTH when $N=M$. From the generation of new solutions, one can find the big difference between the EBTH and the extended Toda hierarchy(ETH). Meanwhile we plotted the soliton graphs of the $(N,N)$-EBTH from which some approximation analysis will be given. From the analysis on velocities of soliton solutions, the difference between the extended flows and other flows are shown. The two different Darboux transformations constructed by us might be useful in Gromov-Witten theory of orbiford $c_{NM}$.