Lax connections in TT-deformed integrable field theories

In this work,we attempt to construct the Lax connections of TT-deformed integrable field theories in two different ways.With reasonable assumptions,we make an ansatz and find the Lax pairs in the TT-deformed affine Toda theories and the principal chiral model by solving the Lax equations directly.This method is straightforward,but it may be difficult to apply for general models.We then make use of a dynamic coordinate transformation to read the Lax connection in the deformed theory from the undeformed one.We find that once the inverse of the transformation is available,the Lax connection can be read easily.We show the construction explicitly for a few classes of scalar models and find consistency with those determined using the first method.