"Mathematical Physics"'s equivalent for Computer Science Mathematical Physics is a well defined scientific fields that deals with the application of mathematics , mathematical tools , and mathematical methods in the theories and the problems of physics.

Is there a well defined scientific field that deals with the application of mathematics , mathematical tools , and mathematical methods in the theories and the problems of computer science ?
When you use mathematics or mathematical models to understand physical nature around us and its dynamics, the mathematics in its association with physical laws become Physics. Similarly, when you leverage mathematics or its models like trees, graph, first-order logic etc to understand computational problems it becomes computer science.