is category theory being used in physics if yes in which branch in physics?
thanks in advance.
Yes category theory is used in quantum physics including the latest effort in post string theory.
Here's a link to John Baez's explanation of how category theory relates to basic quantum mechanics. http://www.math.ucr.edu/home/baez/categories.html
Take for example the quantization problem of Drinfel'd and Hopf structures. They are developed in a formal categorical sense.
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