Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Is it possible to specify a latex package to load while pasting TeX expressions into Mathematica notebooks. For example I would like to load the braket package to typset something like \ket{\psi}
No, Mathematica has no (La)TeX interpreter. It either can or cannot translate a TeX expression—the concept of loading packages does not apply. If it cannot, you need to write a custom parser for it, and run that manually.