Graduate Student Struggles to Keep Up in Quantum Field Theory

[spacelike]

I just entered graduate school. As an undergraduate I took a graduate course in Quantum Mechanics, mostly for fun and practice because I knew the credits wouldn't transfer to the uni I was applying to for grad school.

So, I got accepted there and even though the credit wasn't transferred the advisor heard I was interested in theory and recommended that I take Quantum Field Theory anyway and try to test out of QM.
So that's what I signed up for.

We had 4 classes so far and I understand most of it, but it's all so new to me and the speed of the class makes it seem like this should be second nature by now.

They are talking about manifolds, covariant derivatives, groups, symmetries, etc.. like if it's something I should only be reviewing at this point rather than learning.
Feels like I'm fighting to just keep up, and if I'm right that this is just mostly review for a lot of the students in ther I'm sure it's going to get much much worse.I think I needed to take a class on group theory, or differential geometry first...
(I've taken neither)
should I study those? While I would love to read a textbook with a formal introduction to it, the material is already taking up enough of my time as it is, so are there any quick and dirty ways to get the information I need for this class? Maybe an online resource or something?

Thanks.

 

[R.Mesri]

Yes, studying group theory and differential geometry would be beneficial for your Quantum Field Theory class. A good place to start is by finding an online course or tutorial on these topics. Khan Academy is a great resource, and Coursera and edX have some great free courses as well. Additionally, there are many textbooks available which can provide more in-depth explanations and examples. Once you have a basic understanding of the topics, you can then focus your energy on the Quantum Field Theory material.