Here is a reader from China. Your book is great and very inspiring, and I hope there could be more books like yours. ]]>

Your book is amazing! Currently trying to self-study QFT and reps, and your book is invaluable. Your work is great, and physics needs more authors like you!

]]>Your book is not only an excellent book but an enlighten and deep source for understanding quantum field theory, otherwise difficult to grasp it. Very well done and wishing you the best in your career.

]]>I think the formula (3.36) in your book should read “v’=qvq^{-1}”, because this is the formula for rotation of vectors, and the former formula (3.36) is for rotation of frames. So the last equation on the bottom of page 36 should also be corrected, then the (3.45) should read “v’_x=cos(2\theta), v’_y=sin(2\theta), v’_z=0” and so on the (3.46). Therefore we can get the consistent results with (3.24)(the corrected form from your errata).

BTW, you wrote a very delightful book, thank you!

Best,

Jia-Ji