Recent content by Manu_

My naive attempt to expand the log was##log(k2+A2−λ)=log[(k2−λ)(1+A2(k2−λ))]=log(k2−λ)+log(1+A2(k2−λ))≈log(k2−λ)+A2(k2−λ)##but it did not help me so far since the second term vanishes. Can someone point me to the right direction?

Thanks King Vitamin, I will take a look in that textbook. Actually, there is a mistake in my first post, where I used (ig) instead of (-ig) for the coupling, and this changes the final result to (N-2) instead of (N+2). But I still have to find out how to edit my post...

I compared the results described in: https://zzxianyu.files.wordpress.com/2017/01/peskin_problems.pdf http://hitoshi.berkeley.edu/230A/HW4sol.pdf And the result found by Gross and Neveu in their paper: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.10.3235 The factor of ##g^2## found...

In the Peskin & Schroeder textbook, the ##\beta## function for the Gross-Neveu model is discussed in problem 12.2. After computing it, I have tried checking my results with some solutions found online. My problem is that they all disagree among each other (something quite recurrent for this book...

Hi! I took a look in this book and Radovanovic's, but they cover more or less what has been treated in P&S before problem 5.3. They do not mention Fierz identities used with spinor products.

Hi! Yes, I have seen this manual, but unfortunately, he states that this is all obvious...

Does anyone else have a suggestion? Thanks!

Thanks for the references, MathematicalPhysicist. But I took a look on these books, and all I saw was the general Fierz identities, and these are already treated in PS. However, I still don't see where does this result come from. I'm sure it's something basic, but I can't see it...

Hello, I am currently stuck on problem 5.3 (c) about spinor products in PS, where one needs to prove the Fierz identity: $$ \bar{u}_{L}(p_{1}) \gamma^{\mu} {u}_{L}(p_{2}) [\gamma_{\mu}]_{ab} = 2 [u_{L}(p_{2})\bar{u}_{L}(p_1) +u_{R}(p_{1})\bar{u}_{R}(p_2) ]_{ab} $$ They say that a Dirac matric M...

Thank you your answer, Vanhees, it got clearer for me now.

Hello everyone, I am trying to solve equation 4.77 (about cross-sections) in peskin/schroeder's book. They state that: \int d\bar{k}^{z}_{A} \delta \left( \sqrt{\bar{k}^{z}_{A}+m^{2}_{A}} + \sqrt{\bar{k}^{z}_{B}+ m^{2}_{B}} - \Sigma E_{f} \right) \Big{|}_{\bar{k}^{z}_{B}=\Sigma...

Hello everyone, I am trying to solve exercise 7.21 in the "Hobson, Efstathiou, Lasenby, General Relativity. An introduction for physicists." What is asked is to show that the parallel transportation of a vector, along a closed triangle on a 2-sphere, results in an vector orthogonal to the...