in peskin-schroeder and http://www.hep.phy.cam.ac.uk/batley/particles/handout_04.pdf" the amplitude for e^-e^+\rightarrow \mu^- \mu^+ is written using feynman rules as follows
-iM=[\bar{v}(p_2)(-ie\gamma^\mu )u(p_1)] \frac{-ig_{\mu\nu}}{q^2}[\bar{u}(k_1)(-ie\gamma^\nu )v(k_2)]
but what...
ok, i have another question that should have came earlier
(p'\!\!\!\!\!/ \ -m)_{da}\gamma^\mu_{ab}(p\!\!\!\!\!/ \ +m)_{bc}\gamma^\nu_{cd}
=\operatorname{Tr}[(p'\!\!\!\!\!/ \ -m)\gamma^\mu(p\!\!\!\!\!/ \
+m)\gamma^\nu]
where the trace came from here?
\operatorname{tr}(8p'^\nu p^\mu) - \operatorname{tr}(2mp'^\mu \gamma^\nu) + \operatorname{tr}(2m\gamma^\mu p^\nu) + \operatorname{tr}(2m^2g^{\mu\nu})
am i on the right way?
ok tell me please how to trace this thing \operatorname{tr}(\gamma^\nu\gamma^\mu p'_\mu\gamma^\mu\gamma^\nu p_\nu)? why it can't show \operatorname{tr}(\gamma^\nu\gamma^\mu p'_\mu\gamma^\mu\gamma^\nu p_\nu)? the last is what i want to ask
yes, i just want to know how to get from the left hand side to the right hand side. the problem mabye is thas i am not familiar with traces of gamma matrices. i'll try to learn it then come with a more concrete question..
but if anybody can give some hints that helps i'll be grateful.
Hi everybody!
While reading Peskin-Schroeder, i stuck in the in equation 5.4 about the unpolarized cross section of the e^- e^+ \rightarrow \mu^- \mu^+ annihilation. i didn't understand how this relationof the electron trace came to be, and where the indices came from...
Volume between two surfaces?
hi guys,
i hope you can help with this, how to find the volume between those surfases:
x^2+y^2+z^2=0
z=\sqrt{x^2+y^2}
thanks in advance
thank you Javier, but sorry, I know nothing about group theory!
did you mean they are unified under another theory that doesn't describe the other interactions?
The fundamental forces: four or three?
They still counting them as four though the the elctromagnatic and the weak have been unified.
so why not three?
thanks