
#1
Jul111, 02:24 AM

P: 270

Trivial question...
How exactly does the minus sign arise in eq. 43.10? The sentence below states because the functional derivative goes through one spinor, but I can't see how that works... book is online here http://www.physics.ucsb.edu/~mark/msqftDRAFT.pdf equation 43.10 is on pdf page 273 thank you 



#2
Jul111, 03:07 AM

P: 185

i'll take a shot.
let me argue by analogy, maybe making the rule plausible. suppose i have anticommuting numbers x,y,h. and i'm given the expression yx and i want to differentiate it with respect to x. lacking any better choice i form the difference quotient [tex]\frac{d}{dx}(yx) = \lim_{h \rightarrow 0} \frac{1}{h} ( y(x+h)  yx ) [/tex] [tex] = \lim_{h \rightarrow 0} \frac{1}{h} yh [/tex] now because the numbers are anticommuting i can't just cancel h. i have to first swap yh or h^(1) and y and then i can cancel. [tex] = \lim_{h \rightarrow 0}\left( y \frac{1}{h} h \right)= y [/tex] 



#3
Jul211, 04:04 AM

P: 270

qbert, I thank you very much!



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