- #1
koolmodee
- 51
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[tex]\frac{1}{x-i\epsilon}[/tex]=[tex]\frac{x}{x²+a²}[/tex]+[tex]\frac{ia}{x²+a²}[/tex]= P [tex]\frac{1}{x}[/tex]+i pi [tex]\delta[/tex](x)
P means the principal value, a is possibly infinitesimal (?), i is the imaginary unit
Where does the pi, Dirac delta come from? What principal value?
It is from a quantum field theory book.
P means the principal value, a is possibly infinitesimal (?), i is the imaginary unit
Where does the pi, Dirac delta come from? What principal value?
It is from a quantum field theory book.
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