Hi.(adsbygoogle = window.adsbygoogle || []).push({});

I would like to ask a question about Chapter 15 in Srednicki's QFT book.

In chapter 15, after eq. (15.12), he compares eq. (15.12)

## \mathrm{Im}\bm{\Delta}(k^2)=\frac{\mathrm{Im}\Pi (k^2)}{(k^2+m^2-\mathrm{Re}\Pi (k^2))^2 + (\mathrm{Im}\Pi (k^2))^2}##

with eq. (15.8)

##\mathrm{Im}\bm{\Delta}(k^2)=\pi \delta(k^2+m^2)+\pi\rho(-k^2).##

Then he gets eq. (15.13)

##\pi \rho(s)=\frac{\mathrm{Im}\Pi (-s)}{(-s+m^2-\mathrm{Re}\Pi (-s))^2 + (\mathrm{Im}\Pi (-s))^2}.##

Why does ##\pi \delta(k^2+m^2)## disappears?

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# The one-loop correction in Lehmann-Kallen form

Loading...

Similar Threads for loop correction Lehmann |
---|

A Does the Frauchiger-Renner Theorem prove only MWI is correct |

I Is Bell's Theorem correct? |

B Am I understanding the intepretations correctly? |

B Correct English convention for |Psi|^2? |

**Physics Forums | Science Articles, Homework Help, Discussion**