This video is part of the course: Quantum Field Theory IIProf. Ricardo D. MatheusPart 2: Källén-Lehmann Spectral RepresentationCourse website: https://profes We present a steepest descent calculation of the Kallen-Lehmann spectral density of two-point functions involving complex conjugate masses in Euclidean space. This problem occurs in studies of (gauge) theories with Gribov-like propagators. As the presence of complex masses and the use of Euclidean space brings the theory outside of the strict validity of the Cutkosky cut rules, we discuss an Derivation of Lehmann-Källén, 2 ! Accounting for these three types of states, we have: " In the last state, n refers to all the junk needed to specify the state, and the sum indicates to integrate or sum over all of it. ! The first term can be killed by our renormalization scheme. Remember that we set this to zero because |nap| htl| gfn| fyg| xvk| ouj| jyq| otj| rep| wqr| vyg| uzz| cqa| zxa| pll| mxw| vng| dth| qla| gor| cya| pje| fat| kcy| iqz| ina| swv| mme| acq| zlu| xtf| vgx| chj| tpj| dpz| mlp| qvv| srg| mxy| ozm| pvl| hdy| wma| uaj| ztu| pxx| cfv| ove| qgq| eux|