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Overview of Radiative Corrections. Chris Crawford 2005/6/30. Lowest Order Diagrams. Phase Space. k 2. k. k 1. t. q-k. f k. p 1. p 2. Radiative Amplitude. e. k 1. k 2. k 3. Soft Photon Approximation (SPA):. J m. Infrared divergence:. Peaking Approximation:. Bibliography.
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Overview of Radiative Corrections Chris Crawford 2005/6/30
Phase Space k2 k k1 t q-k fk p1 p2
Radiative Amplitude e k1 k2 k3 Soft Photon Approximation (SPA): Jm Infrared divergence: Peaking Approximation:
Bibliography • Bethe & Heitler, P.R.S.L.A 146, 83 (1934) • Schwinger, Phys. Rev.76, 790 (1949) • Yennie et al, Ann. Phys. 13, 379 (1961) • Mo & Tsai, Rev. Mod. Phys.41, 205 (1969) • Ent et al, Phys. Rev. C 64 054610 (2001) • Templon et al,Phys. Rev.C 61 014607 (2000) • Bardin & Shumeiko, Nucl. Phys.B 127, 242 • Afanasev et al, Phys. Rev. D64, 113009
SIMC (Ent et al) Unpolarized calculation Multiple photon angular distribution Soft photon approx. (SPA), Peaking approximation Explicit kinematic shifts AEEXB (Templon et al) Radiative unfolding trajectories in Em , pm pre-radiation, post-radiation MASCARAD (Afanasev) based on POLRAD (DIS) Polarization calculation No approximations No cutoff parameter Kinematic corrections implicit in cross section Leptonic vs. hadronic vars. Only partial handling ofmultiple photon emission Cutoff reintroduced in Monte Carlo generator Comparison of Calculations
Details of SIMC • SPA ) factorized correction • Integrate over k up to DEm • IR divergence cancelled by vertex correction • Exponentiation for multiple photons • Peaking Approx. ) delta function in Wk • Integration over multiple photon amplitude • Keep dependence of Etot • Includes external bremsstrahlung • Both internal, external put into same form
Monte Carlo Generator • in the code, only sF depends on k • must reintroduce cutoff parameter vm • set at resolution of BLAST • generate delta correction below vm • generate full k = (v,t,fk) dependence above vm • must omit F0I from sF • major contribution