1. Overview of Radiative Corrections
Chris Crawford
2005/6/30

2. Lowest Order Diagrams

3. Phase Space k2 k k1 t
q-k p1 fk p2

4. Radiative Amplitude Soft Photon Approximation (SPA):k1 k2 k3
Soft Photon Approximation (SPA): Jm
Infrared divergence:
Peaking Approximation:

5. 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 (2001)
Templon et al, Phys. Rev. C (2000)
Bardin & Shumeiko, Nucl. Phys. B 127, 242
Afanasev et al, Phys. Rev. D 64,

6. Comparison of Calculations
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 of multiple photon emission
Cutoff reintroduced in Monte Carlo generator

7. 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

8. Details of MASCARAD

9. 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