Screened-Coulomb ansatz for the nonfactorizable radiative corrections to off-shell $W^+W^-$ production

Abstract

We demonstrate that the results of the complete first order calculation of the non-factorizable QED corrections to the single-inclusive cross-sections for e + e − → W + W − → 4 fermions could be very well reproduced by a simple physically motivated ansatz. The latter allows to take into account effectively the screening role of the non-Coulomb radiative mechanisms by introducing a dampening factor in front of the width-dependent part of the known first-order Coulomb correction, the so-called screened-Coulomb ansatz.

Measurement of the W boson mass and width in e+e- collisions at LEP

“…The unweighted events from KORALW include non-factorizable QED corrections [37] which effectively "screen" the Coulomb interaction [30] between the two W's. It is suggested [38] that the difference between this "screened" Coulomb correction and no Coulomb correction can be used to assess an uncertainty.…”

Electroweak corrections uncertainty on the W mass measurement at LEP

“…• no Coulomb correction, Khoze-Chapovsky ansatz Coulomb correction [20] implemented through reweighting.…”

Measurement of the W-pair production cross-section and W branching ratios in e + e - collisions at $\sqrt{s}$ = 161-209 GeV

“…In order to estimate the effect that theoretical uncertainty in the description of the radiation had on the selection efficiency, the results obtained in the DELPHI setup were compared with a simulation making use of RacoonWW [34] on the testbench process udµν µ . The two programs differed in many respects in the treatment of QED radiation: YFSWW was a e + e − → W + W − → 4f generator (CC03 diagrams only) with O(α) factorisable electroweak corrections and nonfactorisable corrections implemented via the so-called Khoze-Chapovsky ansatz (KC) [38]. It included ISR in leading logarithm approximation (LL) O(α 3 ) via YFS exponentiation [39] and final state radiation (FSR) LL O(α 2 ) via PHOTOS [40].…”