Gauge Invariant YFS Exponentiation of (Un)stable W+W− Production At and Beyond LEP2 Energies†

We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated calculation of ee → WW → f1f̄ ′ 1 + f̄2f ′ 2 at and beyond LEP2 energies, where the left-handed parts of fi and f ′ i are the respective upper and lower components of an SU2L doublet, i = 1, 2. The problem of gauge invariance of the radiation from the unstable charged spin 1 W is solved in an entirely physical manner. Our formulas are illustrated in a proto-typical YFS Monte Carlo event generator YFSWW2, wherein both Standard Model and anomalous triple gauge boson couplings are allowed. To be submitted to Physical Review D † Work partly supported by the Polish Government grants KBN 2P30225206 and 2P03B17210 and by the US Department of Energy Contracts DE-FG05-91ER40627 and DE-AC03-76ER00515. ⋆ On leave of absence from Institute of Computer Science, Jagellonian University, Kraków, Poland. UTHEP-95-0801 August 1995