Precision predictions for (un)stable W+W- pair production at and beyond CERN LEP2 energies -: art. no. 093010

We present precision calculations of the processes e(+)e(-) --> 4 fermions, in which the double resonant W+W- intermediate state occurs. Referring to this latter intermediate state as the signal process, we show that, by using the YFS Monte Carlo event generators YFSWW3-1.14 and KORALW 1.42 in an appropriate combination, we achieve a physical precision on the signal process, as isolated with CERN LEP2 MC Workshop cuts, below 0.5%. We stress the full gauge invariance of our calculations and we compare our results with those of other authors where appropriate. In particular, sample Monte Carlo data are explicitly illustrated and compared with the results of the program RACOONWW of Denner In this way, we show that the total (physical and technical) precision tag for the WW signal process cross section is 0.4% for 200 GeV, for example. Results are also given for 500 GeV with an eye toward future linear colliders.