The process e(+)e(-)-->W(+)W(-)gamma is analysed using the data collected with the L3 detector at LEP at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.8 pb(-1). Based on a sample of 42 selected W+W- candidates containing an isolated hard photon, the W(+)W(-)gamma cross section, defined within phase-space cuts, is measured to be: sigma(WW gamma) = 290 +/- 80 +/- 16 fb, consistent with the Standard Model expectation. Including the process e(+)c(-)-->upsilon<(upsilon)over bar>gamma gamma, limits are derived on anomalous contributions to the Standard Model quartic vertices W(+)W(-)gamma gamma and W(+)W(-)Z gamma at 95% CL: -0.043 GeV-2 < a(0)/Lambda(2) < 0.043 GeV-2, -0.08 GeV-2 < a(c)/Lambda(2) < 0.13 GeV-2, -0.41 GeV-2 < a(n)/Lambda(2) < 0.37 GeV-2. (C) 2000
Measurement of the W+W- gamma Cross Section and Direct Limits on Anomalous Quartic Gauge Boson Couplings at LEP.
GUIDA, Michele;QUARTIERI, Joseph;
2000
Abstract
The process e(+)e(-)-->W(+)W(-)gamma is analysed using the data collected with the L3 detector at LEP at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.8 pb(-1). Based on a sample of 42 selected W+W- candidates containing an isolated hard photon, the W(+)W(-)gamma cross section, defined within phase-space cuts, is measured to be: sigma(WW gamma) = 290 +/- 80 +/- 16 fb, consistent with the Standard Model expectation. Including the process e(+)c(-)-->upsilon<(upsilon)over bar>gamma gamma, limits are derived on anomalous contributions to the Standard Model quartic vertices W(+)W(-)gamma gamma and W(+)W(-)Z gamma at 95% CL: -0.043 GeV-2 < a(0)/Lambda(2) < 0.043 GeV-2, -0.08 GeV-2 < a(c)/Lambda(2) < 0.13 GeV-2, -0.41 GeV-2 < a(n)/Lambda(2) < 0.37 GeV-2. (C) 2000I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
