Measurements of the trilinear gauge boson couplings
WWγ and
WWZ are presented using the data taken by DELPHI in 1998 at a centre-of-mass energy of 189 GeV and combined with DELPHI data at 183 GeV. ...Values are determined for
Δg
1
Z
and
Δκ
γ
, the differences of the
WWZ charge coupling and of the
WWγ dipole coupling from their Standard Model values, and for
λ
γ
, the
WWγ quadrupole coupling. A measurement of the magnetic dipole and electric quadrupole moment of the
W is extracted from the results for
Δκ
γ
and
λ
γ
. The study uses data from the final states
jjℓ
ν,
jjjj, ℓ
X,
jjX and
γX, where
j represents a quark jet, ℓ an identified lepton and
X missing four-momentum. The observations are consistent with the predictions of the Standard Model.
Neutral Higgs bosons of the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM) were searched for in the data collected in 1999 by the DELPHI experiment at centre-of-mass ...energies between 191.6 and 201.7 GeV with a total integrated luminosity of 228 pb(-1). These analyses, in combination with our results at lower energies, set 95% confidence level lower mass bounds on the Standard Model Higgs boson (107.3 GeV/c(2)) and on the lightest neutral scalar (85.9 GeV/c(2)) and neutral pseudoscalar (86.5 GeV/c(2)) Higgs bosons in representative scans of the MSSM parameter space. An extended scan of the MSSM parameter space was also performed to test the robustness of these limits.
We search for a low-mass scalar C P -odd Higgs boson, A 0 , produced in the radiative decay of the upsilon resonance and decaying into a τ + τ − pair: Υ ( 1 S ) → γ A 0 . The production of Υ ( 1 S ) ...mesons is tagged by Υ ( 2 S ) → π + π − Υ ( 1 S ) transitions, using a sample of ( 98.3 ± 0.9 ) × 10 6 Υ ( 2 S ) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3.5 ≤ m A 0 ≤ 9.2 GeV , and combine these results with our previous search for the tau decays of the light Higgs in radiative Υ ( 3 S ) decays, setting limits on the coupling of A 0 to the b ¯ b quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of the next-to-minimal-supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom.
In 1996 LEP ran at a centre-of-mass energy of 161 GeV, just above the threshold of W-pair production. DELPHI accumulated data corresponding to an integrated luminosity of 9.93 pb
−1, and observed 29 ...events that are considered as candidates for W-pair production. From these, a cross-section for the doubly resonant e
+e
− → WW process of 3.67
−0.85
+0.97 ± 0.19 pb has been measured. Within the Standard Model, this cross-section corresponds to a mass of the W-boson of 80.40 ± 0.44 (stat.) ± 0.09 (syst.) ± 0.03 (LEP) GeV/
c
2. Alternatively, if
m
W is held fixed at its current value determined by other experiments, the observed cross-section is used to obtain limits on trilinear WWV (V ≡ γ, Z) couplings.
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