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Unformatted text preview: ous couplings (see Fig. 20 for
the 1D projections).
There are several ways to relate the WW and WWZ
couplings in the presence of new physics. This is a convenient
prescription to reduce the number of parameters since WW
production involves both WW and WWZ couplings.
Enforcing SUð2ÞL Uð1ÞY symmetry introduces two
relationships between the remaining parameters: Z ¼ gZ À
1
ð À 1Þtan2 W and Z ¼ , reducing the number of free
parameters to three (De Rujula et al., 1992; Hagiwara et al.,
1993). Alternatively, enforcing equality between the WW and WWZ vertices (WW ¼ WWZ) such that ¼ Z ,
¼ Z , and gZ ¼ 1 reduces the number of free parameters
1
to two.
In the D0 analysis, the onedimensional 95% C.L. limits
for Ã ¼ 2 TeV are determined to be À0:54 < Á < 0:83,
À0:14 < ¼ Z < 0:18, and À0:14 < ÁgZ < 0:30 under
1
the SUð2ÞL Uð1ÞY conserving constraints, and À0:12 <
Á ¼ ÁZ < 0:35, with the same limits as above, under
the WW ¼ WWZ constraints. One and twodimensional
95% C.L. limits are shown in Fig. 21. In the CDF analysis,
only 1D limits on the anomalous coupling parameters under
the assumption of SUð2ÞL Uð1ÞY invariance are reported.
The expected and observed 95% conﬁdence limits are shown
in Table XI where it is evident that the limits are weaker than
expected. The probability of observing these limits in the
presence of only SM WW production ranges from 7.1% to
7.6% depending on the coupling parameters (Z , Á , ÁgZ )
1
and are consistent with a statistical ﬂuctuation of SM physics. The WZ ﬁnal state is not available in eþ eÀ collisions at
"
LEP but can be produced in pp collisions at the Tevatron. The
study of associated production of a W and Z boson is 0
0.1 0.4 Expected
Observed
Expected
Observed ¼ Z 5. WZ 0.1
λγ=λZ 0.2
∆ gZ 0
0.2 0.4 TABLE XI. Expected and observed limits from the CDF
WW ! ‘‘ analysis searching for anomalous TGCs assuming
two different values of the form factor scale Ã (Aaltonen et al.,
2010a). For each coupling limit set, the two other couplings are
ﬁxed at their SM values. Values of the couplings outside of the given
observed range are excluded at the 95% conﬁdence level (C.L.). 10 0 1493 0.2
0.4 0.2 0 0.2 0.4
λγ 0.4 0.2 0 0.2 0.4
∆κγ=∆κZ FIG. 21. One and twodimensional 95% C.L. limits for the D0
WW ! ‘‘ analysis (Abazov et al., 2009e) when enforcing
SUð2ÞL Uð1ÞY symmetry at Ã ¼ 2 TeV, for (a) Á vs ,
(b) Á vs ÁgZ , and (c) vs ÁgZ , each when the third free
1
1
coupling is set to its SM value; limits when enforcing the WW ¼
WWZ constraints are shown in (d). The curve represents the twodimensional 95% C.L. contour and the ticks along the axes represent the onedimensional 95% C.L. limits. An asterisk (*) marks the
point with the highest likelihood in the twodimensional plane.
Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 FIG. 22. Leadingorder (a) tchannel and (...
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 Energy

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