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Top mass from electroweak data
Nuclear Physics B (Proc. Suppl.) 16 (1990) 294-295 North-Holland
294
elect D . Haidt DESY, Hamburg Increasingly precise data are getting available on electroweak quantities. These data can be interpreted within the theory of electroweak interactions (QFD) in terms of a set of free parameters, namely the finestructure constant a, the fermion rrrasses mf, the weak gauge boson masses mW and mZ and the Higgs mass mH . The confrontion of theory with data is carried out taking into account electroweak radiative effects, which depend on the mass of the top quark and to a lesser extent on the mass of the Higgs boson . Assumtions in the fit procedure are e the theory in its minimal form, i.e. weak neutral and weak charged interactions occur at equal strength the on-shell renormalisation scheme [7] ® the Higgs mass is fixed :
mH
= 100 GeV
In the on-shell scheme sin 20W is a derived quantity and defined by m2 m.Z
The precise value of the muon lifetime is used to define the Fermi coupling constant G. 1980 Sirlin [6] derived the following relation mw
= f(a, G, sin 2 0W, mf , mH ) _ ira 1 1 sinOw ~~G r 1 0 (a, G, mt, " . .) 37.281GeV 1 sinOW 1 - Or(a G m )
As a consequence, the numerical prediction of electroweak quantities is limited mainly by the uncertainty of two parameters, for instance mt and *Contribution to the FPS conference on Physics, Madrid, September 1989 .
High
e
Energy
0920-56.32/90/$3.50 @ Elsevier Science Publishers 13 .V . North-Volland
ta
New data have been presented to the Lepton-Photon Conference at Stanford in August 1989. The new measurements on the weak gauge bosons are listed in table 1 and conveniently illustrated in the (m2, mZ mw) plot of figure 1 together with the new mea,, SLC [1] UA 2 121 CDF [3] Average
e use the precisely measured 1c lifetime
sin20W = 1 -
sin20W . A simultaneous fit of all electroweak data leads to a constraint in the mass of the top quark, provided all data are consistently descibed within the framework of QFD.
W
_
80.0±0.4±0.4±1 .2 80.0±0.2±0.5±0.3 80.32 ± 0.47
91.17+0.18 90 .2±0.6±1.4 90 .9±0.3±0 .2 91 .10 ± 0.16
Table 1: New gauge boson masses (in GeV). In the averages the correlations are taken into account surement of sin2 0W of the CHARM II group [4] . It is derived from the ratio v,,e/-v,,e taking into accounc radiative corrections . The value for sin2 0w is higher than, but compatible with,their earlier determinations . The data shown in figure 1 are in good agreement with each other . Their combined result is shown by the hatched ellipse . The interpretation within QFD is straigiitforward sin2 0W ®r
)2 = 0.223 ± 0.009 1 - ( 1 __ ( 372281GeV )2 /(1 mw
0.033 :-+- 0.029
(~)2) m7
The constraint on the top quark mass from these data alone is not very strong . It gets tighter when combined w::_ all the previously published data. The status of electroweak data published since the discovery of weak neutral currents until April 1989, in the various sectors (namely fixed target, e4 e®,
D. Haidt /Top mass from electroweak data
C®nc
295
si
All electroweak data available up to September 1989 can be consistently interpreted within QFD. In achieving a good fit radiative corrections play an important role. The fit constrains the top quark mass to . mt = 135 f 35 GeV 78 GeV < mt < 188 GeVat 90 % CL independent ofthe value for sin'Ow . Similar results have been obtained by other authors [8,9] .
New data from SLC, UA2, CDF and CHARM II; the hatched ellipse is the combination of these data Figure 1 :
GeV
0231 _= uOGeV;' ----0229 1 0227 -025 0223 --105
tô
All data combined
,
\.
905
[2] A. Weidberg : Proc. of the ILP 1989
[4] J.Panman : Proc. of the ILP 1989 [5] D. Haidt : Status of the electroweak model, DESY 89-73 (July 1989) [6] A. Sirlin : Phys.Rev. D22 (1980) 971
"'
7onv _ ~,;
É
[1] G . Feldman : Proc. of the ILP 1989 [3] F. Abe et al.: Phys.Rev.Lett. 62 (1989) 1005; M.K. Campbell : Proc. of the ILP 1989
Status Aug 119
115
e e e Ces
910
t ,,
Newdata at Lepton Photon Conference Aug 1989 915
GeV
Figure 2: Impact of electroweak data (for explana-
tions see text)
pp experiments) has been summarized and interpreted by several authors (see [5] and references therein) . The region allowed by the 'old' data in the (mz,m. Z - may) plane is shown in figure 2 by the dash-dotted line together with the 'new' data (dotted line) taken over from figure 1. The new data are well compatible with the old ones. The overall combination is shown as the hatched ellipse corresponding to the 1Q contour . Obviously mZ is dominated by the new data, whereas mZ - mw is dominated by the old data, largely by vq data (including the uncertainty due to the charmed quark mass) . Also shown in the figure is the constraint obtained in the CDF top quark search .
[7] W. Hollik : DESY 88-188 (Dec. 1988) [8] J.Ellis and G.L.Fogli : Implications of recent electroweak data for mt and mX, CERN-TH 5511/89 and BARI-TH 89/60 [9] P.Langacker : Implications of recent mZ,w and NC measurements for mt, UPR 0400 T (September 1989)
294
elect D . Haidt DESY, Hamburg Increasingly precise data are getting available on electroweak quantities. These data can be interpreted within the theory of electroweak interactions (QFD) in terms of a set of free parameters, namely the finestructure constant a, the fermion rrrasses mf, the weak gauge boson masses mW and mZ and the Higgs mass mH . The confrontion of theory with data is carried out taking into account electroweak radiative effects, which depend on the mass of the top quark and to a lesser extent on the mass of the Higgs boson . Assumtions in the fit procedure are e the theory in its minimal form, i.e. weak neutral and weak charged interactions occur at equal strength the on-shell renormalisation scheme [7] ® the Higgs mass is fixed :
mH
= 100 GeV
In the on-shell scheme sin 20W is a derived quantity and defined by m2 m.Z
The precise value of the muon lifetime is used to define the Fermi coupling constant G. 1980 Sirlin [6] derived the following relation mw
= f(a, G, sin 2 0W, mf , mH ) _ ira 1 1 sinOw ~~G r 1 0 (a, G, mt, " . .) 37.281GeV 1 sinOW 1 - Or(a G m )
As a consequence, the numerical prediction of electroweak quantities is limited mainly by the uncertainty of two parameters, for instance mt and *Contribution to the FPS conference on Physics, Madrid, September 1989 .
High
e
Energy
0920-56.32/90/$3.50 @ Elsevier Science Publishers 13 .V . North-Volland
ta
New data have been presented to the Lepton-Photon Conference at Stanford in August 1989. The new measurements on the weak gauge bosons are listed in table 1 and conveniently illustrated in the (m2, mZ mw) plot of figure 1 together with the new mea,, SLC [1] UA 2 121 CDF [3] Average
e use the precisely measured 1c lifetime
sin20W = 1 -
sin20W . A simultaneous fit of all electroweak data leads to a constraint in the mass of the top quark, provided all data are consistently descibed within the framework of QFD.
W
_
80.0±0.4±0.4±1 .2 80.0±0.2±0.5±0.3 80.32 ± 0.47
91.17+0.18 90 .2±0.6±1.4 90 .9±0.3±0 .2 91 .10 ± 0.16
Table 1: New gauge boson masses (in GeV). In the averages the correlations are taken into account surement of sin2 0W of the CHARM II group [4] . It is derived from the ratio v,,e/-v,,e taking into accounc radiative corrections . The value for sin2 0w is higher than, but compatible with,their earlier determinations . The data shown in figure 1 are in good agreement with each other . Their combined result is shown by the hatched ellipse . The interpretation within QFD is straigiitforward sin2 0W ®r
)2 = 0.223 ± 0.009 1 - ( 1 __ ( 372281GeV )2 /(1 mw
0.033 :-+- 0.029
(~)2) m7
The constraint on the top quark mass from these data alone is not very strong . It gets tighter when combined w::_ all the previously published data. The status of electroweak data published since the discovery of weak neutral currents until April 1989, in the various sectors (namely fixed target, e4 e®,
D. Haidt /Top mass from electroweak data
C®nc
295
si
All electroweak data available up to September 1989 can be consistently interpreted within QFD. In achieving a good fit radiative corrections play an important role. The fit constrains the top quark mass to . mt = 135 f 35 GeV 78 GeV < mt < 188 GeVat 90 % CL independent ofthe value for sin'Ow . Similar results have been obtained by other authors [8,9] .
New data from SLC, UA2, CDF and CHARM II; the hatched ellipse is the combination of these data Figure 1 :
GeV
0231 _= uOGeV;' ----0229 1 0227 -025 0223 --105
tô
All data combined
,
\.
905
[2] A. Weidberg : Proc. of the ILP 1989
[4] J.Panman : Proc. of the ILP 1989 [5] D. Haidt : Status of the electroweak model, DESY 89-73 (July 1989) [6] A. Sirlin : Phys.Rev. D22 (1980) 971
"'
7onv _ ~,;
É
[1] G . Feldman : Proc. of the ILP 1989 [3] F. Abe et al.: Phys.Rev.Lett. 62 (1989) 1005; M.K. Campbell : Proc. of the ILP 1989
Status Aug 119
115
e e e Ces
910
t ,,
Newdata at Lepton Photon Conference Aug 1989 915
GeV
Figure 2: Impact of electroweak data (for explana-
tions see text)
pp experiments) has been summarized and interpreted by several authors (see [5] and references therein) . The region allowed by the 'old' data in the (mz,m. Z - may) plane is shown in figure 2 by the dash-dotted line together with the 'new' data (dotted line) taken over from figure 1. The new data are well compatible with the old ones. The overall combination is shown as the hatched ellipse corresponding to the 1Q contour . Obviously mZ is dominated by the new data, whereas mZ - mw is dominated by the old data, largely by vq data (including the uncertainty due to the charmed quark mass) . Also shown in the figure is the constraint obtained in the CDF top quark search .
[7] W. Hollik : DESY 88-188 (Dec. 1988) [8] J.Ellis and G.L.Fogli : Implications of recent electroweak data for mt and mX, CERN-TH 5511/89 and BARI-TH 89/60 [9] P.Langacker : Implications of recent mZ,w and NC measurements for mt, UPR 0400 T (September 1989)