LEP EW WG Plots for Winter 2007 / Summer 2007 unchanged

Latest corrections and/or modifications 16-March-2007.

You can find here the plots that have been updated for the Winter 2007 conferences. The plots are also valid for the Summer 2007 conferences because no updates of the input data have been received. Most results are final, such as the Z-pole measurements from SLD and at LEP. The LEP-2 results on the mass and width of the W boson are final but their combination is still preliminary.

Changes:

All fits on which all plots posted here are based, include the electroweak precision measurements made by SLD and LEP-1 in electron-positron collisions at the Z pole, described in the final Z-pole paper. Compared to the final Z-pole paper, the updated input measurements are:

mass of the top quark from the Tevatron (updated for winter 2007: final Run-I and preliminary Run-II results)
mass and width of the W boson from the Tevatron (updated for winter 2007: final Run-I and preliminary Run-II results)
mass and width of the W boson from LEP-2 (updated for summer 2006: final results from Aleph, Delphi, L3, Opal, but preliminary combination)

As before, version 6.42 of ZFITTER is used for SM calculations.

Attention:
Since winter 2004, the global SM fits now use only high-Q2 results from LEP, SLC and the Tevatron (together with the hadronic vacuum polarisation). This disentangles the numerical Higgs-mass constraint and limit from the issue of the high chi2 caused by the low-Q2 NuTeV measurement which, however, has only a small influence on the fitted Higgs mass. Based on these high-Q2 analyses, predictions for low-Q2 measurements such as atomic parity violation in cesium (APV), parity violation in Moller scattering (e-e-), and neutrino-nucleon scattering (NuTeV) are derived.

Answers to FAQs on plots presented below:

Only updated plots are collected on this page.
While the measurements of W mass and W width of all four LEP experiments are now final and used in the combination, the LEP combination itself is still preliminary as it uses a preliminary LEP-2 combined estimate for the effect of color reconnection.
For plots showing generic SM predictions in form of arrows or areas, the following parametric variations are used: dal5had = 0.02758(35), alpha_s = 0.118(3), MZ = 91187.5(2.1) MeV, M_top = 170.9(1.8) GeV, M_Higgs = 300+700-186 GeV (lower limit of 114 GeV as given by the direct search). The arrows are pointing in the direction of increasing parameter values!
Higgs constraint from each measurement:
- For each observable, the corresponding constraint on the Higgs mass is determined in a full MSM fit to the measurement result of this observable, constraining dal5had=0.02758+-0.00035, alpha_s=0.118+-0.003, MZ = 91.1875+-0.0021 GeV and M_top=170.9+-1.8 GeV.
- For Higgs masses larger than about 1 TeV, the MSM and its formulae used do not make too much sense, so that part of the Higgs mass regime is cut of as it should not be taken quantitatively.
- The vertical green band denotes the overall constraint on the Higgs mass derived from the fit to all data.
- The vertical black line denotes the limit on the Higgs mass obtained from the direct search at LEP-2.
- The effects of real Higgs-strahlung, Z*+H, is not taken into account, neither in the experimental analyses (such as Higgs-mass dependent efficiencies for various Z*H decay channels) nor in the calculation of MSM predictions (increased Z decay widths). Thus quantitative conclusions from individual observables are uncertain in the low Higgs-mass regime.

Enjoy!