LEP EW WG Plots for the Winter 2003 Conferences

Latest modifications / corrections as of March 7th, 2003.

You can find here the plots that have been produced for the Winter 2003 conferences. Some plots may show up here in a couple of slightly different presentations, depending on who has made the plot. They all use the same data. Many results and plots are still based on preliminary results.

Note that essentially the full set of plots will be made available, including those that have data that hasn't changed, so that "one-stop shopping" can be done.

Compared to summer-2002, changes occur in APV and M_W(LEP-2).

Answers to FAQs on plots presented below:

For plots showing generic SM predictions in form of arrows or areas, the following parametric variations are used: dal5had = 0.02761(36), alpha_s = 0.118(2), MZ = 91187.5(2.1) MeV, M_top = 174.3(5.1) 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!
Afb_q and R_q[=GZ_q/GZ_had] bar-chart plots for heavy quark flavours comparing ADLOS results:
- In contrast to previous versions of these plots for older conferences, all numerical values as well as all dots with error bars are so-called pole quantities, eg, Afb0q, and in particular corrected to exactly the same set of values for other parameters. When applicable, the measurements at the off-peak energy are transported to the peak and included in the results.
- Thus the results shown are directly comparable, among themselves as well as with the average, but do not neccessarily correspond digit-by-digit to the numerical values found in the individual experimental publications.
Epsilon-parameter contour
- Based on a fit varying alpha(dal5had), alpha_s, MZ, and the four epsilon_123b parameters
- Data set consists of all measurements except Gamma_W, M_top and sin2theta from NUTEV due to its explicit M_top/M_Higgs dependence (M_top/M_Higgs cannot be expressed in terms of the four epsilon parameters). APV is also not included, as additional model assumptions are needed to express APV in terms of the epsilon parameters.
STU-parameter contour
- Based on a fit varying alpha(dal5had), alpha_s, MZ, and the three STgamma_b parameters
- U=0 fixed throughout
- Data set consists of all measurements except Gamma_W, M_top and sin2theta from NUTEV due to its explicit M_top/M_Higgs dependence (M_top/M_Higgs cannot be expressed in terms of the four STUgamma_b parameters). APV is also not included, as additional model assumptions are needed to express APV in terms of the STUgamma_b parameters.
- The additional bands correspond to +-1sigma bands for the alpha_s independent quantities GZ_lepton, MW and sin2teff (in order of increasing slope dT/dS). GZ_lepton instead of GZ_tot is chosen because the latter depends in addition on alpha_s and the former exhibits a more extreme (ie, flatter) slope. All other fit parameters are fixed.
- The MSM reference values (STUgamma_b=0) are dal5had=0.02761, alpha_s=0.118, MZ=91.1875 GeV, M_top=175 GeV, M_Higgs=150 GeV
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=0.02761+-0.00036, alpha_s=0.118+-0.002, MZ = 91.1875+-0.0021 GeV and M_top=174.3+-5.1 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 should not be taken quantitatively.
- 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.