The resonant depolarization technique works up to Ebeam ~ 60 GeV. For higher energies, it's assumed a linear dependence of the Beam Energy with the Bending Field measured with the NMR probes. This linearity is cross checked by measuring the dependence of the Flux Loop w.r.t. the Bending Field. The uncertainty on the LEP Beam Energy quoted so far (~20 MeV) is dominated by the non-linearity of this test.

A more desirable situation would be to have a direct measurement of the LEP Beam Energy at high energies, so that the linear extrapolation is justified. This is why the LEP energy calibration group have been working on two alternative methods: The Synchrotron tune (Qs , see Anke talk) and Spectrometer methods.

The concept of the LEP Spectrometer Project is very simple. Put a triplet of Beam Position Monitors (BPM) in front of a LEP dipole, and another triplet of BPM after. Measure the bending angle, and from the known Bending field from the local NMR one gets the LEP Beam Energy. In fact, they do a relative measurement by calibrating the Beam Energy at 50 GeV with the Resonant Depolarization Method, ramping immediately to Physics Energy and measuring with the spectrometer. In 1999 they had 3 fills measured in this way, and the dispersion w.r.t. the NMR measurements was about 15 MeV centred around zero. The situation in the year 2000 is somehow very different. They have calibrated 4 fills (2 electron beams and 2 positron beams), giving inconsistent results. The positron fills are shifted by ~30 MeV, while the electron fills are shifted by ~130 MeV w.r.t. the NMR measurements. Moreover, the spectrometer data are internally inconsistent when the redundancy of the system is used to cross-check the results. Several hypotheses that could explain these discrepancies have been studied: Synchrotron radiation, bunch length, ambient fields, Beam size, X-Y cross-talk… but none has an effect large enough to explain the observations.

The Synchrotron tune (Qs) depends on the RF voltage and the Beam Energy. The measurement of the Qs as a function of the RF voltage allows the determination of the Beam Energy, by also fitting simultaneously the gain in the voltage (g) , additional energy losses (K) and a normalization factor (alpha_c). In 1999, 3 measurements at high energies were performed in agreement with the NMR measurements: E_QS - E_NMR = -9 +- 11. In the year 2000 only 2 measurements have been performed and they plan to have 2 more measurements before LEP shutdown. In contrast with 1999 data, the 2000 data shows an energy dependence of the fitted value for (g). This needs to be reproduced, and this is the main reason to request the 2 new measurements. The current understanding is that these new measurements requested do not interfere in a significative way with the High Energy running.

To quote Eric Torrence: " The uncertainty on Ebeam may not be reduced (from the quoted 20 MeV), but it is much believable…"

Hugo has produced the 4q W mass invariant distribution using the sample of data collected at energies above 205.5 GeV, with mean energy 206.7 GeV. Data look in very good agreement with the reweighted MC predictions. Jet corrections supplied by Franco were applied, but the effect is very small (30 MeV shift on the mean of the distribution). This plot is going to be shown by Fabio at the LEP fest.

Djamel has done a similar exercise than Hugo using the electron and muon channels. The agreement between data and MC is good even without reweighting.

The WW cross-sections have been updated with 79.2 pb-1 at 205.0 GeV average energy and 97.5 pb-1 at 206.7 GeV average energy. All results are in very good agreement with the "new" SM predictions from RACOONWW and YFSWW. Plots have been prepared and approved to be shown at the Thursday meeting in preparation for the LEP fest.

DELPHI has repeated the ALEPH analysis using double ratios (ratio like-sign over unlike-sign divided by the same ratio in MC), using the common MC files generated by ALEPH (CRETE files). The results are in very good agreement with the ALEPH results, agreement with NO BE between W's, and discrepancy with the LUBOEI implementation. The CRETE files (ALEPH tunning) is able to reproduce the double ratio on WW semileptonic events in DELPHI but do not reproduce the single ratio (unlike-sign over MC predictions). This was also confirmed by an analysis in L3, and Bolek has found a similar effect in ALEPH, by repeating the analysis using single ratios only. The tuning of the strenght of BE (l ) is performed on udsc tagged Z events using the double ratio. The fact that this tunning does not seem to work for other distributions than the double-ratio implies that it's not a physical parameter, and effectively other effects are included in this tunning. A first attempt to tune the MC using single ratios, and repeat the analysis with the ALEPH data has been performed by Bolek and gives consistent results with the results using the double ratio.

Scott gave a short summary on how the bin-to-bin correlations were computed in the Particle Flow Analysis submitted to Osaka. It seems that they were neglected by some of the other LEP experiments, and they have requested a internal note explaining the procedure. Scott has written an ALEPH note, and it was approved to circulate this note to the other LEP experiments.