deletions | additions       diff --git a/Beam energy measurement.tex b/Beam energy measurement.tex  index 30b6068..0a58355 100644  --- a/Beam energy measurement.tex  +++ b/Beam energy measurement.tex 
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At TLEP, instead, it is possible to inject a few non-colliding bunches out of the 4400 (Z pole) or 600 (WW threshold) colliding bunches without significant loss of luminosity, and apply resonant spin depolarization on those. The beam energy will therefore be measured continuously, in the exact same conditions as for the colliding bunches, with a statistical accuracy of 100 keV or (much) better. A precision of 0.1 MeV or better is therefore at hand for the Z width measurement, and the beam energy knowledge is not a concern for the W mass measurement at the WW threshold.  At higher centre-of mass energies, the beam energy can be determined from the precise knowledge of the Z mass with (i) the $\epemto {\rm Z}\gamma$ process~\cite{cite:0506115}; and (ii) the $\epemto {\rm ZZ}$ process; making use of the energy-momentum conservation in the kinematic fits. Whit five years of data taking at $\sqrt{s} = 240$ GeV, these two processes allow the average beam energy (and its spread) with a statistical precision better than 1 MeV. With five years of data taking at $\sqrt{s} = 350$ GeV, the knowledge of the W mass and the $\epemto {\rm WW}$ production are tools of choice for the beam energy determination in a scan of the $\ttbar$ threshold, with a similar statistical precision of 1 MeV or better.