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Hi, I believe Sven is right. As you say, it is hard to see how to improve alpha_S without a dedicated facility/program and no such thing is planned as far as I know. This is an important - even key - question so it deserves study. Perhaps Sven's talk provides the right starting point. Michael On Apr 18, 2013, at 1:36 AM, Sven Heinemeyer <[log in to unmask]> wrote: > Hi Michael, > >> The question for you is, how much would the extra factor of 10 at the Z pole (or the >> extra factor of 100 beyond Giga-Z) buy you in terms of the physics? My quick impression >> is that it is not easy to convert the extra luminosity into physics. GF and MZ must be >> improved, and NNLO electroweak becomes relevant. The uncertainty in alpha(mZ) also >> needs improvement, and I do not see a way to do that. >> > When we make GigaZ predictions for sin2eff, MW etc. we already use > a very optimistic assumption on delta(Delta alpha_had) = 5 x 10^-5, > resulting in an uncertainty of 1.8 x 10^-5 in sin2eff, i.e. even > larger than the anticipated GigaZ uncertainty, see p. 7 of my talk > at the BNL meeting a few weeks back: > http://www.ifca.unican.es/users/heinemey/uni/talks/2013/SnowmassBNLEWPO.pdf > > On the next page I give an estimate of intrinsic uncertainties, i.e. due > to missing higher-order corrections. Also here in the future the > GigaZ result can be matched only "so-so", and even less so in the MSSM, > which is the *only* model so far in which these quantities have been evaluated to a precision roughly as in the SM, it is much worse in any other model. > > Of course in the future many things are possible. But our expectations > now (which are not wild guesses ;-) would not profit from another > factor of 10 improvement. > > Cheers, > Sven > > > ******************************************************************************* > Sven Heinemeyer (IFCA (CSIC-UC), Santander, Spain) > The future is not set! > phone: ++34/942/20-1536, fax: -0935 > There is NO FATE but > email: Sven.Heinemeyer(at)cern.ch > what we make for > WWW : sven-heinemeyer.de > ourselves! > skype: sven.heinemeyer > (Kyle Reese, T2) ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the SNOWMASS-ELECTROWEAK list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=SNOWMASS-ELECTROWEAK&A=1