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hi Ayres and Sven, I hear you - but we are talking more than 20 years in the future. I am amazed at the progress in theory of higher order calculations over the past 20 years. No way do I see this "precision theory frontier" slowing down over the next 20 years. I am at the Instrumentation Frontier Snowmass workshop in Boulder and they talk of "grand challenges". To me, the discussion below also suggests a "grand challenge" in EWPO. regards, Ashutosh On Apr 18, 2013, at 10:26 AM, Ayres Freitas <[log in to unmask]> wrote: > Hi Michael, > > I second Sven's comments. I think going beyond GigaZ will be extremely challenging, both in terms the uncertainty of input parameters (mtop, alpha(mz), alpha_s), as well as higher-order calculations. Concerning the latter, we would need (at least) complete NNNLO, which is not completely inconceivable, but will require a hugh amount of effort, and I'm not sure if placing so much effort there is the best way to advance our field (and I am writing this as someone who at least partially makes a living from these calculations). See attachment for some more quantitative, but rough estimates of uncertainties from higher-order corrections that I made recently. > > Best, > Ayres > > > On Thu, 18 Apr 2013, Sven Heinemeyer 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 >> > > ######################################################################## > 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<therr.png> ######################################################################## 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