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)
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