Hi,
Shouldn't the argument be on integrated luminosity (number of Z bosons), not instantaneous luminosity?
That's the who point of "Giga", right? 10^9 events.
This thread makes it sound like 10^36 = TeraZ, but here we only care whether we want 10^12 Z's or not.
Probably the way to look at this is from a detector readout point of view - for a 10^7 sec running year,
100kHz of Z bosons is quite still. Good luck running to tape at more than 1kHz. Put in the actual target number
of events needed for the physics, divide by the number of experiments, and factor in the DAQ readout rate
per experiment.
Unless there is a new background that appears in high inst. lump operation, the inst. lumi will set the length
of the running period at different energy points. You may find that the number of experiments plays a role
in the running period length as well and in reducing uncorrelated systematics.
The length of the program in years or running periods can always be translated for
the different facilities, and whether there is a need to reserve contingency if there are
elements of the machines that required head room in the design parameters.
The issue on inst. lumi is more relevant in cases where there are not enough events being produced
even for a long stretch of running - which is a bigger issue for Higgs physics.
Best,
Chris
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)
>>
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