sPHENIX cold QCD topical group

[Ralf Seidl <rseidl AT rcf.rhic.bnl.gov>]

Hi Dave,

my guess is that STAR has the forward Calorimeter with pre-shower to 
study not only forward back-to-back di-hadrons but also hadron-photon 
combinations in search of the color-glass condensate. They had a recent 
paper on the di-hadrons from p+Al and p+Au on which they want to build.
Unfortunately everything related to the CGC requires very asymmetric 
collisions and very forward (or rather backward of the A-going 
direction) instrumentation to reach the low x.
Together with many transverse spin asymmetries being largest in the 
forward direction these p+A measurements were part of or our motivations 
to suggest a forward sPHENIX...
At central rapidities you can improve the nuclear PDFs and the nuclear 
fragmentation functions a bit, but nothing that is absolutely essential 
for the EIC physics program.
In support of the p+Au program we have the rather unique charged hadron 
asymmetries that Jeongsu discovered to decrease in p+Au in PHENIX. We 
can definitely extend on these measruements between the former PHENIX 
muon arm rapidities and the central charged pion asymmetries from 
PHENIX. Those figures can be already found in the BUPs, of course.
Maybe others have more comments on that.

Cheers,

Ralf


On 2023-09-12 11:06, David Morrison via sPHENIX-cold-QCD-l wrote:
> Dear sPHENIX cold QCD'ers,
>
> We received this homework question this evening from the chair of the
> PAC, John Harris:
>
> > Question to STAR and sPHENIX:
> > Please provide us with the plots (from the literature? from recent
> > conference talks by theorists? or from your own efforts?) that
> > support what you see as a crisp example of how a specific pAu
> > measurement (either polarized or unpolarized) made in the closing
> > years of the RHIC program can be compared to which specific future
> > eA measurement from the EIC, and what this comparison can teach us.
> > Which is to say please share what you see as “the money plot”
> > making the case that a specific pAu measurement is particularly
> > important to enhancing the science impact of the future EIC program.
>  The context is that STAR argued in general terms during the PAC
> presentations that p+Au data in Run-24 is critical for understanding
> key EIC measurements.  Saturation and universality were mentioned.
> When pressed on this point, however, they didn't have a specific plot
> to show.
>
> If we have such a plot and it's particularly compelling, we could
> include it in our answer to this question.  We would need to have it
> before about 8am ET on Tuesday morning for it to be useful.
>
> Regards,
> Dave
>
> --
> David Morrison  Brookhaven National Laboratory  phone: 631-344-5840
>                 Physics Department, Bldg 510 C    fax: 631-344-3253
>                           Upton, NY 11973-5000  email: dave AT bnl.gov
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