STAR task force for tuning PYTHIA

[Yuanjing Ji <jiyj AT rcf.rhic.bnl.gov>]

Hi Raghav,
> 1) why do you have a BBC trigger in your code? We use that as a
> minbias trigger yes? and when you generate pythia, it is by definition
> having some activity in the event.  do you have cases where your BBC
> trigger fails?
I do observe there are some events that cannot be triggered. There are 
about ~90% MC events could be triggered in SoftQCD:nonDiffraction 
(regarded as minbias events) or HardQCD:all events. And nearly half of 
the events won't pass the trigger if we set a high mPtHat cut such as 
50<mPtHat<100 GeV. When I do the normalization, only the events that are 
triggered by BBC will be counted. I have checked that the spectra and 
particle ratios are consistent with or without BBC trigger.
> 2) when you fill the pT histograms, why do you fill with the inverse
> pT weight?
This weight is due to we are calculating pT spectra which is 
d^2N/(2pi*pT*dpT*dy).

Regarding the systematic shift in the comparison, I think probably it is 
due to the Pythia sample I generated are from HardQCD:all. The 
cross-section for HardQCD:all (66.7ub) is higher than 
SoftQCD:nonDiffraction (29.6ub). I now add a scale factor to scale back 
to STAR pp cross-sections (30ub in the paper) as the experiment 
observable is d^2N/(2pi*pT*dpT*dy). While I don't expect HardQCD:all 
events can describe low pT identified particle spectra, but there is 
still a shift at high pT:
https://drupal.star.bnl.gov/STAR/system/files/pythiatune0223.pdf

Best,
Yuanjing

On 2021-02-18 12:36, Raghav Kunnawalkam Elayavalli wrote:
> Hi Yuanjing,
>
> Thanks for your slides and sorry i wasnt able to attend the meeting
> yesterday. I have a couple of questions in your analysis - looking at
> your plots, while i would not expect pythia to exactly reproduce the
> data, it looks like there is a systematic shift in the comparison...
> 1) why do you have a BBC trigger in your code? We use that as a
> minbias trigger yes? and when you generate pythia, it is by definition
> having some activity in the event.  do you have cases where your BBC
> trigger fails?
> 2) when you fill the pT histograms, why do you fill with the inverse
> pT weight?
>
> Cheers
> Raghav
>
> **************************************
> Raghav Kunnawalkam Elayavalli
> email: raghav.ke AT yale.edu
>
> Associate Research Scientist
> Yale University and
> Brookhaven National Lab
> <he/him/his>
> **************************************
>
> > On Feb 17, 2021, at 3:16 PM, Yuanjing Ji via Star-tf-tunepy-l
> > <star-tf-tunepy-l AT lists.bnl.gov> wrote:
> >
> > Hi all,
> >
> > Please find my today's slides in the following link:
> > https://drupal.star.bnl.gov/STAR/system/files/pythiatune0217.pdf
> >
> > Thanks
> > Yuanjing
> >
> > On 2021-02-16 10:52, Matthew Kelsey via Star-tf-tunepy-l wrote:
> >
> > > Hi all,
> > > Let’s have our regular pythia 8 tuning task force meeting
> > > tomorrow
> > > (2/17) at 3 PM BNL time. I have copied the connection details
> > > below.
> > > Cheers,
> > > Matt
> > > ——————————
> > > Matthew Kelsey
> > > Postdoctoral Fellow
> > > Wayne State University
> > > <he/him/his>
> > > Topic: STAR PYTHIA 8 Tune Task Force
> > > Time: Feb 17, 2021 03:00 PM Eastern Time (US and Canada)
> > > Join Zoom Meeting
> https://urldefense.com/v3/__https://wayne-edu.zoom.us/j/98249789258?pwd=RVdncFY3Qk10bzBBMmphZlhGYmhUUT09__;!!P4SdNyxKAPE!VBTM27rty5TZxQlvhJT8wMYdVqr-tsMaSOGymXsqSp6BuiHTapPxKNZBaqviweiVOr9rOsogaDFg5Q$
> > > Meeting ID: 982 4978 9258
> > > Passcode: startune
> > > One tap mobile
> > > +13126266799,,98249789258# US (Chicago)
> > > +16468769923,,98249789258# US (New York)
> > > Dial by your location
> > > +1 312 626 6799 US (Chicago)
> > > +1 646 876 9923 US (New York)
> > > +1 301 715 8592 US (Washington DC)
> > > +1 408 638 0968 US (San Jose)
> > > +1 669 900 6833 US (San Jose)
> > > +1 253 215 8782 US (Tacoma)
> > > +1 346 248 7799 US (Houston)
> > > Meeting ID: 982 4978 9258
> > > Find your local number:
> https://urldefense.com/v3/__https://wayne-edu.zoom.us/u/adcP8hoYpn__;!!P4SdNyxKAPE!VBTM27rty5TZxQlvhJT8wMYdVqr-tsMaSOGymXsqSp6BuiHTapPxKNZBaqviweiVOr9rOsrc2bC5iw$
> > > _______________________________________________
> > > Star-tf-tunepy-l mailing list
> > > Star-tf-tunepy-l AT lists.bnl.gov
> > > https://lists.bnl.gov/mailman/listinfo/star-tf-tunepy-l
> > _______________________________________________
> > Star-tf-tunepy-l mailing list
> > Star-tf-tunepy-l AT lists.bnl.gov
> > https://lists.bnl.gov/mailman/listinfo/star-tf-tunepy-l