STAR HardProbes PWG

["Ma, Rongrong" <marr AT bnl.gov>]

Hello Olga

Thanks for the explanation. I was confused by that one can directly subtract UE from signal in the dPhi projection, but not for the dEta projection (one needs to use the range of 0.5 < |dEta| < 1.0). I understand now. Thanks. 

Best

Rongrong

On Mar 22, 2023, at 9:40 PM, Evdokimov, Olga <evdolga AT uic.edu> wrote:

Dear Rongrong,

 

I am not sure I understand your questions. The correlation is built in full 2D. The projections shown are simple “control plots” – the easiest ways to check the normalization, the ME correction, etc.  They are done by standard root tools over desired histogram range along one axis onto the other. So to show the jet peak region, say, on dphi, we can select an deta stripe of +/-0.5,  project it of dphi, and then to overlay with background, we same way select the stripes at deta 0.5-1.0 and -0.5- -1.0 and project on dphi (at which point, both dPhi projections are 1 D histograms and since we projected both times across one unit of dEta the normalization is the same for both)…

 

One could do the same in the other direction, but due to vn the bg level matching is not assured. I note that from the original STAR ridge paper and many 2D  correlations analyses to follow, we are doing exact same thing, so perhaps, I really missing your concern, please explain.

 

Finally, the circular integration is no different in principle, but does not have built-in tools. But put it simply, you just follow a desired deta, dphi selection and project (copy) the chosen bins into a 1D histogram.

 

Best regards,

Olga

 

From: Ma, Rongrong <marr AT bnl.gov> 
Sent: Wednesday, March 22, 2023 8:23 PM
To: Evdokimov, Olga <evdolga AT uic.edu>
Cc: STAR HardProbes PWG <star-hp-l AT lists.bnl.gov>; Dale-Gau, Gabe <gdaleg2 AT uic.edu>
Subject: Re: [Star-hp-l] [Star-talks-l] Updated Slides for Hard Probes 2023 (Gabe)

 

Hello Olga 

 

Thanks for the explanation. I agree that using regions of |deta| < 0.5 and large dphi is not a good idea. 

 

Then how exactly do you get the UE distribution shown on the backup slides? Is it integrated over all dphi values, excluding the jet cone?

 

Best

Rongrong

On Mar 22, 2023, at 6:02 PM, Evdokimov, Olga <evdolga AT uic.edu> wrote:

 

    Dear Rongrong,

 

For biggest jets we, naturally, have the smallest acceptance. The plot on slide 4 shows correlations for R=0.3 jets; these are reconstructed up to (1-R)=0.7 in eta, which  together with the charged hadron selection of +/- 0.5 give the deta acceptance of +/-1.2

 

For your second question – one could not use |deta|<0.5 for UE; this is where the jet peak sits. Please take a look at slide 5 where jet and EU regions are sketched to illustrate this. If you propose to use +/- 0.5 in deta but “go away” from jet in dphi – we have considered this possibility in this and other such analyses, and this route is prohibited by the vn presence and the unknown jet-to-RP coupling (as well as presence of away side quenched jet which is not modeled well in any event generators to date). 

 

Best regards,

Olga

 

 

From: Star-hp-l <star-hp-l-bounces AT lists.bnl.gov> On Behalf Of Ma, Rongrong via Star-hp-l
Sent: Wednesday, March 22, 2023 3:45 PM
To: Dale-Gau, Gabe <gdaleg2 AT uic.edu>
Cc: STAR HardProbes PWG <star-hp-l AT lists.bnl.gov>
Subject: Re: [Star-hp-l] [Star-talks-l] Updated Slides for Hard Probes 2023 (Gabe)

 

Hello Gabe, Olga 

 

Thanks for your responses. 

 

For R = 0.5 jets, I understand that the eta cut o jets is |eta_jet| < 0.5. Do you also use |eta_track| < 0.5 cut which limits the dEta range from -1 to 1? It does not seem to be the case as one can see entries beyond |dEta| = 1 on slide 4. If your cut on tracks is |eta_track| < 1.0, it shouldn't be so difficult to get to |dEta| = 1, right?

 

On the second backup slide, you show the dEta distribution for UE (red points). Do you use UE within 0.5 < |dEta| < 1.0 for the projection of dPhi? If so, why not use the |dEta| < 0.5 range? Actually, how do you get the entries within |dEta| < 0.5 in the first place given that the UE semi-circles are far away from the jet axis in eta?

 

Sorry for these naive questions. I should have followed the analysis more closely. 

 

Best

Rongrong

On Mar 22, 2023, at 3:38 PM, Gabe Dale-Gau <gdaleg2 AT uic.edu> wrote:

 

Rongrong, 

 

To add to Olga's response, the reason we see this effect specifically in the center bins of dphi in R05 and not in the other dphi bins is due to the semicircular geometry employed in our UE definition. This is highlighted on slide 22 in backup. For all other R the semicircle does not reach the edge of our distribution in deta, but for R05 specifically, the area reaches the edge around dphi = 0.

 

Best,

 

Gabe

 

On Wed, Mar 22, 2023 at 10:04 AM Ma, Rongrong <marr AT bnl.gov> wrote:

Hello Gabe 

 

Thanks for including those backup slides. 

 

If I understand correctly, what you mean is that the UE distribution close to the edge (|deta| ~ 1) has large error bars, which contributes to the large errors seen in dphi ~ 0. Is this correct? If so, why don't they contribute to other dphi bins? Also, since your jet-hadron range is 0.5, I would naively expect you only use UE within |deta| < 0.5. Do I miss anything?

 

Best

Rongrong

On Mar 21, 2023, at 4:21 PM, Gabe Dale-Gau via Star-talks-l <star-talks-l AT lists.bnl.gov> wrote:

 

Conveners, 

 

Thank you for all of your comments and input. 

I have updated my Star-Talks submission here:

https://drupal.star.bnl.gov/STAR/presentations/Hard-Probes-2023/Baryon-Meson-Ratios-AuAu-and-pp-collisions-sqrtsNN-200-GeV

 

I have implemented many changes in this version to address all of the comments I received from Nihar and Barbara, as well as general rephrasing throughout to simplify text on slides.

 

Rongrong, the first three slides in the backup section are included to address your question about the origin of two strange points in the Au+Au correlated jet peak signal.

 

I will create a separate drupal page with figures included as individual files shortly.

 

Let me know if you have further questions or comments.

 

Many thanks,

 

Gabe

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