STAR HardProbes PWG

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

Hello Sooraj

I still have a few questions regarding to this statement "Mean momentum loss = 0.232 +/- 0.068 +/- 0.03 for R = 0.2 jets with 10 < pT,jet < 12 GeV/c ... for an estimated initial part length asymmetry of 0.2 fm". 

- 0.232 is the slope of <px> vs. eta. Why is it related to energy loss? Should I think of 0.232 as the average energy loss within the eta range of the measurement (|eta| < 1-R) or at a given eta? 

- Does the initial length asymmetry of 0.2 fm correspond to the slope of <x> vs. eta or <x> at a given eta? 

- If both 0.232 GeV/c and 0.2 fm are slopes, do you implicitly assume that energy loss does not depend on eta?

- You mentioned that "The impact of efficiency correction on <px> is also small like in the case of v1 as it is self normalized". What do you mean by self-normalized? I usually think of v1 as the modulation of jet yield w.r.t. the first-order even plane, so it is dimensionless and self-normalized. Should one think of <px> that way? It is not clear to me since <px> is not dimensionless. 

- You also mentioned "The pT windows are narrow, so the impact from pT dependence should also be small". There is a large smearing in jet pT due to background fluctuation. So it is not clear to me why a narrow selection in jet pT would help. I would think the other way around. While it is probably true that the impact of tracking efficiency on <px> is small due to survival bias (it is easier to find jets whose leading particles are not missing), the effect of background smearing is still there, right?

- If there is an asymmetry in pathlength, does one need to take into account possible background variation due to the asymmetry? I kind of remember this was looked into for the jet v2 measurement in Isobar. 

Best

Rongrong

On Sep 9, 2024, at 3:04 AM, Sooraj Radhakrishnan <skradhakrishnan AT lbl.gov> wrote:

Dear All,

   Please find the Preliminary request slides for the jet v1, <px> measurements here https://drupal.star.bnl.gov/STAR/system/files/JetV1PreliminaryRequest.pdf

thanks,

Sooraj