STAR HardProbes PWG

[David Stewart <0ds.johnny AT gmail.com>]

Dear PWG and convenors,

For some years, STAR used 5% uncertainty on track reconstruction uncertainty, but that has decreased somewhat. STAR's recent jet mass paper used 4% (linked here) used 4%, citing a prior star spin paper (linked here) for pp collisions. Some years ago in Au+Au collisions, our h+jet Au+Au paper (AN linked here) used 5%. The current code and manuscript of our p+Au jet paper (paper's drupol page here) uses 4.5%, as had been suggested by L. Huo's thesis. If I am not mistaken, there is ongoing discussion how much lower to make it. In any case, I don't have a solid reference. Our GPC chair, Rongrong, has requested that we get a value officially approved by the PWG. For a little context, the p+Au events are much closer in system size to pp than to Au+Au. Our paper draft shows that in low EA events the track density is approximately pp-like, and increase to about twice the highest EA events. Whatever the value we do agree on, 5% wouldn't hurt this paper, but we also don't want to be unnecessarily conservative.

Thanks,

Dave

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David Stewart

Postdoctoral Fellow | Department of Physics, Wayne State UniversityI