sPHENIX cold QCD topical group

["Aidala, Christine" <caidala AT bnl.gov>]

Below are minutes from today’s meeting.

 

Christine

---

 

News - Nils

----------------

This Thursday, July 12, there will be a retreat at BNL to discuss “the path forward on an EIC detector in the 1008 complex,” organized by Jamie Dunlop, bringing together people from BNL Physics, C-AD, and Instrumentation.  Nils will present the status of the EIC Detector Study Group’s efforts.

 

 

sPHENIX A_LL data impact on Delta G – Sasha Bazilevsky

----------------------------------------------------------------------------

 

Our sPHENIX Medium-Energy Nuclear Physics document from 2017 included theory curves from DSSV14 on the A_LL projection plots, but without any uncertainties.  Sasha has NLO code to calculate the theory curves for different kinematics, using different PDFs and FFs as input.  Uncertainties not available in the code for DSSV, but are available for NNPDF, allowing us to illustrate how much smaller our projected statistical uncertainties are than the current uncertainty bands on the A_LL observables.  Using NNPDF replica reweighting, can go one step further and calculate reduction in uncertainty on Delta g(x) including our projected data.  Estimate is that with sPHENIX jet A_LL data, uncertainty on Delta G integral for RHIC region of x>0.05 improves by factor of ~4—good!  100 replicas used; small number, combined with fact that only reweighting is being done, and not refitting, lead to (artificially) narrow uncertainty on Delta g(x) around x~0.2 from jets.  Some improvement expected before that from recent STAR jet and dijet data.  Suggestion to quantify the expected improvement on the truncated Delta G integral from STAR to better contextualize anticipated improvement from sPHENIX.   sPHENIX pi0 A_LL leads to improvement on truncated integral of factor >3.  Next will work on dijets.

 

-How can error band on A_LL improve to be smaller than the projected statistical uncertainties in a given pT range?  Due to the fact that each pT bin samples from wide range of x values.

 

Once study is finalized, should make the official updated plots easily available to be used in talks by collaboration members as well as Berndt Mueller.

 

 

Update on charm studies for an EIC detector based on sPHENIX – Kara Mattioli

---------------------------------------------------------------------------------------------------------

 

Ran 10k photon-gluon fusion (PGF) events, yielding ~3000 PGF to charm-anticharm pairs, then looked only at D0, D0bar decays to piK, which has been the channel for EIC charm measurements discussed most often (e.g. in EIC gluon Sivers preprint from last month, https://arxiv.org/pdf/1805.05290.pdf).  However, with D0, D0bar only ~60% of produced charm particles in PGF, and branching ratio for Kpi decay ~4%, analyzing only this channel would only measure about 2.4% of the produced charm particles assuming 100% detection efficiency.  As one source of background, piK pairs from K* produced in PGF to strange-antistrange already 10x more than the number of piK pairs from PGF to D0, D0bar. 

 

Suggestion to look at DIS 2018 talk by Yulia Furletova on charm studies for an EIC based at JLab (lower center-of-mass energies than eRHIC), https://indico.cern.ch/event/656250/contributions/2908573/attachments/1634091/2606431/DIS2018-charmJF.pdf, which discusses several channels and detection techniques.  Ultimately expect secondary vertex tagging to be important.

 

As next step will pursue fast simulations of minimum-bias e+p events to estimate realistic signal-to-background for D0, D0bar to Kpi, and include momentum smearing in invariant mass reconstruction.

 

 

 

 

From: sPHENIX-cold-QCD-l <sphenix-cold-qcd-l-bounces AT lists.bnl.gov> On Behalf Of Nils Feege
Sent: Thursday, July 5, 2018 9:56 AM
To: sphenix-cold-qcd-l AT lists.bnl.gov
Subject: [Sphenix-cold-qcd-l] Next EIC Detector Study Group / sPHENIX Cold QCD TG meeting on Monday, July 9th, evening at 8:30pm ET

 

Dear EIC and Cold QCD enthusiasts,

 

our next meeting is scheduled for

 

Monday, July 9th, 8:30pm ET.

 

The meeting is BlueJeans only (https://bluejeans.com/345777492) with the agenda evolving at https://indico.bnl.gov/event/4831. Please let us know if you have something to present.

 

We look forward to hearing you at the meeting.

 

Best,

Christine Aidala & Nils Feege

 

--

Dr. Nils Feege

Research Assistant Professor

 

SUNY at Stony Brook

Department of Physics & Astronomy

Stony Brook, NY 11794-3800

 

e-mail nils.feege AT stonybrook.edu

skype nils1920

phone +1-631-632-8710

 

www.linkedin.com/in/nilsfeege