VTX Analysis Status and Future Directions
"Explore the latest findings on bottom/charm electron suppression at RHIC, ongoing VTX analyses for Run14AuAu and Run15pp, along with crucial updates and challenges in the current analysis process."
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Presentation Transcript
VTX analysis Status Takashi Hachiya
Introduction One year from the first VTX publication (PPG182) First result for bottom/charm electrons from run11 VTX analysis is published just 1 year ago First observation of bottom suppression at RHIC energy Less suppression of bottoms than charms Analysis method was established DCA analysis Unfolding Run11AuAu We are focusing on Run14AuAu and Run15pp analyses 1/4 of full data is available for analysis All data is about 12B events w/ |Z|<10cm Preliminary result of b/c was shown at QM17 Min. Bias and 0-10% central events Difference of the suppression for bottom and charm is clearer Run14AuAu People Run14AuAu : Kazuya, Gaku, Yosuke, Takashi Run15pp : Tim(Iowa), Javier(Colorado), Gaku
Going forward to publication of Bottom/charm analysis with VTX Target date Run14AuAu : End of Dec. 2017 to be submitted to the journal Run15pp : End of summary 2017 when PPG is formed Issues for run14 AuAu analysis 1. DST production needs to be finished by then Event mis-alignment problem can be fixed Efficiency is increased with 30-40% by fixing the clustering bug at the strip detector (we want) Target date has priority than using all the data We can update the results later when publishing HF v2 or summary paper 2. Analysis methods several issues Peripheral analysis (should be checked) Self-bias problem new method developed for pp (next page) Invariant yield (small) Backgrounds (small) Unfolding (large)
Sys. Errors in current run14 analysis Contributors Unfolding Regularization (prior) Data analysis High mult. BG (low pT) Statistics (high pT) Spectra (high pT)
Spectra Yield is calculated using the bootstrap method Kazuya and Gaku are working for Au+Au and pp MB looks OK but 0-10% is worse
High Multiplicity BG in DCA Chg Had DCA FG BG(rotation) A peak at DCA~0 for BG was newly found in the run14 preliminary analysis Peak : Series of clusters made by a track can be picked up Broad Tail: random association with independent clusters The peak is confirmed by Yosuke s simulation Multi-particle simulation was performed Shoulder
Prior in unfolding (mod. Hagedron as default) Prior is an assumption of B/D yield as input 1. Initial point of MCMC sampling 2. Reference of the smoothness If the pT shape of the result is similar with the prior, likelihood is large This constraint is too strong and should be updated Unfolding can affected by the choice of prior
Event realignment Pixel had instability issue of the hit rate, which cannot be understood for long time. Shaper Amp. 4 evts buf Hit rate SR Event hit may be in the next 4 events
Event realignment Pixel had instability issue of the hit rate, which cannot be understood for long time. Shaper Amp. 4 evts buf Hit rate SR hit may be in the next 4 events
Event realignment Pixel had instability issue of the hit rate, which cannot be understood for long time. Shaper Amp. 4 evts buf Hit rate SR hit may be in the next 4 events Mis-alignment problem was basically fixed There is some spikes Side effect to fix the problem is the reconstruction time and effort Multiple path is necessary: 1. Make the hit DST for each PRDF 2. Mix these hit DST s to realign the event 3. Run the standard reconstruction using the re-aligned DST Kazuya and Yosuke agreed to help the production with Zack and computing team
Primary Vertex Problem Primary vertex is important to calculate DCA Primary Vertex is calculated using the standalone track Issue: the calculated primary vertex, then DCA can be biased for the low multiplicity such as pp and peripheral AuAu The track of interest is used for the vertex calculation Our approach : new primary vertex calculation 1. Calculate primary vertex without the track of interest 2. Combine the primary vertex and beam center with a weight of their resolution Res(Beam center) = ~110um Res(PrimVertex) = 50um ~ , depending on the Ntrack Test with simulation The method works well Can/should be used for pp and peripheral AuAu B->e simulation
Summary Problems/Issues were fixed Analyses are in progress P+p analysis is going Gaku is working on p+p analysis, especially for invariant yield as well Concerns It takes long time for the DST production Keep watching how the production goes
