Embedding request: https://drupal.star.bnl.gov/STAR/starsimrequests/2023/Feb/15/pi-K-p-FXT-run-19
Pi/K/p: 0<pT<2.5 GeV/c, -2.4<η<0

Embedding QA:
Event level selection: 
sqrt( ((vx+0.423)*(vx+0.423)) + (vy+1.958)*(vy+1.958) )< 2 cm
|Vz-200|<2 cm

Efficiency (do not add pT/rapidity weighting):
Track quality cut: gDca<3 cm && nHitsFit>15 && nHitsFit/nHitsPoss>0.52
(updated on April 12,2023 for -2.4<eta<-2)
pion+: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_pip.pdf
pion-:https://drupal.star.bnl.gov/STAR/system/files/plots_eff_pim.pdf
K+ : https://drupal.star.bnl.gov/STAR/system/files/plots_eff_kp.pdf
K-: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_km.pdf
proton: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_p.pdf
anti-proton: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_ap.pdf

pion plus, reconstructed tracks: nHitsFit vs eta

In Au+Au 19GeV electron embedding, some issue with nHitsDedx at pT=0.1 GeV.
https://drupal.star.bnl.gov/STAR/system/files/low_pt_electron_Yiding_0.pdf
Such issue is not very obvious in FXT embedding mostly because the acceptance at 0.1 GeV is not very good. But still see a structure in pion minus. 
(right plot: nHitsDedx vs pT at nHitsFit>20 && gDca<3cm)
To look into details, below is efficiency plots with cut "nHitsdEdx>10 && gDca <3 && nHitsFit>20 && nHitsFit/nHitsPoss>0.52"
kaon: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_kp_ndedx.pdf
proton: https://drupal.star.bnl.gov/STAR/system/files/plots_eff_p_ndedx.pdf
pion:  https://drupal.star.bnl.gov/STAR/system/files/plots_eff_pim_ndedx.pdf
For proton and kaon, no obvious issue but for pion, similar structure appears at eta>-1.5.

Conclusion: we do not observe obvious centrality dependence for single particle tracking efficiency.

Comparison between gDca and nHitsFit, only primary tracks are selected.
(1) particles are selected by TPC, no pt/rapidity weight
PID: for pion and kaon,  |nSigma-1.5|<2 (1.5 is due to the offset in calibration). For proton, selected by recalibrated dE/dx

gDca distribution:
pion+: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVpip_gDca.pdf
pion-: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVpim_ gDca_2 .pdf
proton: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVp_gDca.pdf
anti-proton: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVap_gDca.pdf
kaon samples suffer large contaminations from other particles, so do not show here.
A capture of pi- gDca:

nHitsFit distribution:
pion+: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVpip_nhits.pdf
pion-: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVpim_nhits_0.pdf (Pretty beautiful match between data and embedding for pion minus)
proton: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVp_nhits.pdf
anti-proton: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVap_nhits.pdf 
A capture of pi- nHits

Conclusion: 
Overall the embedding samples are able to describe data. Although some pT bins may suffer from contamination of other hadrons.

(2) particles are selected by TOF&TPC, no pt/rapidity weight. PID is cleaner. But Tracks required TOF-match maybe limited by TOF acceptance
Also TOF tracks tend to select higher nHitsFit tracks. So these are just as a reference.
(nHits plots started at page 216)
pion+: https://drupal.star.bnl.gov/STAR/system/files/plots_3.2GeVpip_wtof.pdf

Reference:
Well known FXT set-ups: