d+Au ridge: More Peripheral, More Central with Primary Tracks

Updated on Tue, 2014-08-26 22:57. Originally created by yili on 2014-08-26 22:53.

Motivation:

In d+Au Ridge study, 0-20% and 40-100% have been analyzed for central and peripheral. See drupal.star.bnl.gov/STAR/blog/yili/dau-ridge-global-tracks-inclusive-charge.

Cent-R*Peri method has been discussed and two double-ridge is found.

Here we'd like to go to more peripheral 60-100% and more central 0-10% to investigate whether conclusion will be affected. Or in another word, if there is flow/ridge in 40-100%, how large the contribution will affect the subtraction result.

For global track result, see drupal.star.bnl.gov/STAR/blog/yili/dau-ridge-more-peripheral-more-central

Here the primary track results are presented.

Method:

Dihadron correlation.

Fit near-side Δη with Gaussian + Pedestal. Fit parameters Y for Gaussian area, σ for Gaussian width, C for pedesta. For both central and peripheral.

1. Near-side jet yield central over peripheral ratio R.

2. Cent - R x Peri for dihadron correlation

Primary tracks.

Data set:

Run3

|Vz| < 50 cm
nHitsFit > 25 points for TPC
nHitsFit > 5 points for FTPC
nHitsFit/nHitsPoss >= 51%
globa dca < 3 cm
|eta|<1 for TPC
2.8<|eta|<3.8 for FTPC
1<pT<3 GeV/c

Primary tracks

Results:

1. Near-side jet Δη distribution

Both trigger and associated particles in TPC

FTPC centrality

R = Y^cent / Y^peri = 1.404