preliminary plots for QM2018

Other plots are coming soon...

Proceeding for QM2018 :
https://drupal.star.bnl.gov/STAR/system/files/raoyama_QM2018_proceeding_revised.pdf

Systematic uncertainties :
-vn
--|DCAglobal| upper limit : 1cm (default), 0.5cm (tight), 2.0cm (loose)
--nHitsFit lower limit : 20 (default), 25 (tight), 15 (loose)
--method : two-particle correlatiion method and EP method

-Di-hadron correlation
--MC simulation for determination of BG shape
---EP resolution difference
---vn \pm 1\sigma
--ZYAM : 4points (default), 6points (tight), 2points (loose)
--unfolding : fitting method, iteration method
---iteration method : smoothing parameter