Quarikonia Study

1. Motivation of Quarkonia (qqbar -> +mu -mu, J/psi, Upsilon family) Study at CMS (Fig. 1)

- Quarkonia's step-wise suppression at high pt region is the one of most direct probes of QGP (Quark-gluon-plasma)

- J/Psi's suppression is already observed in SPS and RHIC.

- So, how about it in CMS ? (there could be more huge suppression or enhanced regeneration ?) and how about Upsilon ?

What is more benefits of CMS than other experiments ?

- It can make plasma hotter, longer-lived than RHIC (it can be easy to dissolute the particles which has large binding energy)

- provide good circumstances to produce Quarkonia highly

- high luminosities : 5*10^26 cm^-2 s^-1 (increase events rate)

- high gluon density at low-x, (the almost particles of heavy-flavor quarks is made by gluon-gluon fusion)

- New possibility of Upsilon family (Y, Y', Y'')

2. Quarkonia Generation with HYJET

2nd HYDJET production information

* decache location : /pnfs/cmsaf.mit.edu/t2bat/cms/store/user/davidlw/HYDJET_GEN_X2_MB_4.0TeV/HYDJET_GEN_X2_MB_4.0TeV/545444c24aba01a433ce34e4c379212c/

* 100k production by Wei, including more quarkonia

Analysis of quarkonia with CMSSW at CMSSW_2_1_x

- use 'HydQuarkoniaAnalyzer.cc'

1) pT distributions of J/psis

- the flat around 5 -10 GeV?/c doesn't feed down. This unexpected effect seems to be caused by the cases that the mother is J/psis themselves, chi_cs and color octet state. It is neccessary to check generation situation.

- pT distribution of Upsilon from 100k hydjet minbias event.

2) pT distributions of muons from Kaons, B meson and J/psis

3) Dimuon mass continuum with muon combination

- use 'MuonCombiAnalyzer.cc' - in order to look into clear signal, the study was done separately 0-1 GeV?/c^2, 2 - 4 GeV?/c^2, 0 - 10 GeV?/c^2.

Mass range 0 - 10 GeV?/c^2

Mass range 0 - 1 GeV?/c^2

Mass range 2 - 4 GeV?/c^2

-- DongHoMoon - 27 Apr 2009