1 / 17

f meson production at 200 GeV from STAR

f meson production at 200 GeV from STAR. Jingguo Ma University of California, Los Angeles for the STAR collaboration. I. Motivations II. Preliminary Results III. Summary. Motivations. m ~ 1019 MeV/c 2  ~ 4.45 MeV/c 2 c t ~ 41 fm Vector meson quark content : s, sbar

Télécharger la présentation

f meson production at 200 GeV from STAR

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. f meson production at 200 GeV from STAR Jingguo Ma University of California, Los Angeles for the STAR collaboration I. Motivations II. Preliminary Results III. Summary

  2. Motivations • m ~ 1019 MeV/c2 •  ~ 4.45 MeV/c2 • ct ~ 41 fm • Vector meson • quark content : s, sbar • Decay mode: •   K+ K- (49.2%) • Maybe phi can be a good probe of QGP • • OZI rule suppression • • small cross section for scattering • with nonstrange hadrons • Information from earlier time? • Sensitive to early flow? • Chiral Symmetry Restoration: • mass shift, width broadening? • Production mechanism: • ggg ->  • s sbar ->  • K+K- -> 

  3. Data set Number of charged particles AuAu collisions: MinBias data 2.1M events Central data(top 5%) 0.5M events pp collisions: 4M events

  4. K+K- pair invariant mass background subtracted AuAu collisions Mearsured Mass=1019 MeV/c2,FWHM=7.80.5 MeV/c2

  5. K+K- pair invariant mass Misidentified Ks Phi background subtracted pp collisions Measured Mass=1019 MeV/c2, FWHM=7.10.3 MeV/c2

  6. Preliminary results • |y|<0.5; • Measured Pt range: 0.4GeV~3.9GeV; • Exponential function fit well to the spectra of AuAu collisions; • Spectra from pp collisions fit well to a power law function; •  Statistical errors only. STAR preliminary Fit functions: AuAu: mt exponential pp: pt power law

  7. Preliminary results STAR preliminary • AuAu collisions Spectra in different rapidity bins; • Exponential function fit to the spectra; •  Statistical errors only.

  8. dN/dy vs. nCharge STAR preliminary • dN/dy increases • linearly with nCharge; • • Statistical errors only.

  9. Boost invariance STAR preliminary • Boost invariance in |y|<1.0; • • Statistical errors only.

  10. Phi/K- STAR preliminary • N()/K- independent of collision centralities.

  11. Energy dependence • Data points are from most central heavy ion collisions; • N()/N(h-) increase with beam energy—follow the same trend as the K- production; • Statistical errors only. STAR preliminary AGS SPS RHIC

  12. Energy dependence STAR preliminary • Data points are from most central heavy ion collisions; • N()/N(K-) independent of beam energy. AGS SPS RHIC

  13. <pT> centrality dependence 1)p, K, p mean transverse momentum <pT> increase in more central collisions; 2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow; 1)p, K, p mean transverse momentum <pT> increase in more central collisions; 2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow; 3)f-meson seems flow differently. Star preliminary

  14. <pT> vs. particle mass 110MeV,<>=0.55 170MeV,<>=0.0 110MeV,<>=0.0 Lines are from thermal model calculation. Again, <pT> of f-meson does not change with centrality. f-meson may give earlier partonic information!

  15. Summary • 200 GeV f meson production from both AuAu and pp collisions is measured; • AuAu spectra fit well to an exponential function, while pp results fit well to a power law function; • dN/dy of f scales linearly with number of charged particles; • dN/dy and inverse slope measurement shows boost invariance for f within |y|<1.0; • In AuAu collisions, within the measured centrality range, the shape of the transverse momentum distribution weakly depends on the centrality – absence of significant hadronic re-scatterings for phi?

  16. Phi/nCharge

  17. 0-5% 0-10% 10-30% 30-50% 50-80% pp Measured Mass

More Related