1 / 17

LL spin correlations and spin selected HBT

LL spin correlations and spin selected HBT. Fei Du, Sandweiss’ group, Yale. Outline: Lambda and its decay Spin correlations Spin selected HBT. L and its decay. L (uds) m = 1115.683 ± 0.006 MeV c t = 7.9 cm Asymmetry in decay. L detection at STAR.

colby
Download Presentation

LL spin correlations and spin selected HBT

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. LL spin correlations and spin selected HBT Fei Du, Sandweiss’ group, Yale • Outline: • Lambda and its decay • Spin correlations • Spin selected HBT DOE review, 09/15/2003

  2. L and its decay L(uds) • m = 1115.683 ± 0.006 MeV • ct = 7.9 cm Asymmetry in decay DOE review, 09/15/2003

  3. L detection at STAR Topological method: pair up decay products (p and p-) with geometry and invariant mass cuts Preliminary DOE review, 09/15/2003

  4. How to find out the L spin Two transformations: • 1st: transform to the CMS of the di-L pair • 2nd: transform each proton to the rest frame of its parent L. • Take the proton momentum direction as an indicator of the L spin direction. DOE review, 09/15/2003

  5. LL spin correlations • Spin correlation at low : due to Fermi-Dirac statistics. • For LL system, at low Q, s-wave state (l=0) dominates (symmetrical space wavefunction), thus total spin S = 0. (↑↓-↓↑) • Spins are anti-aligned. DOE review, 09/15/2003

  6. Complication I – Q is never 0 • Finite Q→ source radius DOE review, 09/15/2003

  7. Complication II – spin direction is not perfectly measured Calculation done by G. Alexander et. al.: Use of Spin-Correlations to Study Low Energy LL and LL Space Symmetries and Resonances, Phys. Lett. B352:162, 1995 DOE review, 09/15/2003

  8. Spin correlation golden formula DOE review, 09/15/2003

  9. ALEPH data DOE review, 09/15/2003

  10. Preliminary Preliminary Preliminary Preliminary Preliminary Preliminary DOE review, 09/15/2003

  11. Fit dN/dy to 1 + ky Preliminary DOE review, 09/15/2003

  12. HBT (Bose-Einstein correlation) DOE review, 09/15/2003

  13. Aligned spins: Anti-aligned spins: HBT (Fermi-Dirac correlation) DOE review, 09/15/2003

  14. Better treatment DOE review, 09/15/2003

  15. HBT with spin selection DOE review, 09/15/2003

  16. Preliminary Preliminary Preliminary DOE review, 09/15/2003

  17. Outlook • With next year’s data (~ 20x more statistics than shown in the plots here), things will become much clearer. • Also we can use tighter cut on spin alignment with more statistics. DOE review, 09/15/2003

More Related