1 / 23

Search for (3770) non-DD-bar Decays

Search for (3770) non-DD-bar Decays. Dahua Zhang (for BES Collaboration) Institute of High Energy Physics, Beijing 100039, P.R. China QWG ’ 04 October 12—15, 2004. Outline. Introduction. Search for. Evidence of. Summary. Introduction. (3770) resonance.

lynton
Download Presentation

Search for (3770) non-DD-bar Decays

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. Search for (3770) non-DD-bar Decays Dahua Zhang (for BES Collaboration) Institute of High Energy Physics, Beijing 100039, P.R. China QWG’ 04 October 12—15, 2004

  2. Outline • Introduction • Search for • Evidence of • Summary

  3. Introduction • (3770) resonance It is believed to be a mixture of and states of system Since its mass is above open charm-pair threshold and its width is two order of magnitude larger than that of , (3770) is thought to decay almost entirely to pure DD-bar. • Theoretical arguments There are some theoretical arguments about decays (3770) Lipkin pointed out that could decay to non-DD-bar final states with a large branching fraction. (3770)

  4. Study of exclusive decays of ψ(3770) Experimental study or search for some exclusive decay modes can be used to check the potential models of quarkonium and the hadronic transition mechanism of quarkonium states. To understand the long standing ρ-π puzzle in charmonium decays, the measurement of the partial width of V-P channels in ψ(3770) decay is necessary and is very interesting. Also see (hep-ph/0105327, J.L. Rosner)

  5. Theoretical prediction J.L. Rosner predicts There are some theoretical calculations about non-DD-bar decays Added all above numbers up !

  6. (3770) data sample ~18 pb-1 of data taken at 3.773 GeV ~7 pb-1 of data taken at the region from 3.768 GeV to 3.778 GeV ~8 pb-1 of data taken in the energy region from 3.665 to 3.878 GeV about 33 pb-1 of data collected around 3.773 GeV in total.

  7. Search for charmless decays of 4-prong with net charge zero Selection criteria Data taken around (3770) peak Neutral mode Charged mode

  8. Check if there are continuum production ? Normalized to the luminosity and phase space of ψ(3770) production Data taken off-resonance (@ 3.65 GeV)

  9. Charmless final states observed Resonance productions and decays QED process Observed in experiment around 3.77 GeV

  10. A detailed maximum likelihood analysis based on above observed event numbers gives is the phase difference between and giving a significance of

  11. Those yield the branching fraction and upper limit to be and partial width to be (preliminary !)

  12. Evidence for data @ around 3.773 GeV 4 good charged tacks per event are identified by combining dE/dx, TOF, BSC & Muon Search for in two different ways

  13. Evidence for (cont’d) Nominal c.m. energy of 3.773 GeV Main source of background is produced around nominal center-of-mass energy due to Breit-Wigner tail and ISR solid line dotted line Nominal c.m. energy Actual c.m. energy and productions generated at different actual energy after ISR

  14. Evidence for (cont’d) • Examine the recoil mass of Projecting the events on to the vertical scale (recoil mass of ), the evidence for is observed Due to ISR (mainly)

  15. Evidence for (cont’d) Analysis of the recoil mass 20 times large than the data and Data MC signal events out of events in total

  16. Evidence for (cont’d) analysis of the fitted dilepton masses of Open histogram is for e+e- channel, histogram in yellow is for mu+mu- channel 20 times large than the data The histogram is psi(3686), while error bars are the psi(3686) + psi(3770) signal events mainly data MC

  17. Check for other background Two photon events Analysis of 100000 two-photon Monte Carlo events, no “ ” “signal” events are found from analyzing the Monte Carlo events (~4 times larger than the data) events Analysis of 50000 events, no “ ” “signal” events are found from analyzing the Monte Carlo events (~4 times large than the data)

  18. where the D or D-bar auto-decay to all possible final states events Analysis of the MC events of 13 times large than the data, no “ ” “signal” events are found from analyzing the Monte Carlo events Generated with Lund generator (JETSET74) events Analysis of the MC events of 1.6 times large than the data, no “ ” “signal” events are found from analyzing the Monte Carlo events Analysis of the data taken at 4.03 GeV with BES-I Analysis of 22.3 pb-1of data (@4.03 GeV), no significant “ ” “signal” events are found from analyzing the Monte Carlo events

  19. Evidence for (cont’d) Signal significance The probability that the 17.8 events observed are due to a fluctuation of the events is . Number of Efficiency (for analysis of pi+pi- recoil mass) (for analysis of the fitted dilepton masses)

  20. Evidence for (cont’d) • Branching fraction • Partial width (recoil mass) (K.F.)

  21. SUMMARY BES searched for the charmless decay events of • . measured the partial width of (preliminary !) and set its upper limit to be (preliminary !) BES observed hadronic transition of to and measured the partial width to be (3770) • .

  22. 谢 谢！ Thank You！

  23. Backup slides Assuming the continuum as CLEO-c observed, then giving a significance of2.6 σ

More Related