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Changyi Zhou ( McGill University) Sergei Chekanov (Second analysis)

Changyi Zhou ( McGill University) Sergei Chekanov (Second analysis) QCD/HFS Weekly Meetings September 20, 2007. Outline. Analysis motivations Previous publications and results Observation principle Data sample and selection K 0 s K 0 s spectra with fits

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Changyi Zhou ( McGill University) Sergei Chekanov (Second analysis)

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  1. Changyi Zhou ( McGill University) Sergei Chekanov (Second analysis) QCD/HFS Weekly Meetings September 20, 2007

  2. Outline • Analysis motivations • Previous publications and results • Observation principle • Data sample and selection • K0sK0s spectra with fits with DIS selection in second analysis • Systematic uncertainty checks • Result comparison • Summary of plots and table for preliminary • Conclusion and outlook

  3. Motivations • The Standard Model explains the existence of hadrons well. • The Standard Model allows for the existence of particles made by gluons. • A gluon carries both a color and an anti-color. • Either two or three gluons may confine together as color singlet GLUEBALLs Examples of glueballs

  4. Motivations (Cont.) • The K0sK0s system is expected to couple to scalar and tensor glueballs Ks: has S=L=0, P=-1, C=+1 KsKs: has P=+1, C=+1  J = even Question: What is the mixing fraction?

  5. Motivations (Cont.)

  6. Previous Publications • “Observation of K0(s) K0(s) resonances in deep inelastic scattering at HERA” (ZEUS) (AIP Conf.Proc.717:105-109, 2004 /e-Print Archive: hep-ex/0310002 ) ~3 δ for f0(1710) But the width is a factor of 4 smaller than in PDG

  7. Previous Publications • “K0sK0s Final State and Glueball Searches and Lambda-Lambdabar Production in Two-Photon Collisions in L3 at LEP”Published in *Ambleside 2000, Structure and interactions of the photon* 366-373 / e-Print Archive: hep-ex/0010030 ~4δ for fJ(1710)

  8. pπ+ pk1 π+ Collinearity Angle pπ- Pri. Vtx K0s π- IP Sec. Vtx pπ+ Cos(kk) Two V0 candidates π+ K0s Decay Length DxyDz pk2 pπ- π-

  9. DATA Sample and Event Selection • HERA I data: Around 0.5 fb-1 in total • HERA II data: All Data OR DIS event (≈10%)

  10. Event Selection (cont.) < W > ≈ 200 (GeV)

  11. K0s mass spectrum for K0sK0s events Large Statistics Clean Sample (Tails have been chopped online to reduce data sample size)

  12. 96-07 data PHP+DIS Clear evidence for 3 states Inclusion of 3rd Breit-Wigner to describe 1710 region is necessary to improve χ2

  13. 96-07 data PHP+DIS Perfect fit (χ2/ndf≈ 1.1 ) Statistical significance of f(1710) ≈ 5084/312 ≈ 16 Sigmas

  14. HERAII The deep between f(1270) and f(1525) could be to the interference between the two states. Amplitudes with an arbitrary phase need be added. Noted by D. Saxon / M. Derrick

  15. HERAI 2004 2005 2007p 2006p 2006e

  16. HERAII DIS Sample DIS ≈ 10% of all

  17. Second Analysis S. Chekanov No 1710 region fit With 1710 region fit

  18. Systematic Uncertainties

  19. Comparison

  20. Request for preliminary

  21. Request for preliminary

  22. Request for preliminary

  23. Conclusion • All three resonance states are measured and established with all ZEUS statistics (0.5 fb-1) • Clear evidence for f0(1710) state with about 16 sigmas  Note: previous measurement in colliding experiments e.g. ZEUS and L3 had 3-4δ • No state heavier than f0(1710) was observed • Good agreement with the second analysis • Very competitive measurements on peak position and width for f’2(1525) and f0(1710) • Good agreement with the PDG values

  24. Outlook To do: • Produce a draft by the end of this year • Enriching the analysis webpage: http://www-zeus.desy.de/~czhou/work/newpage/newK0sK0s.html • Write a thesis • ..

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