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Recent results on non-DDbar decays of (3770) at BES

Recent results on non-DDbar decays of (3770) at BES. HaiLong Ma [For BES Collaboration] The IVIIth Rencontres de Moriond session devoted to QCD AND HIGH ENERGY HADRONIC INTERACTIONS (La Thuile, Italy) Mar.17-24 2007. Outline. Introduction. R values.

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Recent results on non-DDbar decays of (3770) at BES

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  1. Recent results on non-DDbar decays of (3770) at BES HaiLong Ma [For BES Collaboration] The IVIIth Rencontres de Moriond session devoted to QCD AND HIGH ENERGY HADRONIC INTERACTIONS(La Thuile, Italy) Mar.17-24 2007

  2. Outline • Introduction • R values • BF[(3770) → D0D0,D+D-,DD and non-DD] • Parameters of (2S) and (3770) • Search for charmless decays of (3770) • Summary

  3. Introduction R is one of the most fundamental quantities in particle physics, which counts directly the charges, the flavors and the colors of quarks involved. R(s) values are important for vacuum polarization correction, which plays an important role in the precision test of the Standard Model; evaluation of the electromagnetic coupling at the Z mass scale, . determination of of the muon. evaluation of understanding of (3770) non-DD decays and others……

  4. Introduction (3770)is thought to decay almost entirely to pure DDbar, but there is large discrepancy between and Cross section at peak (PDG04 parameters) before BES-II & CLEO-c (Mark-III) Long-standing puzzle of (3770) production and decays • Simultaneously measusing both and • Precisely measuring the energy dependent cross sections for both inclusive hadrons and DDbar events production simutanmeously, directly measure • and • Search for some exclusive non-DDbar decays BES made several fine cross section scans covering both the (3686) and (3770) to measure the resonance parameters, branching fractions and search for non-DD decays …

  5. BESII (3770) data sample of about 33 pb-1 ~17.3 pb-1 data taken at 3.773 GeV ~7 pb-1 data taken at the region from 3.768 GeV to 3.778 GeV during Mar. 2003 ~8 pb-1 data taken in the energy region from 3.665 to 3.878 GeV during Dec. 2003 ~6.5 pb-1 of data collected at 3.650 GeV ~1.0 pb-1 of data collected at 3.665 GeV Largest sample from CLEO-c by Summer, 2005

  6. Measurements of the R values at 3.650, 3.6648 and 3.773 GeV PLB641(2006)145 Obtaining by fitting to the R values measured by BES in the range from 2.0 to 3.0 GeV

  7. Measurements of Rhad, Ruds(c) and Ruds(c)+(3770)in the range from 3.650 to 3.872 GeV efficiency Dec. 2003 data set ISR factor Table. Systematic uncertainties in the determination of R values PRL 97(2006)262001

  8. Determination of BF[(3770) → D0D0,D+D-,DD and non-DD] with the measured R values at 3.650, 3.6648 and 3.773 GeV Single tag method PLB 603(2004)130 Some systematic uncertainties can be canceled out Radiative correction factor Radiative correction factor obtained based on new (3770)resonance parameters measured by BES-II, hep/0605107. PLB641(2006)145

  9. Line shape of the cross sections for hadron and DD-bar production Inclusive hadrons Inclusive hadrons Inclusive hadrons PRL97(2006)121801 Simultaneously.fitting to the inclusive hadron and the DD-bar production cross sections Mar. 2003 data set • Branching fractions

  10. Comparison of (3770) Resonance Parameters Mar. 2003 data set PRL 97 (2006) 121801

  11. Comparison of (3686) Resonance Parameters The measured partial width is consistent with PDG06 partial widthof (3686). Mar. 2003 data set PRL97(2006)121801 PDG06

  12. Precision measurements of the mass, total and leptonic widths of (3770) with the measured R values in the range from 3.650 to 3.872 GeV Dec. 2003 data set Partial width Preliminary! hep-ex/0612056

  13. Leptonic branching fraction PRL97(2006)121801 (0.98+/-0.06) Preliminary! hep-ex/0612056 PRL97(2006)121801 PRD21(1980)2716

  14. Search for charmless decays of (3770) International Journal of Modern Physics A, Vol 21 No. 27 (2006) 5416 Observed Cross Sections No obvious cross section discrepancy at the two energy points is observed. However, to extract the non-DD-bar branching fractions of (3770) decays, one needs to consider the interference between the two amplitudes of the continuum and the resonances, and to consider the difference of ISR & vacuum polarization corrections at two energy points. Preliminary

  15. Summary • BES measured R values at the three energy points and in the energy region between 3.650 and 3.872 GeV • BES firstly measured the branching frations for non-DDbar decays of (3770) using two different data sample and two different methods • BES more precisely measured the parameters of the (2S) and (3770) resonances • BES searched for charmless decays of (3770) Thank You！

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