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Recent progress on h c and  cJ at BESIII

Recent progress on h c and  cJ at BESIII. Wang Zhiyong (for BESIII Collaboration) Institute of High Energy Physics, Beijing, China. La Thuile 2010, Mar. 13-20, 2010, Italy. Outline. Introduction of BEPCII & BESIII Observation of h c Measurement of Br(  c0,2 PP)(P=  0 ,  )

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Recent progress on h c and  cJ at BESIII

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  1. Recent progress on hc and cJ at BESIII Wang Zhiyong (for BESIII Collaboration) Institute of High Energy Physics, Beijing, China La Thuile 2010, Mar. 13-20, 2010, Italy

  2. Outline • Introduction of BEPCII & BESIII • Observation of hc • Measurement of Br(c0,2PP)(P=0,) • Observation of cJVV. • Summary

  3. Beijing Electron Positron Collider II (BEPCII)@ IHEP • Beijing Spectronmeter • BESI: 1989 - 1998 • BESII: 1999 - 2004 • L ~ 51030cm-2s-1 @ J/y • Ebeam ~ 1- 2.5GeV • BESIII: 2008 – • Physics run from • March 2009, • ~110M y(2S), ~220M J/y • L~3.21032cm-2s-1 @y(3770) • ~30% of designed value BESIII Linac BESIII BSRF Storage ring • Energy spread: • 5.16×10-4 • No. of bunches: • 93 • Bunch length: • 1.5 cm • Total current: • 0.91 A • BEPCII • Beam energy: • 1.0-2.3 GeV • Luminosity: • 1×1033 cm-2s-1 • Optimum energy: • 1.89 GeV

  4. BESIII @ BEPCII EMC MDC • MDC: s(pT)/pT = 0.32%0.37% @1GeV dE/dxreso < 6% • TOF: 80 ps (for bhabha, barrel) • EMC: s(E)/E = 2.3%×√E • MUC: 9 layers for barrel, 8 layers for endcap MDC TOF BESIII

  5. Physics potential at BESIII IJMP A V24 No 1 (2009) supp • Light hadron spectroscopy • Full spectra: normal & exotic hadrons QCD • How quarks form a hadron? Non-pQCD • Charm physics • CKM matrix elements SM & beyond • DD mixing & CPV SM & beyond • Charmonium physics • Spectroscopy & transition pQCD & non-pQCD • New states above open charm thresholds exotic hadrons ? • pQCD: rp puzzle a probe to non-pQCD or ? • Tau physics & QCD • Precision measurement of the tau mass & R value • Search for rare & forbidden decays • The physics window is precision charm physics & the search for new physics. • High statistics: high luminosity machine + high quality detector • Small systematic error: high quality detector.

  6. Milestones of BESIII • Peak Lumi. @ May 2009: 3.2×1032cm-2s-1 • ×5 CESRc @ y’’ • ×30 BEPCI April 30, 2008: Move the BESIII to IP July 19, 2008: First e+e- collision event April 14, 2009: ~110M y(2S) events collected (×4 CLEOc) May 30, 2009: 42 pb-1 at continuum(3.65 GeV) collected July 28, 2009: ~220M J/y events collected (×4 BESII)

  7. hc(1P1) in charmonium family - • The cc singlet state hc was predicted • by theory long time ago. • In 2008, hc was observed by CLEO_c • in charmonium decays • hc can only be observed in the process • of y(2S)p0hc • the main decay mode of hc: • the E1 transition hcghc. • CLEO-c first measurement of hc • y(2S)p0hc,hcghc, E1-tagged PRD 72, 092004 (2005) CLEO CLEO: PRL 101, 182003(2008) B1= Br(0hc) B2= Br (hc c)

  8. E1-tagged y(2S)p0hc, hcghc at BESIII • Select E1-photon to tag hc • A fit of Double Gaussian signal + sideband BG yield: Significance = 18.6, N(hc)=3679±319 arxiv:1002.0501 arxiv:1002.0501 firstly CLEO: PRL 101, 182003(2008)

  9. hcMeasurement ininclusivey’p0hc (Without E1 tagged) Inclusive p0 recoil mass spectrum Significance = 9.5, N(hc)=10353±1097 arxiv:1002.0501 arxiv:1002.0501 • Select inclusive p0 • A fit of Double Guassian signal + 4th poly. BG yield: Combined inclusive & E1-photon-tagged spectrum, thefirstmeasurement: Br(’0hc)=(8.4±1.3±1.0)10-4 Br(hcc) =(54.3±6.7±5.2)% Theoretical predictions of branching ratios: Br(y’p0hc) = (0.4-1.3)×10-4 Br(hcghc) = 48% (NRQCD) Br(hcghc) = 88% (PQCD) (Y.P.Kuang, PRD 65,094024 (2002)) Br(hcghc) = 38% (S. Godfrey & J.Rosner,PRD 66,014012(2002)) BESIII: arxiv:1002.0501,accepted by PRL

  10. BESIII BESIII Study ofc0,200,( , 0 ) ’00 Nc0: 17443±167 Nc2: 4516±80 • Radiative decay of charmonium to 00, are interesting channels for glueball searches. • Exclusive decays of ccJ are good laboratory to test the color-octet mechanism in P-wave charmonium decays. • BR of ccJtohh, h’h, h’h’ determine the ratio of contributions from SOZI and DOZI graphs. arxiv:1001.5360 ’ Nc0: 2132±60 Nc2: 386±25 arxiv:1001.5360 arxiv:1001.5360, accepted by PRD

  11. Study ofcVV, V=,  • ccJ ff and ccJww Singly OZI suppressed • cc1 ff and cc1ww is only allowed for L=2, suppressed ? • ccJ fw is doubly OZI suppressed, not measured yet y(2S)gww @ BESII y(2S)gff @ BESII 1 1 PLB 642,197(2006) PLB 630,7 (2005)

  12. Study ofcJ BESIII preliminary Two f sideband Branching fraction the first measurement of cc1ff

  13. Study ofcJ BESIII preliminary the first measurement of cc1ww • ww signals are clearly observed • backgrounds and non-resonance contributions are studied with two-w sidebands and continuum data, very low.

  14. mK+K- (GeV) mp+p-p0 (GeV) First observation of cJ mKK versus m+-0 for Data • wf signals are clearly observed • backgrounds and contributions from non-resonances are studied with w & f sidebands, and continuum data. BESIII preliminary • ccJ  fw OZI doubly suppressed • surprisingly the doubly suppressed decay is first observed!

  15. Summary • Observation of hc from (2S)0hc: • first measurement: absolute Br((2S)0hc) & Br(hcc) • (hc); • Observation of cJVV • cJ, , ; • First observation: cJ; • First observation: c1 ,; • Measurement of Br(c0,200) ,Br(c0,2) • More exciting results are coming. THANKS !

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