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e + e -  J/ (cc) res Full e + e - J/  c reconstruction Angular analysis

e + e -  J/ (cc) res Full e + e - J/  c reconstruction Angular analysis e + e -  (2S) (cc) res Recent search: strong evidence for a new charmonium state X(3940) in e + e -  J/ X(3940). P.Pakhlov (ITEP, Moscow) (for Belle collaboration). Double cc production.

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e + e -  J/ (cc) res Full e + e - J/  c reconstruction Angular analysis

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  1. e+e- J/ (cc)res Full e+ e- J/ c reconstruction Angular analysis e+e- (2S) (cc)res Recent search: strong evidence for a new charmonium state X(3940) in e+e- J/ X(3940) P.Pakhlov (ITEP, Moscow) (for Belle collaboration) ICHEP’04 Beijing, China

  2. Double cc production Belle observed e+ e-J/cc, where additional cc pair fragments into either charmonium or charmed mesons PRL 89, p.142001 (2002) • (e+e-→ J/c)  10   theory calculated for single virtual photon diagram • Double virtual photon annihilation (Bodwin, Lee, Braaten): (e+e-→J/J/ )  (e+e-→J/c) in this case! • Peaks at Mrecoil areglueballs? (Brodsky, Goldhaber, Lee + Dulat, Hagiwara, Lin) • This analysis is described in hep/ex-0407009 (accepted for PRD-RC) P.Pakhlov (ITEP, Moscow)

  3. e+e-→ J/(cc)res with L=155 fb-1 • Study recoil mass against J/: Mrecoil((Ecms –EJ/)2 –PJ/2)½ • Include all known charmonium states: c, J/, c0, c1, c2, c’, (2S) • Yields for J/, c1, c2, (2S) ~ 0  set UL c, c0, c’ confirmed J/, c1, c2, (2S) not seen P.Pakhlov (ITEP, Moscow)

  4. Verify Mrecoil scale Recoil mass is subtle: momentum scale bias may result into large M2recoil bias  misinterpretation of recoil system nature… • Check Mrecoil using the data • Use radiative return e+ e- (2S)  for calibration. very clean sample (>99% purity) • Fit to M2recoil ((2S)) with free peak position • No shift in the data:  M2recoil((2S)) < 0.025 GeV2   Mrecoil(J/) < 3 MeV M2recoil ((2S)) Gev2/c4 P.Pakhlov (ITEP, Moscow)

  5. e+e-→ J/c full reconstruction Data • cKsK, KKKK • Require: EJ/+E c ~Ecms • 3 events are found in the data (>4) • 2.6 events are expected from MC based on Mrecoil fit yield MC No ISR ISR >10MeV P.Pakhlov (ITEP, Moscow)

  6. Angular analysis Fit Mrecoil(J/) in bins of J/ production and helicity angles P.Pakhlov (ITEP, Moscow)

  7. Angular analysis • Correct on efficiency • Fit with ~(1+cos2) • production and helicity angles separately • simulteneously: prod=hel P.Pakhlov (ITEP, Moscow)

  8. e+e-→(2S)(cc)res • Similar analysis for reconstructed (2S)J/ • Fit to Mrecoil ((2S)) spectrum: • 5.3  observation of sum of c, c0, c’ Similar tendency: c, c0, c’ seen… J/, c1, c2, (2S) not seen P.Pakhlov (ITEP, Moscow)

  9. X-sections • For efficiency assume: prod=hel=+1 for  prod=hel=-1 for  • Calculate Borncross-sections: • Find the fraction of events with EISR<Ecutoff =10 MeV from MC • No correction for the cut on charged multiplicity: the result is EISR<Ecutoff =10 MeV EISR>Ecutoff =10 MeV  * BR (recoil charmonium  >2charged) fb P.Pakhlov (ITEP, Moscow)

  10. Recent update L=101 fb-1 2002 Whole Belle data set collected by July 2004 L=287 fb-1 2003 L=155 fb-1 P.Pakhlov (ITEP, Moscow)

  11. Evidence for new charmonium • The reconstruction and selection procedure is not changed since the first Belle paper • Extend the studied region • No signal of X(3872) • Significant peak at M=3.9400.011 GeV/c2 • N=14833 (4.5) • The width is surprisingly narrow <~ resolution (= 32 MeV) X(3872) P.Pakhlov (ITEP, Moscow)

  12. Search for X(3940)  DD(*) • Idea: Reconstruct J/ and one D; Look for the second D(*) in the event at recoil mass against reconstructed (J/ D) • Use only the cleanest D0K-+ and D+K-++ • e+e-J/D(*)D(*)+nothing clearly seen • Look at Mrecoil (J/) when Mrecoil (J/ D) ~ M(D*) N=9.93.3 (4.5) Mrecoil (J/ D) ~ M(D) N=4.12.2 (2.1) P.Pakhlov (ITEP, Moscow)

  13. Summary • e+e- J/ (cc)res is studied in details: • (cc)res = c, c0, c’ are confirmed; angular analysis is done • (cc)res = J/, c1, c2, (2S) not seen • e+e- (2S) (cc)res is observed for the first time • Strong evidence for a new charmonium state at M~3.94 GeV: • produced in the process e+e- J/ X(3940) • small width • hint on the decay X(3940) into DD* P.Pakhlov (ITEP, Moscow)

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