New Resonances at Belle Jolanta Brodzicka INP Kraków, for the Belle Collaboration ICFP 2005

1. New Resonances at Belle Jolanta Brodzicka INP Kraków, for the Belle Collaboration ICFP 2005 October 4th, 2005 Taiwan • Outline • X(3872) properties • Y(3940), a hybrid state? • X(3940), a new charmonium state? • Z(3930), an excited charmonium state? • Summary

2. 253fb-1 N=49.18.4 X+- J/ Intriguing X(3872) • X(3872)+- J/ discovered by Belle in 2003 in B+K++- J/ decay M= 3872.0 ± 0.6 ± 0.5 MeV <2.3 MeV @90% C.L. BF(BK X)BF( X+-J/)=1.31±0.24±0.13 10-5 • Confirmed by other experiments (BaBar, D0, CDF) and included in PDG2005 M(+-J/) • M and  do not fit well any potential model charmonium states • M(+-) peaks at kinematic limit ((770)-like) X(3872) 0J/ is isospin violating decay • MX ~ MD*0+ MD0  speculation that X might be a molecular D*0D0 bound state • JPC= 1++ favored by some models (Swanson, PLB 588, 189(2004)) • Expected admixture of (782)J/ and a small (770)J/ component in addition to D*0D0 Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

3. X(3872) region N=13.6±4.4 (4.0) BF(BK X)BF(XJ/)=1.8±0.6±0.110-6 M(J/) (XJ/)/(X+-J/) = 0.14±0.05 Evidence for X(3872) J/ • If X(3872)  J/  C=+1 for X(3872)  search for BK X(3872), X(3872) J/ decay • Mbc distributions in M(J/) bins  significant B signal only for M(J/)~MX(3872) • Fit Mbc in M(J/) bins  BK J/ signal yield versus M(J/)  CX(3872) =+1 established Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

4. Virtual (782)? N=12.4±4.1 (4.3) M(+-0 ) X(3872) J/ sub-threshold decay • Kinematical limit for X(3872) J/ is 7.5MeV below M  via virtual  • Search for BK X(3872), X(3872) J/, +-0 decay • BK +-0 J/candidates selected in E-Mbc signal region X(3872) +-0 J/ selected:|M(3J/) – 3872|<16.5 MeV • Mbcvs. E distributions fitted in bins of M(+-0 )  B signal yield versus M(+-0 ) • Significant B signal only for (782) region M(+-0 )>750 MeV • Background: 2.1±1.0 (from BK J/ and non-resonant BK +-0 J/) • Strong support for molecular D*0D0 interptetation • Further evidence of C=+1 for X(3872) BF(X +-0 J/)/BF( X +-J/) =1.0 ±0.4 ±0.3  large isospin violation! Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

5. S-wave 2/d.o.f=43/39 Favored by M(+-) P-wave 2/d.o.f=71/39 Disfavored N=12.5±3.9 (>5) Constraints on JPC of X(3872) I • Fit to M(+-) • For C=+1 states +- J/ final state is primarily J/, • J++ :  and J/ in a relative S/D-wave; J-+ :  and J/ in a P-wave • M(+-) at kinematical limit is suppressed by (p*J/)2L+1  shape of high-mass part of M(+-) provides some JPC information  PX(3872) =+1 is favored M(+-) Preliminary • X(3872) D0D00 observation • BKD0D00(KD0 D*0)candidates selected using E-Mbc • Enhancement in M(D0D00)MX observed • It is difficult to distinguish D0D00andD0 D*0 BF(BK X)BF(XDD)=1.6±0.4±0.310-4 • XDD makes J2 unlikely, for J=2 D-wave required, suppressed by (p*)5 Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

6. 2/d.o.f=18/9 MC expectations 2/d.o.f=34/9 |cos| |cos| Constraints on JPC of X(3872) II • Two-body decay BKX(3872)  constraints on X spin and K-X relative angular momentum • Full angular analysis limited by low statistic (NX50 events) • Rosner’s coordinate system:x-axis is negative of K direction in X rest frame, x-y plane defined by + and K, z-axis completes right handed system Rosner PRD 70, 094023 (2004) • Each JPC hypothesis is examined using most distinctive angular distribution • 0-+ hypothesis: and J/ in a P-wave • Predicted angular distribution: d2N/d(cos) d(cos)  sin2 sin2 (in the limit where X,  and J/ rest frames coincide) Poor fit to cos distribution  evidence against 0-+ Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

7. MC expectation 2/d.o.f=31/9 2/d.o.f=11/9 |cosl| |cosl| 2/d.o.f=5/9 |cos| Constraints on JPC of X(3872) III • 0++ hypothesis:  and J/ in relative S- or D-wave (D-wave disfavored by M(+-) and suppressed by phase space) • Predicted angular distribution: dN/d(cosl) sin2l • 1++ hypothesis:  and J/ in relative S-/D-wave • d2N/d(cosl) d(cos) sin2l sin2 Poor agreement  0++ ruled out Good agreement for both distr. 1++ favored Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

8. N=58±11 (8.1) M= 3943±11±13 MeV =87±22±26 MeV Observation of Y(3940)   J/ • Discovery of X(3872) encouraged further studies of h+J/ systems • BK  J/, +-0 candidates selected • B signal yield determine in M(J/) bins by performing fits to Mbc distributions • Strong near-threshold enhancement in M(J/) @ 3.94GeV BF(BK Y)BF(YJ/)=7.1 ±1.3 ±3.110-5 • Is Y(3940) threshold effect or new charmonium state? • Charmonium meson with this mass would dominantly decay to DD(*) • Y(3940) properties are similar to those predicted for some of the cc-gluon hybrid states Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

9. X(3940) ’c c c DD threshold Observation of X(3940) in e+e-J/ X annihilation • Double charmonium production in e+e- annihilation (J/ + c c ’c): large cross sections, difficult to understand within NRQCD  cc production in different processes not completely understood  theoretical interest renewed • Searching region extended above DD threshold with new data (350fb-1) • Spectrum of a J/ recoil mass studied • New peak observed in Mrecoil(J/) @ 3.94GeV=39±29MeV Fit result: BornBF( X(3940)>2 charged tracks ) =10.6±2.5±2.4 fb Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

10. ND*D=55±18 NDD=86±17 X(3940)DD N=0.2 +4.4 <8.1 –3.5 BF(X(3940)D*D) = 96 +45 ±22 % dominant decay mode -32 Search for X(3940) D(*)D • Full reconstruction of e+e-J/X, XD(*)D not practical • To increase efficiency only one D reconstructed • Spectrum of Mrecoil(J/D) is studied, other D(*) seen as peak in Mrecoil(J/D) (D* and D well separated) • Observed processes e+e-J/DD, J/DD* • Mrecoil(J/D) refited to MD or MD* to improve Mrecoil(J/) resolution • Search for XD(*)D in Mrecoil(J/) M(D(*)D) spectra X(3940)D*D N=24.5 ± 6.9 (5.0) M=3943 ± 6 MeV =15.4 ± 10 MeV BF(X(3940)DD) < 41% @90% C.L. Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

11. NJ/= 2.2 +4.5 –3.7 NX = 1.9 +3.2 < 7.4 @90% C.L. BF( X(3940)J/ ) < 26% @90% C.L. –2.4 Are X(3940) and Y(3940) the same particle? • search for X(3940)  J/  • J/  reconstructed from e+e-J/ J/  final state • M(J/ ) vs. Mrecoil(J/ ) studied to look for X(3940) for M(J/ ) – MX(3940) < 40 MeV Signal region for e+e-J/ X(3940), X(3940)  J/  for Mrecoil (J/ ) – MJ/<100 MeV Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

12. Observation of Z(3930) in   DD N=4111 (5.5) M=393142 MeV =2083 MeV MC expectation • Motivation: study  production of high mass cc states decaying into DD • Known radially excited 2S charmonium states ’ and ’c: M<MDD • 23PJ(’cJ) predicted to lie: 3.9-4.0 GeVand to decay mainly to DD • Search for cc statesproduced via   DD process by studying untagged mode e+e-e+e-DD • Pt(DD)<0.05GeV ine+e- cms  it restricts  virtualities and enhances exclusive   DD production • New peak observed in M(DD)@ 3.93 GeV • Pt(DD) distribution for Z(3930) region agrees with MC for exclusive two-photon DD production (2J+1) BF (ZDD) =1.13±0.30±0.18 keV Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

13. for 3.91< M(DD) <3.95 GeV/c2 Spin-2 dN/d(cos *)~sin4* 2/d.o.f=7/9 Spin-0 flat distr. 2/d.o.f=32/9 Z(3930) angular distribution • Study of the angle of D relative to the beam axis in the  cms frame • Events from the 3.93 GeVpeak tend to concentrate at small |cos * values Data prefer a J=2 assignment  Z(3930) is ’c2 the 23P2 charmonium state Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005

14. Summary Belle found: • More informations to explain X(3872) properties • X(3872) quantum numbers: JPC=1++ • New charmonium state X(3940) (c(3S)?) in double charmonium production • Z(3930) in  process, Z(3930) = ’c2 Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005