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New Resonances at Belle Jolanta Brodzicka INP Kraków, for the Belle Collaboration ICFP 2005 October 4 th, 2005 Taiwan Outline ‘ old’ X(3872) properties (in B K X) Y(3940) in B K J/ X(3940) in double charm production Z(3930) in γγ production Summary
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X(3872) + - J/ discovered by Belle in 2003 in B + K + + - J/ M= 3872.0 ± 0.6 ± 0.5 MeV ~ M D* 0 + M D 0 M= 3872.0 ± 0.6 ± 0.5 MeV ~ M D* 0 + M D 0 <2.3 MeV @90% C.L. narrow <2.3 MeV @90% C.L. narrow BF (B K X) BF (X + - J/ )=1.31±0.24±0.13 10 -5 BF (B K X) BF (X + - J/ )=1.31±0.24±0.13 10 -5 Confirmed by other exp. (D0, CDF, BaBar), included in PDG2005 Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Intriguing X(3872) 253fb -1 N=49.1 8.4 X + - J/ X + - J/ M( + - J/ ) M and do not fit well any potential model cc states Speculations: X is a D* 0 D 0 bound state (predicted by Tornqvist 1994) J PC = 1 ++ favored by some models (Swanson, PLB 588, 189(2004)) expected admixture of (782)J/ and (770)J/ components, expected admixture of (782)J/ and (770)J/ components, in addition to D* 0 D 0 (isospin viol. decays) in addition to D* 0 D 0 (isospin viol. decays) PRL 91, 262001
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Evidence for X(3872) J/ If X(3872) J/ C=+1 for X(3872) search for B KX, X J/ search for B KX, X J/ M bc distributions in M( J/ ) bins B K J/ signal seen only for B K J/ signal seen only for M( J/ )~M X(3872) M( J/ )~M X(3872) Fit M bc in M( J/ ) bins B K J/ signal yield vs M( J/ ) B K J/ signal yield vs M( J/ ) BF (B KX) BF (X J/ )=1.8±0.6±0.1 10 -6 C X(3872) =+1 established X(3872) region N=13.6±4.4 (4.0 ) M( J/ ) Theory expects: ~40 for Theory expects: ~40 for X(3872)= ’ c1 (2 3 P 1 ) hep-ex/0505037 (X J/ ) (X + - J/ ) = 0.14±0.05
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 X(3872) J/ sub-threshold decay Search for B K X(3872), X(3872) J/ , + - 0 X(3872) J/ , + - 0 M bc vs. E fitted in M( + - 0 ) bins B KX, X + - 0 J/ signal yield vs. M( + - 0 ) B KX, X + - 0 J/ signal yield vs. M( + - 0 ) Significant B signal only for M( + - 0 ) >750 MeV M( + - 0 ) >750 MeV Support for molecular D* 0 D 0 interpretation (Swanson) interpretation (Swanson) Further evidence of C=+1 for X(3872) for X(3872) BF (X + - 0 J/ ) BF ( X + - J/ ) =1.0 ±0.4 ±0.3 large isospin violation! Virtual (782)? N=12.4±4.1 (4.3 ) M( + - 0 ) Bkd=2.1±1.0 (782) Γ=8.4MeV hep-ex/0505037
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Constraints on J PC of X(3872) I Fit to M( + - ) if C=+1: + - J/ is primarily J/ J PC (X)= J ++ : and J/ in a S/D-wave J - + : and J/ in a P-wave M( + - ) at kinematical limit is suppressed by (p* J/ ) 2L+1 suppressed by (p* J/ ) 2L+1 shape of high-mass part of M( + - ) shape of high-mass part of M( + - ) provides some J PC information provides some J PC information Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 J ++ is favored X(3872) D 0 D 0 0 observation B K D 0 D 0 0 /K D 0 D* 0 candidates selected using E-M bc selected using E-M bc Enhancement in M(D 0 D 0 0 ) M X observed Difficult to distinguish D 0 D 0 0 / D 0 D* 0 BF (B K X) BF (X DD )=1.6±0.4±0.3 10 -4 S-wave 2/d.o.f=43/39 favored P-wave 2/d.o.f=71/39 disfavored M( + - ) N=12.5±3.9 (>5 ) X DD suggests that J 2 is unlikely, (at least 1 pair in D-wave, (at least 1 pair in D-wave, suppressed by p* 5 ) suppressed by p* 5 ) Preliminary hep-ex/0505038
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Constraining J PC [X(3872)] from angular distr. Full angular analysis limited by low statistics Approximation for B K X, X J/ , + -, J/ l + l - : X, and J/ rest frames coincide, X, and J/ rest frames coincide, angular distr. are predicted in the angular distr. are predicted in the joint ref. frame ( Rosner PRD 70, 094023 (2004)) joint ref. frame ( Rosner PRD 70, 094023 (2004)) Rosner’s coordinate system: x-axis is negative of K direction in X rest frame, x-axis is negative of K direction in X rest frame, x-y plane defined by + and K, z-axis completes x-y plane defined by + and K, z-axis completes right handed system right handed system Each J PC hypothesis examined using the most distinctive angular distr. the most distinctive angular distr. 0 - + hypothesis and J/ in a P-wave : and J/ in a P-wave : d 2 N/d(cos ) d(cos ) sin 2 sin 2 d 2 N/d(cos ) d(cos ) sin 2 sin 2 Poor fit to cos distribution evidence against 0 - + 2/d.o.f=18/9 2/d.o.f=34/9 MCexpectations |cos | |cos | hep-ex/0505038
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Constraints on J PC of X(3872) Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 0 ++ hypothesis: ( and J/ in S/D-wave) 2/d.o.f=31/9 MCexpectation |cos l | Poor agreement 0 ++ ruled out Predicted: dN/d(cos l ) sin 2 l 1 ++ hypothesis: ( and J/ in S/D-wave) Predicted: d 2 N/d(cos l ) d(cos ) sin 2 l sin 2 sin 2 l sin 2 2/d.o.f=11/9 2/d.o.f=5/9 |cos l | |cos | Good agreement 1 ++ favored
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Observation of Y(3940) J/ N=58±11 (8.1 ) M= 3943±11±13 MeV =87±22±26 MeV BF (B KY) BF (Y J/ ) =7.1 ±1.3 ±3.1 10 -5 Strong near-threshold enhancement in M( J/ ) @ 3.94GeV X(3872) + - J/ encouraged further studies of h +J/ systems: studies of h +J/ systems: J/ system in B K J/ , + - 0 J/ system in B K J/ , + - 0 B K J/ signal yield determined in M( J/ ) bins by fits to M bc distr. threshold effect? new charmonium state? cc at this mass dominantly DD ( * ) cc-g hybrid? (predicted states with properies similar to Y(3940), but M>4GeV) properies similar to Y(3940), but M>4GeV) PRL 94, 182002
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Observation of X(3940) in e + e - J/ X Fit result: X(3940 ) cccc cccc ’c’c’c’c DD threshold Born BF ( X(3940) >2 charged tracks ) =10.6±2.5±2.4 fb =10.6±2.5±2.4 fb (>4 ch.tracks required in analysis and J/ ll ) Recoil mass against J/ studied: New peak observed in M recoil (J/ ) @ 3.94GeV hep-ex/0507019 PRL 89, 142001 Double cc production in e+e - annihilation (J/ + c c ’ c ): large cross sections, difficult to understand by theory large cross sections, difficult to understand by theory Searching region extended above DD thr. with new data (350fb -1 ) X < 52MeV @ 90%C.L
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Search for X(3940) D ( * ) D BF >2 (X(3940) DD) 2 (X(3940) DD) < 41% @90% C.L. (conservative) (conservative) N DD = 86±17 N D*D = 55±18 BF >2 (X(3940) D*D) = 96 +45 ±22 % seems to be dominant decay mode -32 M recoil (J/ D) is studied: the other D ( * ) seen as peak in M recoil (J/ D) (D* and D signals well separated) (D* and D signals well separated) M recoil (J/ D) refited to M D or M D* to improve M recoil (J/ ) resolution to improve M recoil (J/ ) resolution e + e - J/ DD, J/ DD* observed Full reconstruction of e + e - J/ X, X D ( * ) D not practical (low eff.) one D reconstructed one D reconstructed M recoil (J/ ) M(D*D), M(DD) spectra X(3940) DD N=0.2 +4.4 <8.1 –3.5 X(3940) D*D N=24.5 ± 6.9 (5.0 ) M=3943 ± 6 MeV =15.4 ± 10MeV
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N J/ = 2.2 +4.5 –3.7 Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Are X(3940) and Y(3940) the same particle? Search for X(3940) J/ J/ reconstructed in e + e - J/ J/ M( J/ ) vs. M recoil ( J/ ) studied to look for X(3940) for M( J/ ) – M X < 40 MeV for M recoil ( J/ ) – M J/ <100 MeV Signal region for e + e - J/ X, X J/ X J/ N X = 1.9 +3.2 < 7.4 @90% C.L. BF ( X(3940) J/ ) < 26% @90% C.L. –2.4 X(3940) does not decay into J/ into J/
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 N=41 11 (5.5 ) M=3931 4 2 MeV =20 8 3 MeV MCexpectation (2J+1) BF (Z DD) =1.13±0.30±0.18 keV Observation of Z(3930) in DD hep-ex/0507033 Motivation: study production of high mass cc states decaying into DD cc states decaying into DD Known 2S charmonia ’ and ’ c : M<M DD 2 3 P J ( ’ c J ) predicted at ~3.9-4.0 GeV and to decay mainly to DD and to decay mainly to DD untagged in e + e - e + e - DD P t (DD)<0.05GeV in e + e - cms enhances exclusive DD production enhances exclusive DD production New peak in M(DD)@3.93 GeV P t (DD) distr. for Z(3930) peak agrees with MC for DD
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Study of the D angle relative to the beam axis in cms Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Z(3930) angular distribution for 3.91< M(DD) <3.95 GeV Spin-2 dN/d(cos *)~sin 4 * 2/d.o.f=7/9 Spin-0 flat distr. 2/d.o.f=32/9 Data prefer J=2 assignment Z(3930) is ’ c 2 2 3 P 2 charmonium state 2 3 P 2 charmonium state Events from the 3.93 GeV peak tend to concentrate at small |cos * values
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Jolanta Brodzicka, INP Kraków New Resonances ICFP 2005 Summary Belle at KEK-B: the goldmine for spectroscopy This year: new decay modes of X(3872), J PC =1 ++ established ( ’ c1 unlikely) new X(3940) in double charm production ( c (3S)?) Z(3930) in process ( ’ c2 likely) Earlier observations: ’ c (2S) D** (+D sJ ) c (2800) isotriplet Y(3940) (cc g hybrid?)
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