New States Associated with Charmonium from B A B AR and B ELLE Shuwei YE University of Texas at Dallas CLEO Seminar October 12, 2005

CLEO Seminar October 12, 2005Shuwei YE 2  Introduction: Charmonium Spectroscopy  The Experiments: B A B AR and BELLE  The Initial Surprise: X(3872)  New Heavy States: X(3940), Y(3940), Z(3930), Y(4260)  Properties of the X, Y and Z States  Interpretations and Theoretical Guidance  Summary Outline

CLEO Seminar October 12, 2005Shuwei YE 3 Mesons : Charmoniun States  c (2S), h c recently added by e + e  experiments (CLEO-c, BELLE, BaBar) ?

CLEO Seminar October 12, 2005Shuwei YE 4 Vector Charmonia Vector charmonia:  (4040),  (4160) and  (4415) inferred from  (e + e   hadrons)/  (e + e      ) (inclusively) R

CLEO Seminar October 12, 2005Shuwei YE 5 The B A B AR Experiment at SLAC ~600 physicists from 80 institutes in 11 countries  =0.56,  c  ~250  m

CLEO Seminar October 12, 2005Shuwei YE 6 B A B AR Detector The BABAR Experiment at PEP-II

CLEO Seminar October 12, 2005Shuwei YE 7 B A B AR Data (as of October 4, 2005) Integrated Luminosity  Runs 1-3: L = 123 fb -1  Run 4: L = 109 fb -1 L = 232 fb -1 analysed  Run 5: L > 60 fb -1

CLEO Seminar October 12, 2005Shuwei YE 8 The BELLE Experiment at KEK

CLEO Seminar October 12, 2005Shuwei YE 9 The BELLE Experiment at KEK ~1 km in diameter Mt. Tsukuba KEKB Belle 8 GeV (e - ) on 3.5 GeV (e + ) L =469 fb -1 collected upto 350 fb -1 analysed

CLEO Seminar October 12, 2005Shuwei YE 10 Belle Detector

CLEO Seminar October 12, 2005Shuwei YE 11 Sources of New Mesons/States Associated with Charmonium Many productions are accessible at B-factories:  B decays  Continuum production  Two photon interactions (C=+1)  Double CC interactions in e + e - annihilations  Initial state radiation (ISR) ( J PC =1 -- )

CLEO Seminar October 12, 2005Shuwei YE  significance Discovery of the X(3872)  (2S) Events/10 MeV/c 2 Belle 157M BBbar B ±  K ± X(J/     ) PRL 91, (2003) M(J/      ) - M(J/  ) (GeV/c 2 )

CLEO Seminar October 12, 2005Shuwei YE 13 Confirmation of the X(3872) X(3872) confirmed by CDF, D0 and B A B AR BaBar PRL 93, (2004) PRL 93, (2004) PRD 71, (2005) 220 pb pb -1 M(     J/  ) (GeV/c 2 ) Events / 5 MeV/c 2

CLEO Seminar October 12, 2005Shuwei YE 14 Evidence: X(3872)   J/ ,       J/  13.6 ± 4.4 X(3872)   J/  evts (>4  significance) M(  J/  ) X(3872)   J/  Br(X   J/  ) Br(X   J/  ) =0.14 ± 0.05 A virtual  (782)? X(3872)        J/  M(      0 ) Br(X  3  J/  ) Br(X  2  J/  ) = 1.0 ± 0.5 Isospin Violation!

CLEO Seminar October 12, 2005Shuwei YE 15 C=+1 is established X   J/  only allowed for C=+1 same for X  “  ” J/  (reported earlier) M(  ) for X      J/  looks like a 

CLEO Seminar October 12, 2005Shuwei YE 16 Observation: X(3872)  D 0 D 0  ±3.6 sig.evts (5.6  ) Br(B  KX)Br(X  DD  )=2.2 ± 0.7 ± 0.4x10 -4 Preliminary Cannot distinguish D 0 D 0  0 and D 0 D* 0 M(D 0 D 0  0 )

CLEO Seminar October 12, 2005Shuwei YE 17 Properties of the X(3872) Mass =  0.6  0.5 MeV/c 2,  <2.3 MeV (90% C.L.) very close to m(D 0 ) + m(D *0 ) 0 -- exotic Violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed DD allowed (  (3S)) 1 -+ exotic DD allowed 1 ++ favored 1 +- (h c ’ ) (  2 ) (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 253 fb -1 data: Further angular analysis and the observation of X(3872)  D 0 D 0  0  1 ++

CLEO Seminar October 12, 2005Shuwei YE 18 PRL 89,  Belle found double charmonium final states: (J/ ,  (2S))(  c,  c ) with surprisingly large cross-sections  No signal of C = -1 states in the J/  recoil mass spectrum  Confirmation by BaBar: large contradiction to NRQCD PRD 72, e + e   J/  cc Cross-sections (fb)

CLEO Seminar October 12, 2005Shuwei YE 19 X(3940) in e + e   J/  cc at BELLE M = (3943  6  6) MeV/c 2  < 52 MeV (90% C. L.) Stat. significance 5.0  above DD and D*D thresholds a new charmonium state 350 fb -1  c (1S) c0c0  c (2S) X(3940) hep-ex/

CLEO Seminar October 12, 2005Shuwei YE 20 X(3940)  DD X(3940)  DD: (No) N = Br (X(3940)  DD) < 41% (90 C.L.) X (3940)  DD*: (YES) N=24.5  6.9 (5.0  )  =15.1  10.1 MeV M=3943  6 MeV/c 2 Br (X(3940)  DD*) = ( ±22)%

CLEO Seminar October 12, 2005Shuwei YE 21 Y(3940) : near  J/  threshold enhancement in B  K  J/  at BELLE 253 fb -1 If it is treated as a S-wave BW: M = 3943  11  13 MeV/c 2  = 87  22  26 MeV  2 /d.o.f. = 15.6/8 stat. sig. = 8.1  PRL 94 (2005)  above D*D threshold  not clear BRs to DD or D*D final states a ccg hybrid charmonium?

CLEO Seminar October 12, 2005Shuwei YE 22 Z(3930) from two-photon events at BELLE Look at DD mass distribution in  events (p t (DD)<50 MeV/c): N = 41  11 (5.5  )  = 20  8  3 MeV M = 3931  4  2 MeV/c 2 p t distribution is consistent with  events hep-ex/ fb -1 hep-ex/

CLEO Seminar October 12, 2005Shuwei YE 23 Z(3930) from two-photon events at Belle Study helicity angle distribution: clear tendency for small |cos  | Helicity distribution is consistent with J=2 (~sin 4  ); J=0 (flat) disfavored:  2 =32.2/9  Z=  c2 ‘ (2J+1)   x B (Z  DD)=(1.13  0.30)keV

CLEO Seminar October 12, 2005Shuwei YE 24 Y(4260) from ISR at B A B AR : Motivation  2S  (3770), X(3872)  +   J/  Are there other vector charmonia or heavy particles that decay to  +   J/  ? ISR process provides e + e  collisions with a spectrum of energies for e + e    ISR e + e    ISR Y, Y  +   J/  J PC = 1    J  (2S),  (3770), … X(3872)(?)

CLEO Seminar October 12, 2005Shuwei YE 25 Access e + e  Annihilations through ISR BABAR accessible through ISR method Probe physics with C.M. energies below 10 GeV using Initial State Radiation (ISR) (X.C. Lou et al., Nucl. Phys. A675, 253 (2000)) which was validated with first BABAR data ISR  (2S)     ( X.C. Lou, Int. J. Mod. Phys. A16S1B, 486 (2001 )) Search for new particles in e + e    ISR     interactions

CLEO Seminar October 12, 2005Shuwei YE 26 Features of ISR Events  A small recoil mass against the hadronic system  Low missing transverse momentum  Preferentially along the beam directions Selection criteria makes use of these ISR features

CLEO Seminar October 12, 2005Shuwei YE 27 First Indication in  ISR  +   J/  An enhancement around 4.3 GeV/c 2 J/  e + e  or     L = 123 fb -1 >5k  (2S): little bkg No evidence for X(3872), but … ISR  (2S) X(3872)

CLEO Seminar October 12, 2005Shuwei YE 28 Selection Optimization of 232 fb -1 Data Optimize the selection by the quantity S / (3/2+  B ) where 3/2 corresponds to the search for a 3  -signal (G. Punzi physics/ )  S = N(  (2S)): clean  ISR  (2S) as signal calibration  B = N(bkg) in [3.8,4.2] and [4.4,4.8] GeV/c 2 from the data, scaled to the signal width Blind region [4.2,4.4] GeV/c 2 during optimization There is no reliable MC for continuum     J/  combinatorial background Data-driven optimization

CLEO Seminar October 12, 2005Shuwei YE 29 Control Sample:  ISR  (2S)   +   J/  Mass calibration and resolution Cauchy resolution function ( Breit-Wigner shape ) N(obs.) =  110 N(expect.) =  809 M(  (2S)) – M(PDG04) =  0.04 MeV/c 2 (correction applied to data) FWHM of Resolution Shape = 4.2 MeV/c 2 Data

CLEO Seminar October 12, 2005Shuwei YE 30 Results for L = 232 fb -1 data Unbinned likelihood fit with Rel-BW  PhaseSpace  Reso + 2 nd polynomial (BKG)  (2S) N = 125  23 Mass = 4258  8 MeV/c 2  = 88  23 MeV PRL 95, (2005) Y(4260)

CLEO Seminar October 12, 2005Shuwei YE 31 Significance of the Y(4260) Signal Method-1: Fit with null signal hypothesis We try 1 st, 2 nd, and 3 rd order polynomial different bin sizes: 5, 10, 20, 40, 50 MeV/c 2 Fit-Prob(  2, dof) = – for null signal Method-2: Try Run-4 data with the original selection criteria for Runs 1-3  Independent of the optimized criteria  Completely untainted(blind) to the Run-4 data Significance =  (  2 ) or  (-2ln( L 0 / L max )) 5 – 7  for the Run 4 sub-sample alone ( L = 109 fb -1 )  Significance > 8  for the full sample ( L = 232 fb -1 )

CLEO Seminar October 12, 2005Shuwei YE 32 Robustness and Optimization-Bias Checks Data subset  (2S) Fraction Y(4260) Fraction Full data (232 fb -1 )1.0 Run (123 fb -1 )  0.09 Run 4 (109 fb -1 )  0.09 J/  e + e  0.09 J/  +   0.10 With visible ISR   0.08 Good consistency between subsets for ISR  (2S) and ISR Y(  +  - J/  )  Reverse selection criterion one by one (individually)  Reverse selection criteria in pairs No evidence of significant bias in any reverse selection.

CLEO Seminar October 12, 2005Shuwei YE 33 Additional Checks  Are the selected J/  candidates real J/  ?  Are the selected ISR     J/  events genuine ISR events? Test by examining the kinematic distributions

CLEO Seminar October 12, 2005Shuwei YE 34 Real J/  Apply Y-sideband subtraction The Y signal region: [4.16,4.36] GeV/c 2 The Y sidebands: [3.86,4.06] + [4.46,4.66] GeV/c 2 +-+- e+e-e+e- Good agreement between Y Data and  (2S) data and Y Monte Carlo Events / 10 MeV/c 2

CLEO Seminar October 12, 2005Shuwei YE 35 ISR Events ? (1) Good agreement between Y Data and  (2S) data and Y Monte Carlo e+e-e+e- +-+- Events / 0.1 GeV/c

CLEO Seminar October 12, 2005Shuwei YE 36 ISR Events ? (2) Good agreement between Y Data and  (2S) data and Y Monte Carlo Cosine of polar angle of     J/  We do not tag the  ISR (only about 25% events with visible  ISR )

CLEO Seminar October 12, 2005Shuwei YE 37 Check for Reflections or Feeddowns No peak to reflect from  ISR K + K - J/  (particle mis-ID ) No peak to feed from  ISR       J/  (missing   )

CLEO Seminar October 12, 2005Shuwei YE 38 Other Backgrounds No structure  (2S) Feeddown of  (2S)  J/         Background from two-photon events is estimated by reversing the recoil mass criterion. A mix of two-  events + ISR events with additional neutral tracks

CLEO Seminar October 12, 2005Shuwei YE 39 One vs Two Resonances Hypothesis of two resonances Two-resonance fit yields: M 1 = 4251  6 MeV/c 2,  1 =58  18 MeV M 2 = 4334  1 MeV/c 2, consistent with the resolution Fit-prob(    is about 9.4% (not a significant improvement) The single-resonance fit-probability(    is about 2.6% We cannot exclude or establish a multi-resonance hypothesis No substantial improvement is obtained by including the  (4040),  (4160) and  (4415) in the fit

CLEO Seminar October 12, 2005Shuwei YE 40 m(     ) Distributions ISR  (2S): Good agreement between data and MC where  (2S)     J/   in MC is modeled by multi-pole model (PR D22, 1652 (1980)) ISR Y(4260): MC is phase space

CLEO Seminar October 12, 2005Shuwei YE 41 Single-Resonance Results For single-resonance hypothesis: Mass = 4259  MeV/c 2  = 88  MeV  Y  ee  B (Y  +  - J/  ) = Statistical significance > 8  J PC = 1 – – (inferred from ISR production)

CLEO Seminar October 12, 2005Shuwei YE 42 Comparison with R-Scan  R-scan plot (PDG04) shows a dip at 4.26 GeV  Peak cross section for  (e + e   Y)  B (Y  +   J/  ) is about 0.05nb  (e + e   hadron) =14.2  s=4.26GeV and R-scan accuracy of 0.56 nb Dip at 4.26GeV R sqrt(s) (GeV)

CLEO Seminar October 12, 2005Shuwei YE 43 Implication from  (Y     J/  )  Partial width of established charmonium states:  (2S)  (3770)  (  +   J/  ) 89 keV 45 keV (CLEO)  (e + e  ) 2.12 keV 0.26 keV  The Y width, a dip in R-Scan and  Y  ee  B (Y  +   J/  ) = 5.5 eV  Large  (Y  +  - J/  ) (>1 MeV),  (Y  e + e  ) < 0.35 keV (assuming  R<1/2 at 4.26 GeV in R-scan plot) Difficult to interpret as a conventional charmonium ?

CLEO Seminar October 12, 2005Shuwei YE 44 Theoretical Interpretations for Y(4260) Charmonium state ( ) ? Hybrid ( ) ? 4-quarks (bag, molecule, diquark-antiquark) ? From 1. S.L. Zhu, “The possible interpretations of Y(4260)”, PL B625, 212 (2005) 2. Felipe J. Llanes-Estrada “Y(4260) and possible charmonium assignment”, PRD 72, (2005) 3. L. Maiani, V. Riquer, F. Piccinini, A.D. Polosa “Four quark interpretation of Y(4260)”, PRD 72, (2005) 4. E. Kou, O. Pene, “ Suppressed decay into open charm for the Y (4260) being an hybrid ”, hep-ph/ Xiang Liu, Xiao-Qiang Zeng, Xue-Qian Li, “Possible molecule structure of the newly observed Y(4260)”, PRD 72, (2005) 6. Frank E. Close, Philip R. Page, “ Gluonic charmonium resonances at BaBar and Belle? ”, hep-ph/

CLEO Seminar October 12, 2005Shuwei YE 45 CLEO Can Help on Y(4260) CLEO can help resolve the Y(4260) structure (one/multi resonances?) and understand what it is. First-order cross-section at  s = 4.26 GeV   (e + e   Y(4260))  B (Y(4260)  +   J/  )  50 pb   (e + e    ISR  (2S))  B (  (2S)  +   J/  )  110 pb Advantages of running at  s = 4.26 GeV:  Larger acceptance (a factor of 5  6)  Much larger production cross-section (a factor of 1.6x10 3 )  Possible to tag  +    only, use recoil mass against  +  

CLEO Seminar October 12, 2005Shuwei YE 46 Properties of New Heavy States NameMass (MeV/c 2 ) Width (MeV) Production and decays What is it? X(3872)  0.6  0.5 <2.3 Produced in B-decays, X  J/ ,  J/ , D 0 D 0  , Molecule? X(3940) 3943  6 <52 Recoil J/ , Large B (  DD),  J/  not seen  c (3S)? Y(3940) 3943  11   22  26 Produced in B-decay, Y  J/  hybrid? Y(4260) 4259   J/     in ISR, D pair not seen, Dip in R-Scan 1 , hybrid? Z(3930) 3931  4  2 20  8  3 D pair in   ’ c2 ?

CLEO Seminar October 12, 2005Shuwei YE 47 Summary  Several new states/structure above  (3770) have been observed by B A B AR and BELLE   Current statistics is not sufficient to establish the Y(4260) structure as a single-resonance or multiple resonances. It seems incompatible with the charmonium spectroscopy due to large  (Y  +  - J/  ).  Some of these heavy states defy the expectation for conventional charmonia.

CLEO Seminar October 12, 2005Shuwei YE 48 Backup slides

CLEO Seminar October 12, 2005Shuwei YE 49 The PEP-II B-factory

CLEO Seminar October 12, 2005Shuwei YE 50 Optimized J/  Criteria Candidates: J/   l + l -  Well reconstructed tracks for both l   Require one e/  PID  J/  mass windows e + e - : [-95, +33] MeV/c 2 (with bremsstrahlung recovery)  +  - : [-40, +33] MeV/c 2  Cosine of lepton angle: |cos  l+ (J  )|<0.90 Apply J/  mass-constraint to l + l - Arbitrary Unit Events / 0.02

CLEO Seminar October 12, 2005Shuwei YE 51 Optimized     J/  Criteria We do not require the  ISR to be reconstructed (only about 25% events with visible  ISR ) Candidates:  +  - J/   Well reconstructed tracks for both    Require PID for both    No extra well-reconstructed track  p t *(Miss) < 2.5 GeV/c :  Including  ISR when detected : momentum balance   ISR along beam directions if missing   + helicity angle: cos   <0.9 for e + e - to remove soft beam-related e  bkg  Square of Recoil mass against  +  - J/  e + e - : [-1.06,+3.27] GeV 2 /c 4  +  - : [-1.06,+1.25] GeV 2 /c 4 Arbitrary Unit Events / 0.02 e+e-e+e-

CLEO Seminar October 12, 2005Shuwei YE 52 Control Sample:  ISR  (2S)   +  - J/  M(l + l - ): Good agreement between data and Monte Carlo e+e-e+e- +-+- Arbitrary Unit

CLEO Seminar October 12, 2005Shuwei YE 53 Control Sample:  ISR  (2S)   +  - J/  Minor difference due to no secondary  ISR in MC Arbitrary Unit +-+- e+e-e+e-

CLEO Seminar October 12, 2005Shuwei YE 54 Control Sample:  ISR  (2S)   +  - J/  Minor difference due to no secondary  ISR in MC Cosine of polar angle of     J/  in CM frame: preferentially along the beam directions Arbitrary Unit

CLEO Seminar October 12, 2005Shuwei YE 55 Original selection to Run-4 data Try the Run-4 data with the original Runs 1-3 selection criteria  Large fraction of signal-overlap  Statistical significance for this subset alone  (-2ln( L 0 / L max ))  7 