Heavy Quarkonium Spectroscopy Riccardo Faccini University “La Sapienza” and INFN Rome Lepton Photon August Daegu, Korea

Quarkonium for Pedestrians Quarkonium is a bound state of a quark and an antiquark Quarkonium is a bound state of a quark and an antiquark Relevant quantum numbers: n,L,S,J Relevant quantum numbers: n,L,S,J Relationship with Parity and Charge Conj: Relationship with Parity and Charge Conj: P=(-1) L+1, C=(-1) L+S P=(-1) L+1, C=(-1) L+S Not all J PC allowed (e.g. 0 +-,0 --,1 -+,2 +- forbidden) Not all J PC allowed (e.g. 0 +-,0 --,1 -+,2 +- forbidden) : Decay Properties: Below open quark threshold (e.g. (cc)  DD) only electromagnetic or  s suppressed decays allowed  mostly narrow states Below open quark threshold (e.g. (cc)  DD) only electromagnetic or  s suppressed decays allowed  mostly narrow states Above open quark threshold (if DD decays allowed)  mostly broad states Above open quark threshold (if DD decays allowed)  mostly broad states What can we learn? What can we learn? Understanding of QCD: Understanding of QCD: ‘regular quarkonium’  tests of NRQCD, potential models, … ‘regular quarkonium’  tests of NRQCD, potential models, … ‘new states’  new forms of aggregations mediated by the strong interactions ‘new states’  new forms of aggregations mediated by the strong interactions Only charmonium and bottomonium considered here

Charmonium: state of the art M(MeV) J PC (2S+1) L J Increasing L  Increasing n  cc ’c’c J/  ’’  c2  c1  c0 hchc Open charm thr. Recent acquisitions Basically all states below the open charm threshold are observed and explained same J PC as J/  but mostly D wave !  (3770)  (4040)  (4160) (pot. Models) QWG: hep-ph/

Bottomonium: state of the art Open bottom thr.Increasing L  Increasing n  Y(1S) Y(2S) Y(3S)  P  b{2,1,0}  P  b{2,1,0}  b (x3) completelymissing 2 h b and 3 D wave states are narrow but not observed Y(1D) 8 narrow resonances still missing ! Unconfirmed J assignments of all the  b s (pot. Models) QWG: hep-ph/

Beyond the quarkonium Search for states with 2 quarks+”something else” Search for states with 2 quarks+”something else” New forms of aggregation New forms of aggregation Expected but never identified!!! Expected but never identified!!! Hybrids: qq+n gluons Hybrids: qq+n gluons Lowest state 1 -+ (forbidden for quarkonium) Lowest state 1 -+ (forbidden for quarkonium) Dominant decay H  DD** Dominant decay H  DD** Tetraquarks: [qq’][qq’] Tetraquarks: [qq’][qq’] Large amount of states Large amount of states small widths also above threshold small widths also above threshold Molecules: M[qq]M[q’q’] Molecules: M[qq]M[q’q’] Smaller number of states but still small widths also above threshold Smaller number of states but still small widths also above threshold Search for resonances: with non-quarkonium J PC unnaturally small widths not null charge: would be clear indication of something new going on

Measuring the quantum numbers Production: Production: ISR only produces with same quantum numbers as the photon (J PC =1 -- ) ISR only produces with same quantum numbers as the photon (J PC =1 -- )  only produces with C=+  only produces with C=+ Double charmonium production Double charmonium production e + e -   *  X cc 1 X cc 2 Possible only if quantum numbers of the two charmonia can be combined to give a Decay: Decay: Angular distributions of decay products depend on J P. Angular distributions of decay products depend on J P. Selection rules Selection rules Conservation of J Conservation of J Conservation of P,C in strong and e.m. decays Conservation of P,C in strong and e.m. decays  ISR e+e+ e-e- e-e- e+e+ X e-e- e+e+ X

Experiments e + e -  Charmonium (CLEO-c, BES-II) e + e -  Charmonium (CLEO-c, BES-II) L~10 33 /cm 2 /s L~10 33 /cm 2 /s E= GeV E= GeV e + e -  Y(4S): (BaBar, Belle, CLEO) e + e -  Y(4S): (BaBar, Belle, CLEO) L~10 34 /cm 2 /s L~10 34 /cm 2 /s Charmonium in B decays, ISR and  production Charmonium in B decays, ISR and  production Capability to measure J PC also in production Capability to measure J PC also in production pp colliders (CDF, D0) pp colliders (CDF, D0) High Xsection  copious production High Xsection  copious production Extremely high backgrounds Extremely high backgrounds 3M  (2S), 1.8 M  (3770) 58MJ/ , 14M  (2S) 383M Y(4S) 657M Y(4S) 1.5M Y(1S),1.9M Y(2S),1.7M Y(3S),9M Y(4S) Samples used in results 800pb fb -1 Disclamers: time is very short  could not cover everything theory statements are indicative

Quarkonium Spectroscopy

Updates on 1 -- charmonium states MeV  (3770)  (4040)  (4160)  (4415) M3771±24039±54192±64415±8 25±781±1473±1573±21 DD  not DD * 2 (2460) DD * 2 (2460) ~14σ improved measurements, including interference for the first time!!! First exclusive decay observed: DD * 2 (2460) [dominant]  3 D 1 candidate CLEO-c observes  (3770)   c0   Confirms 3 D assignment [ hep-ex/ ] arXiv: Belle-CONF-0771

Y(nS)  Y(mS) transitions The issue: Quarkonium transitions between 3 S 1 states described by the QCD Multipole Expansion Quarkonium transitions between 3 S 1 states described by the QCD Multipole Expansion Tests heavy quark and low energy hadronic systems Tests heavy quark and low energy hadronic systems BR(X(nS)  X(mS)  )/ BR(X(nS)  X(mS)  ) BR(X(nS)  X(mS)  )/ BR(X(nS)  X(mS)  )  invariant mass spectra  simplest PCAC matrix element expects enhancement at high masses  invariant mass spectra  simplest PCAC matrix element expects enhancement at high masses Data on Charmonium transitions well fitted by predictions Data on Charmonium transitions well fitted by predictions Bottomonium physics richer because of larger phase-space Bottomonium physics richer because of larger phase-space Y(2S) and Y(3S) transitions known for years Y(2S) and Y(3S) transitions known for years Y(4S) transitions (above open beauty threshold) much more difficult [high backgrounds]  only recent results Y(4S) transitions (above open beauty threshold) much more difficult [high backgrounds]  only recent results

Y(4S)  Y(nS)  As predicted by simplest PCAC matrix elements PRL 96,232001(2006) Phys.Rev.D75:071103,2007 Low mass structure to be understood!! Y(4S)  Y(1S)  Y(4S)  Y(2S) 

Y(3S)  Y(nS)  From CLEO’s Y(3S) [5x10 6 Y(3S)] From CLEO’s Y(3S) [5x10 6 Y(3S)] Fit to the Multipole Expansion parameters Fit to the Multipole Expansion parameters Results consistent with no ‘C’ term Results consistent with no ‘C’ term Breaking of the expansion The Multipole Expansion model fits the data (but not in its ‘naivest’ form) arXiv:

Y(2S)  Y(1S) ,  0 Rates predicted by QCD ME Rates predicted by QCD ME BF(Y(2S)   Y(1S))=(8.1±0.6)10 -4 [Kuang hep-ph/ ] Direct search from CLEO  5  evidence Direct search from CLEO  5  evidence BF(Y(2S)   Y(1S)) = (2.5±0.7±0.5)10 -4 BF(Y(2S)    Y(1S)) < E  -m  (MeV)

Quarkonium polarizations QCD predicts high p T S-wave quarkonium to be transversely polarized in pp collisions. Recent updates on J&  (2S) (CDF) and Y(nS) (D0): Recent updates on J&  (2S) (CDF) and Y(nS) (D0): Clear violation of NRQCD for J/ ,  (2S), Y(1S) [Y(2S) follows NRQCD] NRQCD CDF PRL88, (2002) arXiv: pb -1 J/  Y(1S)

B   c K*,h c K (*) Very little known about dynamics involving h c. Very little known about dynamics involving h c. NRQCD predicts Br(B   cJ K(*))~Br(B  h c K(*))~10 -4 NRQCD predicts Br(B   cJ K(*))~Br(B  h c K(*))~10 -4 recent measurements: recent measurements: Br(B 0   c K *0 )=(6.1±0.8±1.1)10 -4 Br(B +  h c K + )x Br(h c   c  ) < Br(B 0  h c K *0 ) x Br(h c   c  ) <  Suppression in h c production [or low Br(h c   c  )] arxiv:

The new zoology X(3872) X(3872) The 1-- family Y(4260) The 1-- family Y(4260) The 3940 family X(3940) The 3940 family X(3940) breaking news breaking news

X(3872): known facts Decays Decays X  J/  (original observation) X  J/  (original observation) Maybe J/  Maybe J/  BF(X  J/  BF(X  J/  BF(X  J/  BF(X  J/  X  J/  X  J/ Implications: C(X)=+1 C(X)=+1 C(  in J/  decay)=-1 C(  in J/  decay)=-1 I(  )=L(  )=1  consistent with J/  decay hyp. I(  )=L(  )=1  consistent with J/  decay hyp. Production Production only B decays so far only B decays so far No prompt e + e - production observed (BaBar No prompt e + e - production observed (BaBar arXiv: ) Belle+BaBar

Analysis of J PC of X(3872) Full angular analysis of X  J/  decays PRL 98: (2007) Only compatible options: J PC =1 ++ or 2 -+ (and with J(  )=1) Belle ( hep-ex/ ) disfavours P=-  J PC =1 ++

The X(3872) puzzle Open options DD* molecule DD* molecule Right above the threshold Right above the threshold favours DD* decay over J/  over J/  (as observed) favours DD* decay over J/  over J/  (as observed) Tetraquark Tetraquark Explains small width Explains small width Predicts a set of 4 states (2 charged and 2 neutral). Predicts a set of 4 states (2 charged and 2 neutral). Finding the charged state is critical Finding the charged state is critical M(MeV) J PC (2S+1) L J Increasing L  Increasing n  cc ’c’c J/  ’’  c2  c1  c0 hchc Open charm thr.  (3770)  (4040)  (4160) (pot. Models) X(3872)? Not matching any predicted state! Above DD threshold (allowed): should have large width but it is narrow Charmonium highly suppressed decay into J/  (isospin violation) More from theorists…

X(3872)  D 0 D *0 Belle [] observed X(3872)  D 0 D 0  0 Belle [ PRL 97, (2006) ] observed X(3872)  D 0 D 0  0 Confirmation and integration from BaBar in B  DD * K Confirmation and integration from BaBar in B  DD * K B + & B 0  D 0 D *0 K Mass and BR measurement Hints of X in neutral B decays Warning! very low significance BABAR-PUB-07/049 N.B.

X(3872):  and angular analysis First info on  1.3  ) cos(Helicity angle) J P = First angular analysis (still low stat) BABAR-PUB-07/049  2

X(3872): update on J/  Update mass and BF in B  XK, X  J/  B ±  XK ± B 0  XK S Consistent with: no mass difference no rate difference 6.5  (first obs.) Prior results: BaBar PRD73, (2006) Belle-CONF-0711

X(3872) mass Poor agreement among mass measurements: X  J/  and X  DD (*) differ by ~4  Neutral and charged B mesons in X  J/  by 1.5  TWO STATES? X(3872) & X(3876) ? Predicted by tetraquark model (but why so close to threshold?) J/  average DD average [my extrapolation]

The new zoology X(3872) X(3872) The 1-- family The 1-- family The 3940 family The 3940 family breaking news breaking news

The 1 -- family Several resonances observed in e + e -  Y  ISR (certainly J PC =1 -- ) Y(4260)  J/  A new state: Y(4260) PRL 95, (2005) Confirmation + J/  0  0 : CLEO PRD74, (2006) CLEO-c PRL 96, (2006) Yet another state Y(4350) PRL 98, (2007) Y(4350)   S 

The youngest of the 1 -- family NEW 5.8  Y   S  Y  J/  NEW Confirmation of BaBar Zoomed BaBar arXiv: arXiv:

Decay properties Y(4350) Y(4660) f 0 dominating? Threshold effects? Y(4008)Y(4260) High mass region DECAY PROPERTIES

D (*) D (*) in ISR Most of these 1-- states should preferentially decay into D(*)D(*) states. Can we see them? Most of these 1-- states should preferentially decay into D(*)D(*) states. Can we see them?  (3770),  (4040),  (4415) [regular charmonia] clearly visible, nothing else D*D*D*D* DD * DD DD π, not D(2010,2007)  Basically all R scan other than non-resonant continuum understood  [D (*) D (*) (  )] PRL 98, (2007) hep-ex/ arXiv: [Belle: arXiv: ] continuum Xsection (pb)

J/  KK in ISR Knowledge of the strangeness content of these resonances is critical to disentangle their nature Knowledge of the strangeness content of these resonances is critical to disentangle their nature CLEO-c already showed few e + e -  Y(4260)  J/  K + K - CLEO-c already showed few e + e -  Y(4260)  J/  K + K - Belle (ISR): first observation of e + e -  J/  K + K - and J/  K s K s Belle (ISR): first observation of e + e -  J/  K + K - and J/  K s K s e+e-  J/  K + K - e+e-  J/  K S K S  (e + e -  J/  K s K s )/  (e + e -  J/  K + K-)= Consistent with isospin (0.5) BELLE-CONF-0772

1 -- family: recap Not matching any potential model prediction Not matching any potential model prediction Too narrow Too narrow M(MeV) J PC (2S+1) L J J/  ’’ Open charm thr.  (3770)  (4040)  (4160) (pot. Models) Only seen in  (2S)  1 -- “new physics”? 4260 can be fit by a tetraquark model (decaying into J/  f 0 …) or a hybrid (with g   ) 4 Ys to place ! Why not the ordinary Y(4040)?

The new zoology X(3872) X(3872) The 1-- family The 1-- family The 3940 family The 3940 family breaking news breaking news

The 3940 family Observed in J PC (?) M (MeV)  (MeV) X e + e -  J/  X (X  DD * ) 0 -+, ±8<39 Y B  YK (Y  J/  1 ++,… 3943±1787±34 Z   Z (Z  DD) ±529±10 Z  DD Y  J/  X  DD* PRL 96, (2006) PRL 94, (2005) PRL 98, (2007)

Confirmation of Y(3940) (B  K  J/  +-0+-0 B   YK  B 0  YK S B0/BB0/B Isospin cons. New result, based on 350 fb -1 : Belle’s evidence for B  YK, Y  J/  confirmed  ~30MeV lower mass than Belle’s  Narrower width  Clear demonstration of decay into   Preliminary BF estimate similar to Belle’s (~10 -5 ) preliminary G. Cibinetto, talk at this conference M(J/  ) (GeV) Y(3940) closer to X(3940) Can they be the same state?

“Just” charmonium states? M(MeV) J PC (2S+1) L J Open charm thr.  (3770)  c1 (pot. Models)  c2  c0 ’c’c cc X Z X,Y Poor match with predictions Poor match with predictions Above threshold? Above threshold? If X≠Y, difficult to explain absence of Y  open charm If X≠Y, difficult to explain absence of Y  open charm Hybrid? Hybrid?

The new zoology X(3872) X(3872) The 1-- family The 1-- family The 3940 family The 3940 family breaking news!! breaking news!!

D D*D*D* D D* X(4160)  D * D * e + e -  J/  D (*) D (*) Obtain J/  D (*) D (*) samples through kinematic separation, look at m(D(*)D(*)) after background subtraction: M = 3942 ±6 MeV  tot =37 ±12 MeV N ev = 52 ±11 Inferred (Recoil mass) X(4160) claim: new state M = 4156 ±15MeV  tot = 37 ±21MeV N ev =  3.8  X(3940)Cross-check X(3940) is still there, 6.0  Something’s here, but it’s not X(3940) M(DD) M(D*D*) M(DD*) M(D * D) J/  D+ J/  D*+ Number of events One more particle to explain … J CP =0 -+ not excluded (  c (3S)) reconstructed BELLE-CONF-0705

The first charged state: Z(4430)! B ±  Z ± K s or B 0  Z  K ± Z ±   (2S)  ± Total significance: 7.3s M = (4433±4) MeV  = ( ) MeV BF(B  KZ)xBF(Z   (2S)  )=(4.1±1.0±1.3) Xcheck: separate in subsamples BF and mass consistent between B ± and B0 within large errors [in B ± decays M=(4430±9) MeV ; BF ± /BF 0 =1.0±0.4 ] Too narrow to be a reflection Prior search with no evidence: B  X + K with X+  J/  0 PRD 71, (2005) arXiv:

Summary M(MeV) J PC (2S+1) L J Open charm thr.  (3770)  (4040)  (4160) (pot. Models) cc ’c’c J/  ’’  c2  c1  c0 hchc X Z X,Y X(3872) the best tetraquark candidate Updated properties  (4415) The 1 -- family: Charmonia, tetraquarks, molecules, hybrids?!? News on the 3940 family + updates on Y(nS)  Y(mS) transitions Yet another particle: X(4160) [  c (3S)?] Z(4430): the first charged state

Summary M(MeV) J PC (2S+1) L J Open charm thr.  (3770)  (4040)  (4160) (pot. Models) cc ’c’c J/  ’’  c2  c1  c0 hchc X Z X,Y X(3872) the best tetraquark candidate (?) Updated properties  (4415) The 1 -- family: Charmonia, tetraquarks, molecules, hybrids?!? News on the 3940 family + updates on Y(nS)  Y(mS) transitions Yet another particle: X(4160) [  c (3S)?] Z(4430): the first charged state WHAT A MESS !!!! ( of data) The discovery and identification of a new spectroscopy seems close

Summary M(MeV) J PC (2S+1) L J Open charm thr.  (3770)  (4040)  (4160) (pot. Models) cc ’c’c J/  ’’  c2  c1  c0 hchc X Z X,Y X(3872) the best tetraquark candidate (?) Updated properties  (4415) The 1 -- family: Charmonia, tetraquarks, molecules, hybrids?!? News on the 3940 family + updates on Y(nS)  Y(mS) transitions Yet another particle: X(4160) [  c (3S)?] Z(4430): the first charged state WHAT A MESS !!!! ( of data) The discovery and identification of a new spectroscopy seems close

bakup

Fits to J/  KK invariant mass ‘Standard ‘ y(4415) + 1 BW: M = (4875±132) MeV  = (630±126) MeV single BW: M = (4430±38) MeV  = (254±49) MeV

Thresholds and new states X(3872) Y(4260) X(4160) XYZ(3940) Y(4350) Y(4660)

CLEO and Belle on 4260

Search for X(3872)  J/  in continuum X>2 ch  c production is consistent with the expected contributions from prompt  (2S) production feed-down to  c : no evidence of prompt  c1,2 No evidence of X(3872) production in e + e - annihilation.  c1,2 or X(3872)  c1  c2 X(3872) 386fb -1 J/  production observed in continuum while no evidence of  c states. arXiv:

Below open charm threshold