Stephen Olsen U. of Hawai’i & 高能所 北京 YZ e otic X Mesons Sookyung Choi Scientist of the month Aug 2004, Korea

Constituent Quark Model (CQM) (& 6 antiquarks) Mesons: qq c:c: c +2/3 c:c: C -2/3  + : s -1/3 s +1/3 c -2/3 u -2/3 b +1//3 u +2/3  - : b -1/3 S =1/3 b +1/3 t -2/3 c +2/3 b -1/3 t +2/3 6 quarks Baryons: qqq u -2/3 d +1/3 s +1/3 u +2/3 d -1/3 s -1/3 Gell-Mann Zweig

Fabulously successful mesons q q

Are there other color-singlet arrangements? Pentaquarks: e.g. an S=+1 baryon (only anti-s quark has S=+1) Glueballs: gluon-gluon color singlet states Multi-quark mesons: qq-gluon hybrid mesons uc u c cc u d u s d Non-quark model states expected in QCD

Our approach:look for non-qq mesons cc uc u c 4 (& 6) quark states “hybrid” qq-gluon states u u u u d d

Beijing Spectrometer (BES)

J/    pp C -2//3 c +2/3 u +2/3 u -2/3 d -1/3 u +2/3 d +1/3 u -2/3 p p 

J/    pp This is the  c  pp What is this??? M(pp) GeV J.Z. Bai et. al (BES). PRL 91, (2003)

Fit the M(pp) distribution Best fit to this peak is a resonance with peak mass below the pp mass threshold M=1835 MeV no know  100MeV resonance

A pp bound state (baryonium)? p npp deuteron: loosely bound 3-q 3-q color singlets with M d = 2m p -  baryonium: loosely bound 3-q 3-q color singlets with M b = 2m p -  ? attractive nuclear force attractive force? There is lots & lots of literature about this possibility

Expectation for pp bound state meson m p +m p Above threshold X  pp ~100% below-threshold p and p annihilate to mesons I=0, J PC =0 -+ init. state: pp       ’ is common

Look in J/        ’ M(      ’) M=1833 MeV  70MeV m p +m p 

X(1835): “6-quark” meson? 3 quarks + 3 antiquarks Need to confirm J PC of the      ’ peak is 0 -+ Need to find it in other common 0 -+ pp annihilation channels jobs for BESIII u u u u d d

Charmonium is of particular interest because it is an especially good system to use to search for non-qq mesons

a cc meson has to fit into one of these slots: If it doesn’t, it is a good candidate for a non qq meson

B-factories produce lots of cc pairs 0 -+, or , 0 ++, 2 ++ C =+ states only

Lots new on the “XYZ” particles X(3872) –     J/  in B  K     J/  Z(3930) –DD in   DD Y(3940) –  J/  in B  K  J/  X(3940) – e + e -  J/  X & e + e -  J/  DD* Y(4260) –     J/  in e + e -      J/  Y(4325) –  +  -  ’ in e + e -   +  -  ’ Y(4008)? Y(4250) Y(4370) Y(4660) X(3880)  DD - e + e -  J/  DD X(4160)  D*D* - e + e -  J/  D*D* Z + (4430)   +  - B  K  +  ’ New Belle/BaBar results: (Summer 2007) Status spring 2007: confirmed by BaBar updated by Belle

I’ll concentrate on recent results.

X(3872) S-K Choi, SL Olsen et al,

X(3872) properties (PDG2007) M D0 + M D*0 = ± 0.4 MeV

M(  ) looks like     2 / dof = 43/39 (CL=28%) kinematic limit≈m  PRL CDF Belle Belle & CDF: J PC = 1 ++  most likely

What’s new with the X(3872)? BaBar confirms Belle’s DD  threshold enhancement Mass is 3.8 ± 1.2 MeV above WAvg X(3872)   J/  mass; (~3  is this significant? Both groups see a high mass value

Belle’s B  K S X & B  K ± X comparison  M = 0.22 ± 0.90 ± 0.27 MeV K S modeK ± mode “molecular” models predicted this to be <<1 (Braaten et al PRD ) “diquark-antidiquark” models predicted this to be 8±3 MeV (Maiani et al PRD ) Confirms an earlier BaBar result

Is there a cc slot for the X(3872)? 3872   r  J/  too small   r (  J/  ) too big 1 ++  (  c1 ’)   c    J/  ispin forbidden  D 0 D 0  thresh.suppressed  B  Kcc(J=2) suppressed 2 -+ (  c2 )

Y(3940) in B  K  J/  M≈3940 ± 11 MeV  ≈ 92 ± 24 MeV Belle PRL94, (2005) M(  J/  ) MeV M 2 (K  ) GeV 2 M 2 (  J  ) GeV 2 S-K Choi, SL Olsen et al,

Y(3940) properties Belle PRL94, (2005) M(  J/  ) MeV  (Y 3940   J/  > 7 MeV (an SU F (3) violating decay) ~ this is 10 3 x  (  ’   J/  (another SU F (3) violating decay) if the Z(3930) is the  c2 ’ the Y(3940) mass is too high for it to be the  c1 ’

Confirmed by BaBar this summer B ±  K ±  J/  B 0  K S  J/  M 2 (K  )  J  ) ratio Some discrepancy in M &  ; general features agree G.Cibinetto EPS-2007

Is there a cc slot for Y(3940) ? Can M(  c1 ’)>M(  c2 ’)?  c1 ’ Mass is low c”c” “ “  c0 ’ For any charmonium assignment,  [Y(3940)   J/  is too large.

The 1 -- states seen in ISR   ’)

e + e -   isr Y(4260) at BaBar 233 fb -1 Y(4260) BaBar PRL95, (2005) ~50pb M=4259  8 +2 MeV  = 88  MeV fitted values:

Not seen in e + e -  hadrons  (Y4260      J/  ) > 90% CL X.H. Mo et al, PL B640, 182 (2006) 4260 BES data ~3nb  peak  Y(4260)  +   J/  pb Huge by charmonium standards

“Y(4260)” at Belle (New) M=4247  MeV  = 108  19 ± 10 MeV -32 M=4008  MeV  = 226  44 ± 87 MeV -28 ??? C.Z Yuan et al (Belle) arXiv: To appear in PRL M=4259  8 +2 MeV  = 88  MeV BaBar values: Resonance? Thresh effect? …?

No 1 -- cc slot for the Y(4260) 4260 X.H. Mo et al, hep-ex/

Is the Y(4260) a cc-gluon hybrid? cc qq-gluon excitations predicted 30 yrs ago lowest 1 -- cc-gluon mass expected at ~4.3 GeV relevant open charm threshold is D**D (~4.28 GeV)  (  J/  ) larger than that for normal charmonium  (e + e - ) smaller than that for ordinary charmonium Horn & Mandula PRD 17, 898 (1977) Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, (2003) Isgur, Koloski & Paton PRL 54, 869 (1985) McNeile, Michael & Pennanen PRD 65, (2002) Close & Page NP B443, 233 (1995) Y(4260) seems to match all of these !!!

DD** thresholds in & “Y(4260)” 4.28-m D D** spectrum M(     J/  ) GeV No obvious distortions D1DD1D D2DD2D

BaBar’s      ’ peak at 4325MeV Nbkg = 3.1  1.0 Nevt = 68 (<5.7 GeV/c 2 )  2 -prob < 5.7 GeV/c 2 Y(4260) 6.5   (4415)1.2  Y(4320)29% e + e -   ISR      ’ M=4324  24 MeV  = 172  33 MeV above all D**D thresholds S.W.Ye QWG-2006 June 2006 Not Compatible with the Y(4260) D1DD1D D2DD2D 298 fb -1 (BaBar) hep-ex/ BaBar PRL (2007)

4325 MeV      ’ peak in Belle (new) M=4324  24 MeV  = 172  33 MeV 548 fb -1 X.L. Wang et al (Belle) arXiv: Two peaks! M=4664  11 ± 5 MeV  = 48  15 ± 3 MeV M=4361  9 ± 9 MeV  = 74  15 ± 10 MeV BaBar values (both relatively narrow) (& both above D**D thresh) (& neither consistent with 4260) 4260

Latest News electrically charged!! S-K Choi, SL Olsen et al, Belle, submitted to PRL

M(  ±  ’) from B  K  ±  ’ M 2 (K  ) GeV 2 M 2 (  ’ ) GeV 2 K. Abe et al (Belle) arXiv: K*  K  K 2 *  K  Veto M(  ’ ) GeV 6.5  M = 4433 ± 4 ±1 MeV  tot = MeV Nsig =124 ± 31evts

Comments on the Z + (4430) Not a reflection from the K  system ~ No significant signal in B  K  J/  It has non-zero charge  not cc or hybrid Mass, width & decay pattern similar to Y(4360) & Y(4660)

conclusions There seems to be a new hadron spectroscopy in the M=3.5~5 GeV region –Maybe more than one –Bodes well for BESIII, Super-B factories & PANDA Some states are narrow even though they are far above decay thresholds –e.g. Y(4660)   ’ & Z + (4430)     ’ have large Q but  ≈50 MeV characterized by large partial widths (Bfs) to hadrons+J/  (or  ’)  – Br(X(3872)   J/  ) > 4.3% (Isospin=1) –  (Y(3940)   J/  ) > 7 MeV (SU(3) octet) –  (Y(4260)      J/  ) > 1.6 MeV States that decay to  ’ not seen decaying to J/  (and vice-versa) –Bf(Y(4660)   ’) >> Bf(y(4660)   J/  )  same for Y(4360) & Z(4430   ’ –Y(4260) not seen in Y(4260)   ’ The new 1 -- states are not apparent in the e + e -  D ( * ) D ( * ) cross sections There is no evident transitions at the D**D mass threshold (mine)

New 1 -- states     J/      J/   ’ ’

some of the states are near thresholds, but this is not a universal feature D S D S thresholdsDD thresholds

D*D* DD* DD  tot Y(4660)Y(4360) Y(4260) Y(4008) None of the 1 -- peaks match structures in e + e -  hadrons Pakhlova (Belle) PRL 98, (2007)

Lots of pieces Y(4360) Y(4660) Y(4260) Y(4008) X(3872) X(3940) X(4160) Z(4430) Y(3940) Are they all from the same puzzle?

謝謝

Actual fit M= ± 6.7 MeV/c 2  < 153 MeV/c 2 (90% CL) J/    pp in the BES expt  2 /dof=56/56 fitted peak location