Near-threshold non-qq meson candidates Stephen Lars Olsen Seoul National University _ Heavy-Quark Hadrons at J-PARC Symposium at Tokyo Inst. Tech., June 22,2012

2 Constituent Quark Model 1964 The model was proposed independently by Gell-Mann and Zweig with three fundamental building blocks: 1960’s (p,n, )  1970’s (u,d,s mesons are bound states of a of quark and anti-quark: baryons are bound state of 3 quarks: Gell- Mann Zwieg

Google Search: quark: 41,000,000 results (0.13 seconds) Fabulously successful Quarks are probably the most well known particle physics quantity among the general public 鈴木 一朗 : 2,600,000 results (0.65 seconds)

Superseded by QCD in the 1970s: observed particles are color singlets 4 Λ = (uds) Mesons are color-anticolorpairs Baryons are red-blue-green triplets 3 primary colors  white color + complementary color  blue-yellow green-magenta red-cyan

QCD has other color-singlet combinations: Pentaquark:H-diBaryon Glueball Tetraquark mesons qq-gluon hybrid mesons u c u c cc u d u s d Other possible “white” combinations of quarks & gluons: _ _ _ _ u d u s d s _ _ u c u c _ _ _  D0D0 D* 0 _ S=+1 Baryon tightly bound 6-quark state Color-singlet multi- gluon bound state tightly bound diquark-diantiquark loosely bound meson-antimeson “molecule”

Where are they? u c u c cc u d u s d _ _ _ _ u d u s d s _ u c u c _ _ _  D0D0 D* 0 _

some history: low-mass scalar mesons The “light” scalar mesons J P = a0-a0- a0+a0+ ++ 00 a00a00  f0f -- 00 _ the “light” scalar-meson nonet More “light” scalar-mesons than quark model slots: , f 0 (980), f 0 (1370), f 0 (1500), f 0 (1710), f 0 (1790), …

light scalar nonet: masses are inverted  In qq meson nonets, the I=1 state (here the a 0 (980)) has no ss content.  No “light” J P =1 + and 2 ++ partner nonets in the same mass range. _ _ pseudoscalars scalars typical unique ss-quark content _

If not qq, then what? _ s q s _ _ q s q s _ _ _  K K _ tightly bound diquark-diantiquark loosely bound meson-antimeson “molecule” q Possibilities that have been suggested: J.D.Weinstein & N.Isgur PRD 27, 588 (1983) R.L.Jaffe PRD 15, 267 (1977) In color space: red+blue=magenta (antigreen) cyan+yellow=green (antimagenta) A colored diquark is like a antiquark A colored diantiquark is like a quark “nuclear” force

Institute of High Energy Physics -- Beijing -- To Tiananmen Square (~10 km) BESIII BEPC

11 BEPCII storage rings Beam energy: GeV Peak Luminosity: Design : 1×10 33 cm -2 s -1 Achieved : 0.65x10 33 cm -2 s -1 Beam energy measurement: Using Compton backscattering technique. Accuracy:  E beam /E beam ≈ 5  10 – 5   E beam ≈ 50 beam ≈ m 

BESIII Collaboration >300 physicists 49 institutions from 10 countries 11 Turkey: Turkish accelerator center Helmholtz Institute Mainz Johannes Gutenberg-University Mainz 29

The a 0 (980) & f 0 (980) straddle the KK threshold a 0 (980)  0 ) 2m K f 0 (980)     f 0 (980)     2m K _

a 0 (980) 0 f 0 (980) mixing isospin violation enhanced by K 0 – K + mass difference 2m K + = MeV2m K 0 = MeV 2m K + 2m K 0 expect a narrow line shape:  ≈2(m K 0 - m K + )=7.8 MeV PDG2010: M f 0 = 980 ± 10 MeV  f 0 = 40 ~ 100 MeV M a 0 = 980 ± 20 MeV  a 0 = 50 ~ 100 MeV N.N. Achasov, S.A. Devanin & G.N. Shestakov, Phys. Lett. B88, 367 (1979)

BES study of a 0 (980) 0 f 0 (980) mixing BESIII PRD 83, (2011)

a 0 (980) 0 f 0 (980) mixing results different models & parameterizations KK molecule model _ 90% CL upper limits Statistics limited, but BESIII already has lots more data.

J/  f 0 (980)  0,f 0 (980)  f 0 (980)   0  0 f 1 (1285) 3.7  f 1 (1285) 1.2  f 0 (980)   +  -  (1405) Large Isospin violations: from helicity analyses 1 st observations:  (1405)  f 0 (980)  0 & J/  f 0 (980)  0 BESIII PRL 108, (2012)

Anomalous f 0 (980) lineshape in  (1405)  f 0 (980)  0 Fitted mass: M ”f 0 ” = ± 0.4 MeV  ”f 0 ” = 9.5 ± 1.1 MeV The peak is midway between 2m K 0 & 2m K + & width ≈ 2(m K 0 - m K + ) PDG2010: M f 0 = 980 ± 10 MeV  f 0 =40 ~ 100 MeV BESIII PRL 108, (2012)

Effect of Triangle Singularity? J.J.Wu et al, PRL 108, (2012) Triangle Singularity (TS)a 0 —f 0 mixing K*K and KK are on shell enhancing TS contribution and isospin violation __ a 0 —f 0 mixing is too small to explain anomaly by itself f 0 (980) and  (1405) strongly influenced by the nearby KK & KK* thresholds. __  (1405)

Baryonium at the pp threshold? _

J/    This is the  c  pp the J/  ’s spin=0 partner What is this??? M(pp) GeV BESII PRL 91, (2003)

Fit the M(pp) distribution fit with a sub-threshold resonance _ M(pp) GeV M pp -2m p (GeV) BESII PRL 91, (2003) M=1859 MeV/c 2  < 30 MeV/c 2 (90% CL)  10  25 “cartoon” real fit

X(1835) has large BR to pp BESIII: our estimate from unpublished Crystal Ball data: implies a huge Br(X  pp): Since decays to pp are only possible from the tail of X(1835), such a BR indicates X(1835) has a huge coupling to pp ! J/    X Xtal Ball (unpublished) see L.Kopke, N.Wermes, Phys. Rep 174, 67 (1989)

X(3872) meson near the DD* threshold _

KEK Laboratory, Tsukuba Japan Fukushima Belle Detector e-e- e+e+ KEKB Mt Tsukuba

cc meson production in B decays d 1/3 b -1/3 C -2/3 C +2/3 d 1/3 S -1/3 W-W- K0K0 “Charmonium” “spectator” B0B0 _ _ _ Belle’s main purpose: Measure CP violations with B mesons that decay like this.  Nobel prize for Kobayashi &Maskawa in 2008

Charmonium (cc) meson spectrum _ All of the states below 2m D have been identified

The X(3872) in B  K     J/  discovered by Belle (140/fb) M(  J  ) – M(J/  )  ’      J/  X(3872)      J/  PRL 91, (2003)

X(3872)      J/  confirmed by many experiments ~6000 evts! M X = ± 0.16 ± 0.19 MeV M X = ± 0.27 ± 0.19 MeV M X = ± 0.46 ± 0.10 MeV CDF LHCb Belle: PRD CDF: PRL LHCb: arXiv: Belle

 +  - system in X(3872)   +  - J/  comes from    +  - X 3872   J/   CDF: PRL M(  +  - )    +  - lineshape Belle: PRD Problem: (cc)   J/  violates Isospin and should be strongly suppressed _

X(3872) not well matched to any unassigned cc level 3872 MeV _

X(3872) mass (in     J/  channel only) M X(3872) –(M D 0 + M D* 0 ) = ± 0.35 MeV _ M D 0 +M D* 0 = ± 0.30 MeV u c u c _ _ _  D0D0 D* 0 _ D 0 D* 0 molecule?? _ Isospin Violation in X(3872) decay: ≈on mass shell≈8 MeV off mass shell M X(3872) –(M D + + M D* - )= ± 0.35 MeV If so, the binding energy is very small

X (3872) -J/  relative sizes How can such a fragile object be produced in H.E. pp collisions?  heavy ion collisions?? Volume(J/  ) /Volume(X 3872 ) ≈ arXiv :  CDF ( meas )>3.1 ± 0.7nb vs  theory ( molecule )<0.11nb _ C. Bignamini et al, PRL 103, : d rms ( 208 Pb nucleus)≈5.5 fm Pb d rms (J/  ) ≈ 0.4 fm d rms (X 3872 ) ~ 8 fm J/  X(3872)

Venus (x3) Sun Very different objects!

Charged Z b1 (10,610) + and Z b2 (10,650) + in the b-quark sector

_  (4S)       (1S) ? ϒ (4S) “bottomonium” bb mesons 2M B = MeV

Belle:   (4S)   +  -  (1S) 2S 3S 4S  (4S)   (1S)  +   477 fb -1 52±10 evts N(  4S )N(  +  -  1S ) B (Y 4S   1S )  (Y 4S   1S )  theory 535x ± 109 ± 2 x ± 0.35 keV1.47 ± 0.03 keV Belle: PRD

2M B = MeV  (5S)       (1S) ? ϒ (4S) ϒ (5S)

Belle:   5S)     1S) 23.6 fb -1 vs 477 fb -1 ~1/20 th the data ~1/5 th the cross-section K.F. Chen et al (Belle) PRL 100, (2008) 325±20 evts!

“  (5S)” is very different from other  states Belle PRL100,112001(2008)  (MeV) X Anomalous production of  (nS)  +  - Recall Y(4260) with anomalous  (J/   +  - )  Is there a Y b equivalent close to  (5S)

“Y(5S)”   - Z b1,2 +   + ϒ (1,2,3S)  ϒ (3S)  ϒ (2S)  ϒ (1S) M( Υ (nS)π + ) max -- ++ ++ ++ Z b1 (10610) Z b2 (10660) 10,610 MeV 10,660 MeV

“Y(5S)”   - Z b1,2 +   + h b (1,2P)  h b (1P)  h b (2P) M(h b  + ) Z b1 (10610) Z b2 (10660) -- ++ ++ 10,610 MeV 10,660 MeV

Z b (10610) M=  2.0 MeV  =18.4  2.4 MeV Z b (10650) M=  1.5 MeV  =11.5  2.2 MeV Belle PRL 108, Summary of parameter measurements m B +m B* 2m B* March 2012

Z b1 & Z b2, “smoking guns” for multiquark mesons u b d b  decays to ϒ (nS) & h b (nP)  must contain bb pair  electrically charged  must contain ud pair _ _

B-B* & B*-B* molecules?? B B* b b _ B-B* “molecule” B* b b _ B*-B* “molecule” _ _ __ Z b (106010) ± Z b (106050) ± M Z b (106010) –(M B +M B* ) = ± 1.8 MeV M Z b (106010) –2M B* = ± 1.8 MeV Slightly unbound threshold resonances?? M=  1.7 MeV  =15.5  2.4 MeV M=  1.5 MeV  =14.0  2.8 MeV PDG: M B + M B* =  0.6 MeV M B* + M B* =  1.0 MeV Belle: _ _

Summary Lots of new particles & threshold effects found recently Lots of work for theorists to do… KK/KK* thresholds have large influences on f 0 /a 0 (980) &  (1405) X(1860) near NN threshold  pp bound state (baryonium)? X(3872) near DD* threshold  D 0 D* 0 bound state? Z b1 (10,610) * Z b2 (10660)  BB* & B*B* resonances? _ _ _ _ _ _ _ _

Thank you 감사합니다 ども ぅ ありがと ぅ

mesons come in nonets J P =0 - J P =1 - K* 0 K* + K* - K* 0 _ 00 -- ++   S-wave n r =0 S-wave n r =0 (  +,  0,  - )=lightest (  +,  0,  - )=lightest

49 baryons come in octets & decuplets M=????MeV M=1533 MeV M=1385 MeV M=1232 MeV J P =1/2 + J P =3/2 + all S-waves all n r =0 ?? M=1672 MeV --

 - not the 1 st Baryon correctly predicted pg MeV KN threshold 1959!! R. Dalitz S.F. Tuan

pg 698 m K +m N threshold  (1405) discovered in 1961 J P =1/2 -

Is the  (1405) a uds state? There are no octet partners with this  m (lowest ½ -   state =   (1535)  ) quark model fails for the 1 st baryon found above the S-wave octet & decuplet. Dalitz spent years trying to fit the  (1405) into the quark model, without success