The XYZ mesons Stephen L Olsen University of

The XYZ mesons Stephen L. Olsen University of Hawaii PANIC-08 Nov 10 -14, 2008 Eilat

X(3872) X & Y mesons B K p+p-J/ Y(4260) Belle e+e- g. ISRp+p-J/ Y(3940) Belle Y(4008)? Ba. Bar M(p+p-J/ )-M(J/ ) Belle (Decay to final states with a cc pair & Sqi=0 ) M(p+p-J/ ) Ba. Bar B K w. J/ Y(4350) & Y(4460) Ba. Bar M(w. J/ ) e+e- g. ISRp+p- ’ Belle M(w. J/ ) X(3940) e+e- DD*J/ M(p+p- ’) X(4160) e+e- D*D*J/ Belle M(DD*) e+e- g. ISRLc. Lc M(D*D*) M(Lc. Lc)

Neutral cc X & Y mesons Name JPC G (Me. V) Decay modes Expts comment X(3872) 1++ <2. 3 pp. J/ ; g. J/ ; DD* Belle/CDF/D 0/Ba. Bar DD* molecule? X(3940) 0? + ~37 DD* (not DD, w. J/ ) Belle hc’’(? ) Y(3940) ? ? + ~30 (not DD*) Belle/Ba. Bar X(4160) 0? + ~140 (not DD, DD*) Belle Y(4008) 1 -- ~225 pp. J/ Belle Y(4260) 1 -- ~80 pp. J/ (not pp ’) Ba. Bar/CLEO/Belle Y(4350) 1 -- ~75 pp ’ Y(4660) 1 -- ~50 pp ’; Lc. Lc (? ) w. J/ D*D* (not pp. J/ ) hc’’(? ) ccg hybrid? Ba. Bar/Belle @Lc. Lc threshold

Are any of these standard cc charmonium? predicted measured

Is the 1++ X(3872) the cc 1’ (23 P 1) ? ? ? 3872 Me. V • Mass is too low • cc 1’ pp. J/ violates Ispin • Bf(X 3872 pp. J/ )>4% • G(g. J/ ) should be >>G(r. J/ ) • expt: G(g. J/ ) <<G(r. J/ )

Neutral cc X & Y mesons Name JPC G (Me. V) Decay modes Expts comment X(3872) 1++ <2. 3 pp. J/ ; g. J/ ; DD* Belle/CDF/D 0/Ba. Bar DD* molecule? X(3940) 0? + ~37 DD* (not DD, w. J/ ) Belle hc’’(? ) Y(3940) ? ? + ~30 (not DD*) Belle/Ba. Bar X(4160) 0? + ~140 (not DD) Belle Y(4008) 1 -- ~225 pp. J/ Belle Y(4260) 1 -- ~80 pp. J/ Ba. Bar/CLEO/Belle Y(4350) 1 -- ~75 pp ’ Ba. Bar/Belle Y(4660) 1 -- ~50 pp ’; Lc. Lc (? ) Belle w. J/ D*D* hc’’(? ) ccg hybrid? @Lc. Lc threshold It is pretty widely --but not universally-- accepted that the X(3872) is not a standard cc charmonium state. For a dissenting view, see C Meng & KT Chao PRD 75, 114002 (2007)

Could the Y(3940) be charmonium? Bf(B KY 3940)x. Bf(Y 3940 w. J/ ) G(Me. V) Belle (7. 1 ± 3. 1) x 10 -5 87± 34 Ba. Bar Avg (4. 9 ± 1. 1) x 10 -5 (5. 2 ± 1. 0) x 10 -5 33± 12 39± 11 er h t o r all sitions o f True cc) tran ( B K assuming Bf(B KY 3940)<Bf(B KJ/ ) = 1. 0 x 10 -3 G(Y 3940 w. J/ )>1 Me. V ny a n a th tion i r s e n h a hig c tr i x n 0 o 1 r > had c c d ure meas

Neutral cc X & Y mesons Name JPC G (Me. V) Decay modes Expts comment X(3872) 1++ <2. 3 pp. J/ ; g. J/ ; DD* Belle/CDF/D 0/Ba. Bar DD* molecule? X(3940) 0? + ~37 DD* (not DD, w. J/ ) Belle hc’’(? ) Y(3940) ? ? + ~30 (not DD*) Belle/Ba. Bar X(4160) 0? + ~140 (not DD) Belle Y(4008) 1 -- ~225 pp. J/ Belle Y(4260) 1 -- ~80 pp. J/ Ba. Bar/CLEO/Belle Y(4350) 1 -- ~75 pp ’ Ba. Bar/Belle Y(4660) 1 -- ~50 pp ’; Lc. Lc (? ) Belle w. J/ D*D* hc’’(? ) ccg hybrid? @Lc. Lc threshold

X(3940) & X(4160) = hc” &/or hc’’’ ? hc’’’ 4160 Me. V 3940 Me. V hc ” One, or the other, could be the hc”, but it seems very unlikely that one is the hc” and the other is the hc’’’

Neutral cc X & Y mesons Name JPC G (Me. V) Decay modes Expts comment X(3872) 1++ <2. 3 pp. J/ ; g. J/ ; DD* Belle/CDF/D 0/Ba. Bar DD* molecule? ? ? ? X(3940) 0? + ~37 DD* (not DD, w. J/ ) Belle hc’’(? ) Y(3940) ? ? + ~30 (not DD*) Belle/Ba. Bar ? ? ? X(4160) 0? + ~140 (not DD) Belle Y(4008) 1 -- ~225 pp. J/ Belle Y(4260) 1 -- ~80 pp. J/ Ba. Bar/CLEO/Belle Y(4350) 1 -- ~75 pp ’ Ba. Bar/Belle Y(4660) 1 -- ~50 pp ’; Lc. Lc (? ) Belle w. J/ D*D* hc’’(? ) ccg hybrid? @Lc. Lc threshold

1 -- ISR Y states not seen in D(*) G. Pakhlova et al (Belle): σ(e+e–→open charm) Y(466 0) DDπ PRL 101, 172001 EW N (4415) Y(4350) (4160) Y(4260) Y(4660) D* D* (4040) PRL 98, 092001 PRL 100, 062001 Λc+Λc– Y(4008) D D* (4415) (4160) Y(4260) (4040) Y(4008) ? Y(4350) DD Belle: Sum of all measured exclusive contributions (3770) PRD 77, 01103 Durham Data Base if Ruds=2. 285± 0. 03 This means that the ISR Y states have G(pp. J/ ( ’)) > 1 Me. V m oniu m r a h c r e fo Too larg

only 1 unassigned 1 -- cc slot

Neutral cc X & Y mesons Name JPC G (Me. V) Decay modes Expts comment X(3872) 1++ <2. 3 pp. J/ ; g. J/ ; DD* Belle/CDF/D 0/Ba. Bar DD* molecule? ? ? ? X(3940) 0? + ~37 DD* (not DD, w. J/ ) Belle hc’’(? ) Y(3940) ? ? + ~30 (not DD*) Belle/Ba. Bar ? ? ? X(4160) 0? + ~140 (not DD) Belle Y(4008) 1 -- ~225 pp. J/ Belle Y(4260) 1 -- ~80 pp. J/ Ba. Bar/CLEO/Belle Y(4350) 1 -- ~75 pp ’ Ba. Bar/Belle Y(4660) ? ? ? 1 -- ~50 pp ’; Lc. Lc (? ) Belle w. J/ D*D* hc’’(? ) ccg hybrid? @Lc. Lc threshold At most 1 of the 1 -- Y states can be conventional cc charmonium

The Z mesons Electrically charged counterparts of the X & Y mesons

The Z meson candidates 6. 5 M(p± ’) Ge. V Z(4430) M 2(p± ’) Ge. V 2 B K p+ ’ S. -K. Choi et al (Belle) PRl 100, 142001 c 1) Z 1(4050) Ge. V 2 Z 2(4250) M 2(p±c’ >6 M(p±cc 1) Ge. V B K p+cc 1 M 2(Kp’) Ge. V 2 R. Mizuk, R. Chistov et al (Belle) PRD 78, 072004

Z meson properties Name Z(4430) Mass(Me. V) 4433± 5 Width(Me. V) 45+35 -18 Decay mode p+ ’ Z 1(4050) 4051+24 -43 82+51 -29 p+cc 1 Z 2(4250) 4248+185 -45 177+320 -72 p+cc 1 Can’t be cc charmonium minimal quark content: ccud d c c u

Still controversial Z(4430) not confirmed by Ba. Bar (but neither do they rule it out). ta a d + ’ a r a p Belle K g in N B in le l t e e B e m e h G t f W o Q s i s ’ s ly th a n n o a. Bar t m t o l x p e n itz d at l a D te l l r u o f ep A r e b l l wi Arafat Gabareen Mokhtar talk at ICHEP-2008 B. Aubert et al (Ba. Bar) ar. Xiv/0811. 0564

What could they XYZ states be?

suggested possibilities (some references in backup slides) D(*) molecules (real or virtual) masses should be near M(D(*))+M(D(*)) mass thresholds Favored model for X 3872 M(D 0)+M(D*0)=3871. 8± 0. 4 M(X 3872)=3871. 4± 0. 4 diquark-diantiquarks cc-gluon hybrids Expect SU(3) multiplets LQCD: M>~4. 3 Ge. V Open charm thresh =MD+MD** 4285 (above Y 4260 peak) Non-zero charges are not allowed

Thresholds D(*) ( ) D*SDS* ? ? No p exchng for DSDS some of the states are near thresholds, but this is not a universal feature

no evidence for multiplet partners diquark-diantiquark expectations: Xu(3872) u c c u B+ K-Xu X+(3872) Xd(3872) u c c d d c c d B 0 K 0 X d c c u Expect: d M(Xd)-M(Xu)= 2(md-mu)/cosq 8 ± 3 Me. V L Maiani et al PRD 71, 014028 (20050 X-(3872) Bf(B 0 K-X+)Bf(X+ p+p 0 J/ ) Bf(B- K-X 0)Bf(X+ p+p-J/ ) ≈2

no X±(3872) isospin partner is seen B 0 K± p∓ p 0 J/y ? Ba. Bar B∓ KS p∓ p 0 J/y ? Ba. Bar Bf(B 0 K-X+)Bf(X+ p+p 0 J/y) < 0. 4 0 + + Bf(B K X )Bf(X p p J/y) (expect 2) B. Aubert et al (Ba. Bar) PRD 71, 031501

B 0 KSXd & B K±Xu with Xu=Xd? Ba. Bar, ar. Xiv: 0803. 2838 Ba. Bar Belle K± mode Belle Ba. Bar K± mode KS mode DM = 0. 22 ± 0. 90 ± 0. 27 Me. V Compared to 8± 3 Me. V DM = 2. 7 ± 1. 6 ± 0. 4 Me. V (Maiani et al PRD 71 014028)

What about in the X 3872 DD* channel? PRL 97, 162002, 2006 PRD 77, 011102, 2008 NEW 6. 4σ 4. 9σ B+& B 0 D 0 D*0 K B K D 0 D 0 p 0 +0. 9 M=3875. 2± 0. 7 -1. 8 ~2 higher than M in pp. J/ mode 347 fb-1 M=3875. 1 Is this Maiani et al’s partner particle? +0. 7 ± 0. 5 -0. 5 ~4 higher than M in pp. J/ mode

New results on X 3872 DD* from Belle B K D 0 D*0 D*→D 0π0 D*→Dγ y r a in m li e r P More details in Tagir Aushev’s talk @ this meeting 605 fb-1 Flatte vs BW similar result: 8. 8σ M=3872. 6 +0. 5 ± 0. 4 Me. V -0. 4 N. Zwahlen, T. Aushev et al (Belle) ar. Xiv/0810. 0358 h. M e t i s w mod e e Agr pp. J/ m fro

! ! How about cc-gluon hybrids? ! e c c t s e h f o l • qq-gluon excitations predicted 30 yrs ago l a h c ~4. 3 Ge. V • LQCD: lowest 1 cc-gluon mass t a m - QCD sum rules get lower values ~3. 7 Ge. V o t s m • relevant open charm threshold is D**D (~4. 28 Ge. V) e e s )larger than that for normal charmonium • G(pp. J/ ) 0 6 2 4 ( e ) for 1 states less than ordinary charmonium • Y G(e Horn & Mandula PRD 17, 898 (1977) -- Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003) Kisslinger et al, ar. Xiv 0805. 1943 (2008) Isgur, Koloski & Paton PRL 54, 869 (1985) Mc. Neile, Michael & Pennanen PRD 65, 094505 (2002) + - -- Close & Page NP B 443, 233 (1995)

DD** thresholds and the Y(4260), Y(4360) & Y(4660) D 4. 364. 26 - D 4. 28 - 3. 883. 85 - D DD Y(4360) & Y(4660) well above all DD** thresholds D D 4285 4. 66 - Belle

Scoreboard candidate Molecule? cq cq cc-gluon X(3872) X(3940) ? ? Y(3940) ? ? X(4160) ? ? Y(4008) ? ? Y(4260) ? ? Y(4350) ? ? Y(4660) ? ? Z(4430) ? ? Z 1(4050) ? ? Z 2(4250) ? ?

No model can accommodate all

Are there XYZ counterparts in the b- and s-quark sectors?

Y(4260) equivalent with b-quarks? Belle (e+e- p+p- (n. S)) Peaks not consistent with known bb states G(pp (n. S) ~ 1000 x too large for bottomonium K. F. Chen et al (Belle) ar. Xiv: 0808. 2445

Y(4260) equivalent with s-quarks? e+e- g f 0(980)f (e+e- p+p- f(1020)) Y(2175) f 0(980)f Ba. Bar f 0(980) p+p- M(f 0(980)f)

Confirmed by BES & Belle confirmed by BESII in J/ h f f 0(980) BES (e+e- f 0(980)f(1020)) Belle M(f 0(980)f Ge. V X. L. Wang et al (Belle) ar. Xiv: 0808. 0006 M. Ablikim et al (BES) PRL 100, 102003 (2008)

Maybe the X(1835) is one too? J/ g. X(1835) | p+p-h’ X(1835) M. Ablikim et al (BESII), Phys. Rev. Lett. 95: 262001, 2005 BES s s tly s mo

Concluding remarks • A number of “mysterious” mesons have been observed • They have large hadron-charmonium partial widths – Much larger than those seen in the charmonium system • There is no strong variations above DD** thresholds – As expected for cc-gluon hybrids • Some are near thresholds but not all – As expected for molecules, threshold cusps, etc. • No Isospin or SU(3) multiplet partners yet seen – As expected for diquark-diantiquark models • Similar structures in b- & (maybe) s-quark sectors

However, none of the proposed models have produced a compelling match to the experimental observations

zz le ? Lots of pieces pu 0) 3 4 (4 e Z Y(3940) ) sa m 0 4 9 3 Ar e th Y(4360) ey Y(4260) ) 0 16 08) 4 ( X Y(40 al lf ro m Y(4660) th e X( X(3872)

Thank you

Backup Slides

Some recent reviews • Galina Pakhlova ar. Xix: 0810. 4114 – This includes 64 references – See slides from her plenary talk @ ICHEP 08 • S. -K. Choi ar. Xiv: 0810: 3546 – See slides from her parallel talk @ ICHEP 08 • E. Braaten ar. Xiv: 0808. 2948 – 48 references, mostly on molecular-like models • S. Godfrey & S. L. O. ar. Xix: 0801. 3867 – 128 references, but almost a year old

Some theory references • L Maiani et al PRD 71, 014028 (2005) c c cc 1’ charmonium? • T-W Chiu & TH Hsieh • C Meng & KT Chao PRD 75, 114002 (2007) PRD 73, 111503 (2006) • D Ebert et al PLB 634, 214 (2006) • H Lipkin & M Karliner PLB 638, 221 (2006) … • NA Tornqvist PLB 590, 209 (2004) • ES Swanson PLB 598, 197 (2004) • E Braaten & T Kusunoki PRD 69 074005 (2004) • CY Wong PRC 69, 055202 (2004) • MB Voloshin PLB 579, 316 (2004) • F Close & P Page … PLB 578, 119 (2004) too light? ? P Lacock et al (UKQCD) PLB 401, 308 (1997)

B-factories produce lots of cc pairs 0 -+, 1 - - or 1++ 0 -+, 0++, 2++ 1 - - only C =+ states