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Some Topics in Hadron Spectroscopy: Funny Things that Happen at Thresholds

Some Topics in Hadron Spectroscopy: Funny Things that Happen at Thresholds. Stephen Lars Olsen Seoul National University. Constituent Quark Model. Gell-Mann. The model was proposed independently by Gell-Mann and Zweig in 1964 with three fundamental building blocks:

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Some Topics in Hadron Spectroscopy: Funny Things that Happen at Thresholds

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  1. Some Topics in Hadron Spectroscopy: Funny Things that Happen at Thresholds Stephen Lars Olsen Seoul National University

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

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 Superseded by QCD in the 1970s:observed particles are color singlets color + complementary color  white white 3 primary colors  blue-yellow green-magenta red-cyan Λ=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

  4. What about other color-singlet combinations? Pentaquark: H-diBaryon Glueball Tetraquark mesons qq-gluon hybrid mesons Other possible “white” combinations of quarks & gluons: u d u d s _ u tightly bound 6-quark state S=+1 Baryon d s u s d Color-singlet multi- gluon bound state D0 _ c _ u loosely bound meson-antimeson “molecule” c tightly bound diquark-diantiquark u _ p _ u c _ _ u _ D*0 c _ _ c c

  5. _ 1st evidence for non-qqmesons The “light” scalar-meson nonet?? JP=0+ 800 800 k+ k0 The “light” scalar mesons 980 980 a00 f0 a0- a0+ 980 s 600 _ k- k0 800 800

  6. light scalar nonet masses are inverted scalars pseudoscalars unique typical Also: • No “light” JP=1+ and 2+ partner nonets in the same mass range. • In qq meson nonets, the I=0 state (here the a0(980)) has no s-quarks. • m(f0(980))m(a0(980)) implies “ideal” mixing & small s-quark content in f0(980). _ _ strong couplings of the a0(980) & the f0(980) to KK indicate strong OZI-rule violations

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

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

  9. a0(980)0 f0(980) mixing N.N. Achasov, S.A. Devanin & G.N. Shestakov, Phys. Lett. B88, 367 (1979) isospin violation enhanced by K0 – K+ mass difference 2mK+= 987.4 MeV 2mK0= 995.2 MeV PDG2010: Mf0= 980 ± 10 MeV f0= 40 ~ 100 MeV Ma0= 980 ± 20 MeV a0= 50 ~ 100 MeV 2mK+ expect a narrow line shape: G≈2(mK0-mK+)=7.8 MeV 2mK0

  10. BES study of a0(980)0 f0(980) mixing BESIII PRD 83, 032003 (2011)

  11. a0(980)0 f0(980) mixing results _ KK molecule model 90% CL upper limits different models & parameterizations Statistics limited, but we should have lots more data soon

  12. J/f0(980)p0,f0(980)pp BESIII arXiv:1201:2737 (PRL)  last week! from helicity analyses h(1405) h(1405) f0(980)+- f0(980)00 f1(1285) 3.7s f1(1285) 1.2s 1st observations: (1405)f0(980)p0 & J/ygf0(980)p0 Large Isospin violation:

  13. Anomalous f0(980)lineshapein h(1405)f0(980)p0 BESIII arXiv:1201:2737 • Fitted mass: • M”f0”= 989.9 ± 0.4 MeV • ”f0”= 9.5± 1.1 MeV The peak is midway between 2mK0 & 2mK+ • & width ≈ 2(mK0 - mK+) PDG2010: Mf0= 980 ± 10 MeV • f0=40 ~ 100 MeV

  14. Effect of Triangle Singularity? J.J.Wu et al, arXiv:1108.3772 Triangle Singularity (TS) a0—f0 mixing 1405 1405 _ _ K*K and KK are on shell enhancing TS contribution and isospin violation a0—f0 mixing is too small to explain anomaly by itself

  15. The X(3872) & the DD*open charm threshold _

  16. KEK Laboratory, Tsukuba Japan JParc Belle Detector Mt Tsukuba e- e+ KEKB

  17. _ cc meson production in B decays C+2/3 “Charmonium” _ b-1/3 C-2/3 B0 W- d1/3 _ S-1/3 “spectator” K0 d1/3 Belle’s main purpose: Measure CP violations with B mesons that decay like this.  Nobel prize for Kobayashi &Maskawa in 2008

  18. The X(3872) in BK p+p-J/y discovered by Belle (140/fb) PRL 91, 262001 (2003) y’p+p-J/y X(3872)p+p-J/y M(ppJ/y) – M(J/y)

  19. X(3872)p+p-J/y recent results LHCb Belle CDF ~6000 evts! MX = 3871.61 ± 0.16 ± 0.19 MeV MX = 3871.96 ± 0.46 ± 0.10 MeV CDF: PRL 103 152001 MX = 3871.85 ± 0.27 ± 0.19 MeV LHCb: arXiv:1112.5310 Belle: PRD 84 052004

  20. What is known about the X(3872) 1) It has C=+1: X(3872)rJ/y and gJ/y are well established XgJ/y’ Xp+p-J/y rp+p- lineshape BaBar PRL 102,132001 CDF: PRL 96 102002 1++ 2- + 2) JPC = 1++ most likely 2-+ cannot be ruled out c2 =4.60 c2=0.56 Belle: PRD 84 052004 c2 =1.56 c2=5.24 2-+ has higher c2 and fewer dof than 1++

  21. What is known, continued Nevts =4.2±7.8 B0X+K- 3) Isospin = 0, probably… No (narrow) charged partners are seen; limits are well below Ispin=1 expections B+X+K0 no signal Belle: PRD 84 052004 4) Xp+p-J/y (discovery mode), violates I-spin

  22. _ 1++ cc assignment? cc1 ‘ pinned to: Mcc2=3930 MeV ‘ • Mass is too low? • 3872 vs 3905 MeV • nr=2 splitting> nr=1 • Scaling the Bf(p+p-J/y) • by cc theoretical value • for G(gJ/y) gives: • G(p+p-J/y)≈ 45 keV, • ~100x larger than other • cc Ispin violating widths. _ 3872 MeV _

  23. X(3872) mass(in p+p-J/ychannel only) D0D*0 molecule?? _ D0 _ c u _ p _ _ u D*0 c Isospin Violation in X(3872) decay: • MD0+MD*0=3871.79 ± 0.30 MeV MX(3872) –(MD0 + MD*0) = -0.12 ± 0.35 MeV _ ≈on mass shell ≈8MeVoff mass shell MX(3872) –(MD+ + MD*-)= -7.74 ± 0.35 MeV

  24. Consensus (?) X(3872) is some kind of a mixture of the cc1and a D0D*0 Molecule. ‘ _ D0D*0 molecule _ D0 _ c u c _ p c _ _ _ u D*0 c

  25. B(*)B* threshold states B*B* BB* BB

  26. ϒ(4&5S) “bottomonium” bb mesons _ ϒ(5S) ϒ(4S) 2MB = 10358.7 MeV

  27. “(5S)” is very different from other  states Anomalous production of (nS)+- Belle PRL100,112001(2008) (MeV) X10--2

  28. Belle: G(4,5S)p+p-(1S) (4S)  (1S) p+p- 2S 3S 4S (4S)  (1S) p+p- 325±20 evts! 477 fb-1 23.6 fb-1 Belle: PRL 100 112001 52±10 evts ~1/20th the data ~1/5ththe cross-section Belle: PRD 75 071103

  29. Look at p+p-recoil mass in (5S)+-+ X hb(1P) X=(1S) (2S) hb(2P) (3S) 121.4 fb-1 MM(+-) spectrum hb(1,2P)JPC=1+- 1st observations MM(+-) residuals Belle: PRL 108 032001

  30. MM(0) hb(1,2P) _ (bb) : S=0 L=1 JPC=1+- January Belle PRL 108, 122001 Expected mass  (Mb0 + 3 Mb1 + 5 Mb2) / 9 MHF test of hyperfine interaction Deviations from CoG of bJmasses hb(1P)(1.6  1.5) MeV/c2 hb(2P)(0.5 +1.6 ) MeV/c2 -1.2 Agrees with expectations Previous search BaBar 3.0 (3S) → 0 hb(1P) arXiv:1102.4565

  31. G[(5S) hb(nP) +- ] is large hb(2P)~85,000 evts hb(1P)~50,000 evts spin-flip for hb(1P) = for hb(2P) no spin-flip Process with spin-flip of heavy quark is not suppressed Mechanism of (5S) hb(nP) +- decay is exotic

  32. Resonant structure of “(5S)” hb(nP)+- MeV/c2 MeV _ M1 = MeV/c2 ~BB* threshold MeV/c2 MeV 1 = MeV _ _ ~B*B* threshold MeV/c2 M2 = 2 = MeV measure (5S)hb yield in bins of MM() PHSP PHSP X hc M(hb(2P)+) M(hb(1P)+) non-res.~0

  33. Look at “Υ(5S)”Υ(nS) p+p- Dalitz distributions for events in Y(nS) signal regions. 9.43 GeV <MM(π+π-) < 9.48 GeV 10.05 GeV <MM(π+π-) < 10.10 GeV 10.33 GeV <MM(π+π-) < 10.38 GeV Υ(1S)π+π- Υ(3S)π+π- Υ(2S)π+π- max M2(ϒπ±) M2(π+π-) M2(π+π-) M2(π+π-) To exclude contamination from gamma conversions we require: M2(π+π-) > 0.16 GeV2 M2(π+π-) > 0.20 GeV2 M2(π+π-) > 0.10 GeV2 Belle PRL 108, 122001

  34. Fit results: (5S) (3S)+- (5S) (2S)+- (5S) (1S)+- M(Υ(2S)π)max M(Υ(1S)π)max M(Υ(3S)π)max M=1061143 MeV M=1060923 MeV M=1060823 MeV Zb1 =22.37.74.0 MeV =24.23.13.0 MeV =17.63.03.0 MeV M=1065212 MeV M=1065763 MeV M=1065123 MeV Zb2 =8.42.02.0 MeV =16.39.86.0 MeV =13.33.34.0 MeV

  35. Summary of parameter measurements mB+mB* 2mB* Zb(10610) Zb(10650) M=10607.22.0 MeV M=10652.21.5 MeV =18.42.4 MeV =11.52.2 MeV last month Belle PRL 108, 122001

  36. _ _ B-B* & B*-B* molecules?? B Zb(106050)± Zb(106010)± B* b b b _ _ b _ _ B* B* _ _ B-B* “molecule” B*-B* “molecule” MZb(106010) –(MB+MB*) = + 3.6 ± 1.8 MeV MZb(106010) –2MB* = + 3.1 ± 1.8 MeV Slightly unbound threshold resonances?? M=10608.11.7 MeV M=10653.31.5 MeV Belle: =15.52.4 MeV =14.02.8 MeV MB* + MB* = 10650.2  1.0 MeV PDG: MB + MB* = 10604.50.6 MeV

  37. New result for IWHSS’12:1st observation of the hb(2S)

  38. 1st: hb(1S) signals from hb(nP) hb(1S) hb(1,2P)ghb(1S) are expected to be prominent (20%~50%) g Final state: p+p-gX hb hb X Bondar, Mizuk (Belle) ArXiv 1110.2251 hb(1P)ghb(1S) measure hb yields in bins of MM(p+p-g) (require 10.59<MM(p)<10.67 GeV, i.e. =MZb1,2) Belle -1.4 DMhfs(1S)=59.3±1.9+2.4 MeV M[hb(1S)]=9401.0±1.9+1.4 MeV G[hb(1S)]=12.4+5.5 +11.5MeV -2.4 “ϒ(5S)”p+p-U(2S) preliminary -4.6 -3.4 hb(2P)ghb(1S) Bf[hb(1P)ghb(1S)]=50+13 % -9 “ϒ(5S)”p+p-hb(1P) ϒ(2S) hb(1S) MM(p+p-g) MM(p+p-)

  39. Comparisons: hb(1S) results PRL 101, 182003 (2008) Bondar, Mizuk, et al (Belle)ArXiv 1110.2251 Belle BaBar hb(1P)ghb(1S) -4.8 -1.4 ϒ(3S)ghb(1S) PRD 81, 031104 (2010) hb(2P)ghb(1S) NRQCD LQCD CLEO ϒ(3S)ghb(1S) Reasonable agreement among experiments and with theory

  40. 1st observation of the hb(2S) hb(2P)ghb(2S) is expected to be the dominant decay mode (20%~50%) g Final state: p+p-gX hb hb X New!!! Belle hb(2P)ghb(2S) measure hb(2P) yields in bins of MM(p+p-g) (require 10.59<MM(p)<10,67 GeV, i.e. =MZb1,2) DMhfs(2S)=24.3±3.5+2.8 MeV -1.9 preliminary M[hb(2S)]=9999.0±3.5+2.8 MeV -1.9 Bf[hb(2P)ghb(2S)]=47.5±10.5+6.6 % -7.7 MM(p+p-g)

  41. Comparison: hb(2S) “signals” Belle: IWHSS’12 April, 2012 Seth: Trento April 2012 ϒ(2S)ghb(2S)? Belle: CLEO hb(2P)ghb(2S) Bf[hb(2P)ghb(2S)] about right   anomalously large production rate (~0.2✕cb1 rate) MM(p+p-g)  strong disagreement with theory  agrees with theory ≈5σ discrepancy

  42. LQCD predictions for DMhfs(1,2S) DMhfs(1S) DMhfs(2S) BaBar/CLEO DMhfs(1S) Belle CLEO Belle Meinel PRD82, 114502 (2010) DMhfs(2S) Belle cc Belle HP-QCD PRD85, 054509 (2012) m2 p

  43. BESIII c(2S)g (KsK+p-) 106M  BESIII preliminary y’ M1 E1 hc(2S) cc1 cc1 hc(2S) BF(y’ghc(2S)) = (4.7±0.9±3.0)×10-4 BESIII preliminary BF(y’gcc1)= 9.2±0.4% PDG y’ghc(2S) yield ≈ 0.005 y’-gcc1 yield Same M1 vs E1 suppression applies to bb _

  44. Summary -- open strange threshold -- _ • Strong evidence for KK-mediated a0(980) f0(980) mixing reported by BESIII • -below level expected for “pure” KK molecule picture • Large (≈20%) Isospin violation seen in h(1405)p0f0(890) decays • anomalous f0(980) width  influence of KK* threshold & Triangle Singularity • Properties of X(3872) consistent with expectations for DD* S-wave molecule-like state • - JPC=1++ favored (2-+ not ruled out)  mixing with cc1? • - Mass = MD0 + MD*0 to a part in ~104 • - no isospin partners are seen • - Isospin-violating X(3872)rJ/y is a strong decay mode • “ϒ(5S)”Zb1,2p- with Zbϒ(nS)p+ &Zbhbp+ a source of p+p-ϒ(nS) & p+p-hb(nP) at “ϒ(5S)” • - MZb1-( MB + MB* ) = +3.6 ±1.8 MeV; MZb2- 2MB* = +3.1 ±1.8 MeV • S-wave BB* and B*B* molecules?large widths to hidden beauty • First observation of hb(2S) • - DMhfs(2S) = 24.3±4.3 MeV Bf[hb(2P)ghb(2S)] = 47±13% preliminary • no surprises _ _ -- open charm threshold -- _ ‘ _ -- open beauty threshold -- + + + _ _ _ -- new from Belle --

  45. Signals for f0(980)pp & K+K- BESII PLB 607, 243 (2005) f’2(1525)+f0(1710)  K+K- f0(980)  K+K- strong f0(980) coupling to KK _ f0(980)  p+p- gKK gpp =4.2±0.3 f2(1270)+f0(1370)  p+p- f0(1790)  p+p- Bf(J/yff0(980) = 0.32±0.09 x 10-3

  46. Signal for a0(980)hp Signal for a0(980)K+K- Belle Collab: PRD 80, 032001 (2009) gghp0 Belle a0 Crystal Barrel Collab: PRD 57, 3860 (1998) hp0 a0(980)  K+K- a0(980) (hp0) a0(1320) (hp0) strong a0(980) coupling to KK gKK gph =1.03±0.14

  47. Thank you Obrigado 감사합니다

  48. p+p-system in X(3872)p+p-J/y comes from rp+p- Belle: PRD 84 052004 CDF: PRL 96 102002 rp+p- lineshape M(p+p- ) p+ r p- X3872 J/y M(p+p- )

  49. JPC of the X(3872) 1++ fits well with no adjustable parameters 2-+cannot be ruled out m+ qm J. Rosner PRD 70, 092023 (2004) for 1++: p- K c p+ CDF: PRL 98 132002 m- 1++ Belle: PRD 84 052004 2- + 1++ 2- + 1- - c2 =4.60 c2=0.56 O++ c2 =1.56 c2=5.24 2-+ has higher c2 and fewer dof than 1++

  50. _ 1++ cc assignment? cc1 ‘ pinned to: Mcc2=3930 MeV ‘ • Mass is too low? • 3872 vs 3905 MeV • nr=2 splitting> nr=1 • G(cc1 gy’) ~180 keV • G(cc1 g J/y) ~14 keV • G(cc1 gy’)/G(cc1 g J/y)>>1 • expt’l upper limit: <2.1 ‘ ‘ T.Barneset al PRD 72, 054026 • Gp+p-J/y=(3.4±1.2)GgJ/y ~45 keV huge for Isospin-violating decay c.f.: G(y’p0J/y)≈0.4 keV

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