1 / 53

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:

minerva-crane
Télécharger la présentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 Superseded by QCD in the 1970s:observed particles are color singlets color + complementary color  white white 3 primary colors  blue-yellow green-magenta red-cyan Λ=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

More Related