Hadron Spectroscopy with a variety of flavors

Transcription

1 Hadron Spectroscopy with a variety of flavors Toru Iijima Kobayashi-Maskawa Institute Nagoya University December 15, 2012

2 Quarks to Universe How quarks acquire their mass and form hadrons?

3 Quest in low-energy QCD Are there exotics beyond meson(qq) /baryon (qqq)? Sakata Model (p, n, Λ) Gell-Mann (u,d,s) 6 quark model I II III u c t up charm top d s b down strange bottom q=u, d, s, c, b, t flavor color (R,G,B) Ordinal Hadrons meson baryon New Hadrons(Exotics) Tetra-quark Penta-quark Molecule q q q q q QCD just require hadrons to be colorless, and allow exotics. Such exotic states exist? 3

4 Gell-Mann Existence of such exotics have long been discussed since the birth of the quark model.

5 Discoveries in 1974 Discovery of J/ψ SLAC, Burton Richter et al. BNL, Samuel Ting et al. c c And following qurkonium spectroscopy established physical existence of quarks and qq picture of mesons. 5

6 Discoveries at B-factories Discovery of X(3872) and other many XYZ states etc. Unexpected bonus of the B-factories Discoveries of new resonances at Belle Integrated luminosity (fb -1 ) X(3940), Y(3940) Y(4660) Y(4008) D sj (2860) D sj (2700) X cx (3090) Z(4430) Y(4320) χ c2 Y(4260) Σ c * baryon triplet X(3872) D 0 * 0 & D 1 * 0 D sj (2317/2460) η c & e + e - cccc 6 Z(4430) c u d c X(3872) u c u c

7 Charmonium-like Spectroscopy Above DD threshold? Below DD threshold well understood by VQCD 4 αs = + kr 3 r We do not understood yet how hadrons are formed from QCD. 7

8 XYZ at B Factories State Mass (MeV) Width (MeV) Decay Production Ys(2175) 2175±8 58±26 φf 0 ISR X(3872) ±0.33 <0.95 J/ψππ, J/ψγ B decay X(3872) / /-1.8 D *0 D 0, J/ψω B decay Y(3915) 3915±4 17±10 J/ψω γγ Z(3940) 3929±5 29±10 DD γγ X(3940) 3942±9 37±17 DD* Double-charm Y(3940) 3942±17 87±34 J/ψω B decay Y(4008) / /-80 J/ψππ ISR Z(4051) / /-28 πχ c1 B decay Tetraquark Di-quark u c c u D (*) D (*) Molecule X(4160) 4156± /-65 D*D* Double-charm Z(4248) / /-72 πχ c1 B decay Y(4260) 4264±12 83±22 J/ψππ ISR X(4350) / /-14 J/ψφ γγ c u π c u Y(4350) 4361±13 74±18 ψ ππ ISR Z(4430) ± /-18 ψ π B decay Y(4660) 4664±12 48±15 ψ ππ ISR Y b (10890) ± /-7.6 ππυ(ns) e + e - annihilation Z b (10610) ± ±2.5 (Υ(nS) or h b ) π Υ(5S) /Y b decay Z b (10650) ± ±3.2 (Υ(nS) or h b ) π Υ(5S) /Y b decay Hybrid c c g g 8

9 The KEKB Collider SCC RF(HER) ARES(LER) e Belle detector - (8.0GeV) e + (3.5GeV) Υ(4S) BB Lorentz boost: βγ = Finite crossing angle - 11mrad 2 Operated Ares RF cavity e + source Peak luminosity 2.1 x cm -2 s -1! 2010/10/29 Toru Iijima, seminar at Konan 9

10 Luminosity at B Factories L >1ab Belle 10

11 Belle Detector Acceptance: 0.9 4π Vertex resolution s(j/ψ ll) ~75nm Momentum resolution σ(pt) = 0.19 Pt 0.34/β % Energy resolution σ(eγ)/eγ 1GeV Particle ID e, µ, π, K, p Minimum bias trigger Evis >= 1GeV & Ntrk >= 2 & Ncluster >= 4 essentially no loss for BB. 11

12 Production of cc in B Factories B factories can produce charmonium (-like) states in four ways. 12

13 World-wide Activity BES III CLEO Results are mainly from Belle for this talk

14 Chamonium-like Exotics 14

15 X (3872) Discovery by Belle in 2003, followed by D0, CDF, BaBar. (90%CL) 15

16 X(3872) at LHC CMS (40 pb -1, s = 7 TeV) R σ(pp X(3872) +K ) Br(X(3872) J /ψ π + π ) σ( pp ψ(2s) +K ) Br(ψ(2S) J /ψ π + π ) = ± ± LHCb (34.7 pb -1, s = 7 TeV) σ(pp X(3872) +K ) Br(X(3872) J /ψ π + π ) = [4.7 ±1.1 ± 0.7] nb CMS PAS BPH arxiv: M X (3872) = [ ± 0.48 ± 0.12]MeV Looking forward to results with >1fb -1 data. 16

17 J PC of X(3872) CDF(780pb -1 ) PRL 98, (2007) Belle (711fb -1 ) PRD 84, (2011) BaBar (420fb -1 ) PRD 82, (2010) All J PC values other than 1 ++ or 2 -+ are ruled out with high confidence. Need more statistics to distinguish 1 ++ vs 2 -+.

18 Properties of X(3872) C = +1 X(3872) J/ψ γ, J/ψ ρ seen J PC = 1 ++ or 2 -+ Angular distribution I = 0 No charged partner so far isospin violating decay X(3872) J/ψ ρ (π + π - ) Mass just around D*D Possible interpretation Conventional cc : c c1 (2 3 P 1 ) for 1 ++, h c2 (1 1 D 2 ) for 2 -+ Exotics: D *0 D 0 molecule : Tetra-quark : M X M D *0 M D 0 = 0.12 ± 0.35 MeV M X M D *+ M D = 7.74 ± 0.35 MeV [cq ][c q] [cq][c q ] 18 D *0 D 0 molecule Tetra-quark

19 Z(4430) +, Z (4050) +, Z(4250) + by Belle Belle found Z(4430) + in B K π + ψ decays. One-dimensional fit on ψ π + distribution after K*(890) /K*(1430) vetos. PRD80, (2009) Confirmed by analysis with a full Dalitz plot. +15 M = ( Γ = ( )MeV /c )MeV PRD80, (2009) Belle found also another two states, Z(4050) + & Z(4250) +, in B K π + χ c1 decays. M 1 = (4051± )MeV /c Γ 1 = ( )MeV +44 M 2 = ( Γ 2 = ( )MeV /c )MeV M 2 (ψ π + ) Their minimum quark content must be exotic: cc ud 19

20 Bottomonium-like Exotics 20

21 Anomalies in ϒ(5S) decay Mass, GeV/c ϒ(11020) ϒ(10860) 260 2M(B) ϒ(4S) 2 ϒ(3S) η ϒ(2S) b (2S) π + π 330 h b (2P) 190 h b (1P) Γ[ϒ(5S) ϒ(1,2,3S) π + π ] >> Γ[ϒ(4,3,2S) ϒ(1S) π + π ] h b production h b (1P) Belle PRL100,112001(2008) h b (2P) 9.75 partial Γ(keV) ϒ(1S) η b (1S) J PC -+ = Belle PRL108,032001(2012) ϒ(5S) h b (1,2P) π + π are not suppressed Expect suppression Λ QCD /m b Heavy Quark Symmetry Violation 21

22 Anomalies in ϒ(5S) decay ϒ(11020) ϒ(10860) Mass, GeV/c M(B) 260 η b (2S) 430 π ϒ(4S) 2 ϒ(3S) 1 ϒ(2S) + Z b π + h b (2P) h b (1P) h b production via intermediate charged states Z b 9.75 partial Γ(keV) ϒ(1S) η b (1S) J PC -+ = ϒ(5S) h b (1,2P) π + π are not suppressed Expect suppression Λ QCD /m b Heavy Quark Symmetry Violation 22

23 h b (1P, 2P) π + π - h b (1P) π + h b (2P) π + M miss (π) Fit with to look at h b π + A(Z + b1 ) + A(Z + b 2 ) + A(NR) Two peaks at the positions same as ϒ(nS)π + π 23

24 Charged Bottomonium-like Z b + in ϒ(nS)π + Two peaks at the same positions in the 3 modes. ϒ(1S) ϒ(2S) ϒ(3S) Two resonances: Z b+ (10510), Z b+ (10560) 24

25 Z b (10610) & Z b (10650) M= ±2.0 MeV M= ±1.5 MeV Γ=15.6±2.5 MeV Γ=14.4±3.2 MeV 25

26 Molecular Explanation of Z b + Bondar et al, PRD84,054010(2011) Proximity to thresholds favors molecule picture Z b+ (10510) Z b+ (10560) Each of them is mixture of spin triplet and singlet bb u u B - This model explains B *- Why h b is unsuppressed relative to Relative phase ~0 for and ~180 0 for h b Production rates of Z b (10610) and Z b (10650) are similar widths If Z b + is B*B (*) molecule, it should decay into B*B (*) 26

27 Study of Z b B*B (*) For the ϒ(5S) B*B(*) π + channel: _ Fully reconstruct one B meson in five exclusive decay modes. Look at recoil mass of Bπ (for missing B) rm(bπ) and of the pion (for two B combination) rm(π). 27

28 Clear BB*π and B*B*π signals Full reconstruction of one B in 5 modes M(B) M miss (Bπ) recoil mass Select two peaks _ BB*π _ BBπ _ B*B*π preliminary BF[ ϒ(5S) B ( * ) B ( * ) π ] _ fb -1 _ BB _ <0.60 % at 90% C.L. BB* + _ BB* (4.25 ± 0.44 ± 0.69) % B*B* (2.12 ± 0.29 ± 0.36) % significance 9.3σ 5.7σ 28

29 Observation of Z b BB* and Z b B*B* Z b 8σ phsp _ M (BB*) _ M (B*B*) Z b 6.8σ phsp Z b? Z b BB* is suppressed w.r.t. B*B* despite larger PHSP Molecule admixture of _ BB* in Z b is small Assuming Z b decays are saturated by these channels: arxiv:

30 Fit ϒ(2S)π 0 π 0 structure arxiv: Dalitz plot analysis with Z b s without o Clear Z 0 b signals are seen in ϒ(2S)π 0 π 0 o Significance of Z b0 (10610) is 5.3σ (4.9σ with systematics) o Z b0 (10650) is less significant (~2σ) o Fit gives M(Z b0 (10610) ) =10609±8±6 MeV cf: M(Z b+ )= ±2.0 MeV 30

31 H-Dibaryon Belle CLEO s observation: Br(Υ(1S) d + anything)=3x10-5 large! Belle has ( ) x 10 6 Υ(1S+2S) Talk by Bong Ho Busan New Hadron WS (Nov.19-21, 2012)

32 Search Results Br (Υ(1S,2S) H + X ) < 90%CL.

33 Future Prospects 33

34 SuperKEKB/Belle II Lpeak=8x10 35 cm -2 s -1 Higher beam currents Smaller beam size Lint = 50ab -1 (goal) Nano-beam crossing O(10 4 ) X(3872) New beam pipes & bellows e- 2.6 A e+ 3.6 A Reinforced background immunity Improved performance GRID-based computing Improve beam monitors and control system e+ Damping ring Reinforce RF systems for higher beam currents New positron capture section Low emittance electron gun

35 SuperKEKB / Belle II Construction New beam pipe in stock Construction of e+ dumping ring QC1LE prototype Installation of new magnets Belle II waiting for installation Beam test of new PID Beam commissioning: Physics run: 2016-

36 Final Remarks 36

37 Summary of this talk Low energy QCD is one of the least understood area of the SM. High luminosity B factories have brought many discoveries of new hadronic states, especially the quarkonium-like exotics Recent discoveries in bottomonium region (Molecular picture seem to be favored.) More data are expected Other exotics states: H dibaryon, pentaquark (including heavy flavor), T cc (ccud) New data from LHC, SuperKEKB, Collaboration w/ lattice QCD is essential. Impact on Astro-particle physics and cosmology.

38 New Hadron Grant-in-aid for innovative scientific research area Elucidation of new hadrons with a variety of flavors.

39 Crossover Low energy QCD is one of the least understood part of the SM, and makes a developing interdisciplinary area. Crossover is important Particle Physics Collider Phenomenology (Model) Nuclear Physics Fixed target Lattice QCD Crossover workshop 新ハドロン x 素核宇宙融合 X HPCI- 分野 5 RIKEN AICS Nagoya

40 Hadron 2013 (XV International Conference on Hadron Spectroscopy) in Nara (Nara Prefecture New Public Hall ) Co-chairs: Atsushi Hosaka (RCNP, Osaka) Toru Iijima (Nagoya) Kenkichi Miyabayashi (Nara) About 200 participants Main topics include Spectroscopy of light- and heavy-quark mesons Baryons Quarkonia Glueballs, hybrids, and multiquarks Phenomenological models Effective field theories QCD on the lattice Hadron structure Hadrons in matter Heavy-ion collisions Future facilities

41 Thank you!

42 Backup Slides

43 Z + (cont d) BaBar does not confirm Z+ s Z(4430) + search in B Kπ + ψ Z(4050) + /Z(4250) + search in B Kπ+χ c1 Excess is < 2σ w.r.t. Kπ reflection. But, do not rule out Belle s results. UL is statistically compatible with Belle results Br(B 0 Z + K ) Br(Z + π + ψ'/ χ c1 ) PRD79, (2009) PRD85, (2012) Belle BaBar BaBar U.L. Belle Z(4430) + < 3.1 (95%CL) 4.1 ± 1.0 ± 1.4 Z(4050) + < 1.8 (90%CL) Z(4250) < 4.0 (90%CL) Note: In the BaBar analyses, Z + amplitudes are added Incoherently, therefore, interference effects are not included. They are included in the Belle analyses (see S.Olsen s summary talk at CHARM2012, and also backup). 43

44 Exotics in light flavors? e + e - ISR : Y(4260) π + π J/ψ; Y(4360) π + π ψ Y(2175) π + π φ (f 0 φ) γγ (two-photon) seen by BaBar, Belle, BES III X(3915) ω J/ψ; X(4350) φ J/ψ What about ωφ, φφ? 44

45 γγ VV(ωφ, φφ, ωω) 870 fb -1 near Υ(nS)[n=1, 5] 4 charged tracks + π 0 ; φ K + K -, ω π + π - π 0 Signals are extracted by fitting distribution for each M(VV) bin. η c χ c0 χ c2 Obvious structures in low M(VV) region. J P of the structure is extracted from angular distributions. Phys. Rev. Lett. 108, (2012) 45

46 Maximum CM energy at SuperKEKB Want s 12GeV to explore bottomonium spectroscopy. Present attainable E max = GeV; limited by e - linac, e + BT magnet, QC1E quench limit. Study possibility of ramping up HER 8.6 GeV, for example, by S-band linac C-band.

47 Preliminary Upper Limit

48 International Cooperation LEPS2 Super-KEKB J-PARC GSI/FAIR JLAB LHC BEPCI I RHIC J-LAB