Nonstandard hadrons -- a few comments--

Transcription

1 News from BES III Nonstandard hadrons -- a few comments-- Stephen Lars Olsen Daejeon, KOREA Bound States in QCD and Beyond II, Schlosshotel Rheinfelt, St. Goar, Germany, Feb 20-23, 2017

2 Ich weiss nicht, was soll es bedeuten, Light quark sector Neutral charmonium-like X(3915) Y(4260) Charged charmonium-like Hidden-charm pentaquarks b-quark sector

3 What is the X(3915)??

4 B!KωJ/ψ decays B meson c c ω J/ψ π + π 0 π - compute π + π - π 0 invariant mass s q!k ω!π + π - π 0

5 M(ω J/ψ) X 3915!ωJ/ψ peak near ω J/ψ mass threshold X(3915) X 3915!ωJ/ψ B ±!K ± ωj/ψ B 0!K S ωj/ψ Belle PRL94, (2005) BaBar PRL101, (2008) Some discrepancy in M & Γ; general features agree

6 Also seen in γγ!ωj/ψ X ω J/ψ γγ! ωj/ψ Belle PRL104, (2010) M=3915 ± 5 MeV Γ= 17 ± 11 MeV M(ωJ/ψ) BaBar PRD86, (2012) γγ! ωj/ψ M=3919± 3 MeV Γ= 13 ± 7 MeV M(ωJ/ψ)

7 BaBar measurements determine J PC =0 ++ θ l * n θ l * θ ln BaBar PRD 86, (2012)

8 X(3915)! DD is not seen B!Kψ(3770)!D 0 D events No signal near 3915: Signal yield / 20 MeV/c B!KD 0 D 0 J. Brodzicka et al. (Belle) PRD 100, MeV <10 events M(D 0 D 0 ) (GeV/c 2 ) Γ(X(3915)!DD) <1 MeV charmonium theory: Γ(χ c0!dd) = 30 MeV

9 What is the X(3915)?

10 X(3915) = χ c 0 charmonium state? χ c0 = 2 3 P 0 cc state

11 If X(3915) = χ c0 : X(3915) = χ c 0 charmonium state? χ c0 = 2 3 P 0 cc state? - mass is to high: M(χ c2 )-M(χ c0 ) 9 MeV 1/15 th the n=1 splikng: M(χ c2 )-M(χ c0 )=141 MeV X(3915) M=3918 ± 2 MeV M=3927 ± 3 MeV ΔM=9 MeV

12 If X(3915) = χ c0 : X(3915) = χ c 0 charmonium state? χ c0 = 2 3 P 0 cc state? - mass is to high: M(χ c2 )-M(χ c0 ) 9 MeV 1/15 th the n=1 splikng: M(χ c2 )-M(χ c0 )=141 MeV - X(3915)!DD not seen? theory predicts: Γ(χ c0!dd) 30 MeV my esmmate: Γ(X(3915)!DD) < 1 MeV X(3915) -Γ(χ c0!ωj/ψ) > 1 MeV, too large for an OZI-suppressed charmonium transimon.

13 Γ(χ c0! ωj/ψ)>γ(χ c0!dd)?? χ c0! ωj/ψ is OZI-suppressed no connecmng quark lines χ c0 c ω π + π 0 π - J/ψ c gluons c c χ c0 c c χ c0! DD is OZI-allowed c q q (=u or d) q c D D OZI suppressed modes are expected to be much smaller than OZI allowed modes

14 If X(3915) χ c, what is it? 0 X(3915)!ωJ/ψ violates OZI-rule unless it s a 4-quark state Mass is near 2m Ds threshold: M(X(3915)) = 2m Ds -18 MeV X(3915)!DD decays are suppressed: Γ(X(3915)!DD) < 1 MeV

15 Possibilimes D s -D s molecule? Li & Voloshin, PRD 91, [cs][cs] tetraquark? Lebed & Polosa, PRD 93, cc hybrid? D S s D s C s C s C L=0 s C C g C what binds it? why not X!ηη c? too light for 0 ++ cc-hybrid

16 0 ++ not a good match for a light hybrid?? M (MeV) ~500 MeV X(3915) m π 400 MeV Liu, et al (Had Spec Collab) JHEP07,126

17 X(3915)!ηη c? c s c s c c s s η χ η only OZI-allowed mode for a [cs][cs] tetraquark (or a D s D s molecule) Vinokurova et al (Belle) JHEP06,132 plus erratum Events/5 MeV/c a) B!Kηη c ; η!γγ Belle b) B!Kηη 4 c ; η!π + π - π 0 Events/5 MeV/c 2 3 Belle M(η c η), GeV/c M(η c η), GeV/c 2 Bf (X ηη c ) Bf (X ω J /ψ ) <~2

18 Where is the χ c 0? J /ψ e + e J /ψ DD 2007: 693 ~ -1 in Belle D D M = 3878 ±78 MeV Γ = MeV signif: 3.8σ (stat.) 49 MeV below M(χ c2 ) Pakhlov et al (Belle) PRL100, M(DD) See also K.T. Chao PRB661,348

19 Where is the χ c 0? J /ψ e + e J /ψ DD 2007: 693 ~ -1 in Belle D D M = 3878 ±78 MeV Γ = MeV signif: 3.8σ (stat.) 49 MeV below M(χ c2 ) Pakhlov et al (Belle) PRL100, M(DD) See also K.T. Chao PRB661,348

20 What is the X(3915)? It is not a good candidate for the χ c0 stay tuned for soon-to-be-released Belle results If it is a D s D s (2420) molecule: B.E. 18 MeV " need a binding mechanism to produce this If it is a cc-gluon hybrid: current (m π 400 MeV) LQCD mass calculamon off by 500 MeV! If it is a [cs][cs] QCD tetraquark: the X(3915)!ηη c decay mode should show up soon It remains an intriguing puzzle

21 The Y(4260)

22 What is the Y(4260)? Y(4260) prod. mode ensures J PC = all the J PC = charmonium states below M=4500 MeV have already been assigned

23 found by BaBar in e + e -! γ ISR π + π - J/ψ σ(e + e -! hadrons) E cm (GeV)

24 found by BaBar in e + e -! γ ISR π + π - J/ψ σ(e + e -! hadrons) α σ(e + e -! π + π - J/ψ) BaBar PRD86, Y(4260) E cm (GeV) M(π + π - J/ψ) (GeV)

25 Y(4260)! π + π - J/ψ confirmed by Belle e + e -!γ ISR π + π - J/ψ Belle PRL99,

26 Y(4260)! π + π - J/ψ confirmed by Belle e + e -!γ ISR π + π - J/ψ Belle PRL99, PDG-2016: no sign of Y(4260)! D (*) D (*) Y(4260) peak in σ (π + π - J/ψ) occurs at a dip in σ(d (*) D (*) ) e + e -!hadrons 4250 MeV M(π + π - J/ψ) (GeV) Γ(π + π - J/ψ) is large, but should be OZI suppressed if cc BESII PRL88, E cm (GeV)

27 resonances in e + e -! γ ISR π + π - ψ BaBar: another one in π + π - ψ (not the Y(4260)) Belle: confirms the Y(4360) & finds 4660 a) e + e -!γ isr π + π - ψ b) e + e -!γ isr π + π - ψ BaBar Y(4260) PRL Belle PRL M(π + π - /ψ ) (GeV/c 2 ) M(π + π - /ψ ) (GeV/c 2 ) PDG-2016: PDG-2016:

28 BEPCII/BESIII as a Y(4260) factory

29 Y(4260) in BESIII & Belle # ~1500 Y(4260) events ~1 month s BESIIII data BESIII PRL 100, ~500 Y(4260) events ~10 year s Belle data Belle PRL 100, σ Ecm 2 MeV σ Ecm 5 MeV

30 Other Y(4260) decay modes?

31 e + e -! π + π - J/ψ Dalitz plot BESIII PRL 100,

32 e + e -! π + π - J/ψ Dalitz plot BESIII PRL 100, M 2 (π + J /ψ ) (GeV/c 2 ) 2

33 e + e -! π + π - J/ψ Dalitz plot BESIII PRL 100, M 2 (π + J /ψ ) (GeV/c 2 ) 2 Y 4260 Z c π + Z c!πj/ψ signal π - reflecmon Y(4260) π ± Z c (3900) π J /ψ

34 e + e -! π + π - J/ψ Dalitz plot BESIII PRL 100, M 2 (π + J /ψ ) (GeV/c 2 ) 2 π + Z c!πj/ψ signal Y(4260) f 0 (980)J /ψ π + π Y 4260 π + f 0 f 0!π + π - π - π - Y 4260 Z c reflecmon J/ψ J/ψ Y(4260) π ± Z c (3900) π J /ψ

35 Radiamve decays? Y(4260)!γ π + π - J/ψ? E cm = 4009 MeV 3872 MeV E cm = 4220 MeV 3872 MeV 0 evts 10 evts 4251 MeV E cm = 4260 MeV E cm = 4360 MeV 9 evts 2 evts MeV assuming Bf(X 3872!π + π - J/ψ)=5%: Bf (Y 4260 γ X 3872 ) Bf (Y 4260 π + π J /ψ ) 0.1 "not small!! some commonality between X(3872) & Y(4260)?

36 Y(4260)!ωχ c0?? M ωχco = 4230±10 MeV/c 2 Γ ωχc 0 = 38 ±12 MeV mass threshold 4250 MeV

37 Y(4260)!ηJ/ψ? 4250 MeV BESIII ηj/ψ PRD91,112005

38 Y(4260)!π + π - h c?? What is the h c? J PC =1 +- BESIII γ M hads e a) + e π + π γ η c BESIII b) e + e π + π γ η c BESIII hads h c γη c m hc m ηc η c hads 15 exclusive modes M(γη c ) M(γη c ) (GeV/c 2 )

39 e + e -!π + π - h c e + e π + π h c low-lum. scan data e + e π + π h c high-lum. data BESIII PDG 2016 Ψ(4415): M = 4421 ± 4 MeV Γ = 62 ± 20 MeV

40 e + e -!π + D 0 D* - BESIII preliminary PDG 2016 Ψ(4415): M = 4421 ± 4 MeV Γ = 62 ± 20 MeV

41 The Y(4260) is not a single BW resonance! BW res. fit preferred over 1 BW res. fit by >7σ

42 Y(4260): mass! lower & width! narrower pre-2017 post-2017 PDG-2016: -31 MeV ⅓ Y(4220) decay modes: - π + π - J/ψ $ πz c (3900) $ f 0 (980) J/ψ - π + π - h c - ωχ c0 - ηj/ψ - γx(3872) - πdd*

43 Y(4260): mass! lower & width! narrower pre-2017 post-2017 what is the 2 nd peak? PDG-2016: -31 MeV ⅓ Y(4220) decay modes: - π + π - J/ψ $ πz c (3900) $ f 0 (980) J/ψ - π + π - h c - ωχ c0 - ηj/ψ - γx(3872) - πdd*

44 Y(4260): mass! lower & width! narrower pre-2017 post-2017 what is the 2 nd peak? Y(4360)?? PDG-2016: -31 MeV ⅓ Y(4220) decay modes: - π + π - J/ψ $ πz c (3900) $ f 0 (980) J/ψ - π + π - h c - ωχ c0 - ηj/ψ - γx(3872) - πdd* δm -1.8σ spot on Y(4320) decay modes: - π + π - J/ψ - π + π - ψ??

45 What is the Y(4260)?

46 some proposed models DD 1 (2420) molecule actually: Y(4260) = 1 2 DD (2420)± D (2420)D 1 1 QCD cc-gluon - hybrid QCD diquark-dianmquark tetra-quark hadrocharmonium

47 Models for the Y(4260) I Molecule? Ding PRD 79, Wang, Hanhart & Zhao PRL 111, Cleven, Wang, Guo, Hanhart, Meissner & Zhao PRD 90, D 1 (2420) J P =1 + M= ± 0.6 MeV Γ= 27.4 ± 2.5 MeV Decay: D 1 (2420)!D*π Y(4260) B.E. 66 MeV ~66 MeV pre-2017: BE 35 MeV

48 cc-gluon hybrid? Models for the Y(4260) II Zhu PLB 625, 212 Close & Page PLB 628, 215 Kou & Pene PLB 631, 164 D D * J= LQCD calc. (m π 400 MeV): Lowest cc-gluon hybrid: M=4285 ± 14 MeV pre-2017: too high by ~35 MeV post-2017: too high by ~65 MeV Had. Spectr. Collab. JHEP07, 126 D 1 (2420)! D*π very broad hard to see D 0 (2400)! Dπ D 0 (2400) J P =0 + M=2318 ± 29 MeV Γ= 267 ± 40 MeV Decay: D 0 (2400)!Dπ Y(4260) B.E. 100 MeV ~100MeV

49 1 - - hybrid?? only one? M (MeV) Y(4260) m π 400 MeV

50 Models for the Y(4260) III QCD tetraquark? Maiani et al. PRD 89, L=1 excitamon of the X(3872): - naturally accounts for large Y(4260)!γX(3872) as an allowed E1 transimon X(3872): S=1 bad diquark q C L=0 ΔL=1 ΔM=350 MeV Y(4260): S=1 bad diquark q C L=1-350 MeV is a typical mass penalty for ΔL=1: L=1 L=0 δm (MeV) D 1 (2420) D * (2010) 410 D s1 (2460) D s (2110) 350 h c (3525) J/ψ 430 S=0 good diquark q C S=0 good diquark q C

51 Models for the Y(4260) IV Hadrocharmonium? Dubynskiy & Voloshin, PLB 666, 344 Li & Voloshin, Mod. Phys. Le. A29, color-singlet charmonium core (for Y(4260) this a J/ψ + h c mixture) surrounding color-singlet cloud of light quarks & gluons C C charmonium core & light-quark gluon cloud are coupled via Van-der-Waals like color field forces Y(4260)! J/ψ (or h c )+ light-hadrons decays should be dominant, --- decays to other charmonium states are suppressed

52 Tesmng Y(4260) models against data - DD 1 (2420) molecule: expect a strong Y(4260) affinity for DD 1 (2420)-like final states - cc-gluon hybrid: expect a strong Y(4260) affinity for D*D 0 (2400)-like final states - QCD tetraquark models: expect partner states, including charged partners (likewise for the X(3872)) Y - (I=1;I z =-1) ± Y + (I=1;I z =+1) - hadrocharmonium model: +: Y 0 (I=1;I z =0) -: Y 0 (I=0;I z =0) expect Bf(Y(4260)!ππ J/ψ) >> Bf(Y(4260)!ω χ c0 )

53 e + e E cm =4260 MeV Dalitz plot 2 M D1 (2420) the top edge of the Dalitz plot barely grazes the low-mass tail of the D1(2420) % D 1 (2420)D (!D*D) % πz c (3900) (!D*D) % Data X.P. Xu, BESIII Anal Memo 91 -(M D1 +Γ/2) 2 -(M D1 -Γ/2) 2

54 e + e E cm =4260 MeV Dalitz plot 2 M D1 (2420) the top edge of the Dalitz plot barely grazes the low-mass tail of the D1(2420) % D 1 (2420)D (!D*D) % πz c (3900) (!D*D) % Data X.P. Xu, BESIII Anal Memo 91 -(M D1 +Γ/2) 2 -(M D1 -Γ/2) 2 no clustering of data events at the top of the DP

55 Need high-stamsmcs DP distribumons M 2 D 1 D Y4260 θ πd π D* Y(4260)= DD 1 (2420) molecule prediction Cleven, Wang, Guo, Hanhart, Meissner & Zhao PRD 90,

56 Partner states? ± Y - (I=1;I z =-1) Y + (I=1;I z =+1) +: Y 0 (I=1;I z =0) I=1, states have not been seen need to look at π J/ψ or πψ -: Y 0 (I=0;I z =0) Y(4260)? (same for X(3872). BaBar & Belle searches for B!K X ± ; X ±! ρ ± J/ψ found nothing): B K π + π J /ψ Belle B K ± π π 0 J /ψ Belle PRD 84, M(π + π J /ψ ) M(π π 0 J /ψ )

57 Bf(Y(4260)!ππJ/ψ) vs Bf(Y(4260)!ωχ c0 ) e + e π + π J /ψ e + e ωχ c0 Y(4260) ωχ c0 Y(4260) π + π J /ψ Bf (Y(4260) π + π J /ψ ) Bf (Y(4260) ωχ c0 ) within a factor of 2 Bf (Y(4260) π + π J /ψ ) Bf (Y(4260) ωχ c0 ) not the case

58 What is the Y(4260)? The Y(4260) mass is lower and width narrower than previously thought Y(4260)! Y(4220)? If it is a DD 1 (2420) molecule: B.E. 66 MeV affinity to DD 1 (2420) should be high If it is a cc-gluon hybrid: its mass is ~65 MeV below current (m π 400 MeV) LQCD predicmons affinity to DD 0 (2400) should be high If it is a QCD diquark dianmquark tetraquark: it should have Isospin- & SU F (3)-mulmplet partner states a quantitative test of this is in progress hard to identify; tests are in progress If it is hadrocharmonium: decays to non-j/ψ(h c ) charmonium states should be suppressed none seen (so far) they aren't BESIII is well suited to further invesmgate this intriguing puzzle a "Y(4260)" factory

59 Ich glaube, die Daten verschlingen am Ende Theoremker und Theorien; Und das hat mit ihrem Singen Die Lorelei getan.

60 Acknowledgement With fond memories of Herr Marx, my Brooklyn Tech H.S. German teacher, who drummed Heine s poetry into my dull, teen-aged head --- and belated, but sincere apologies for all the grief my classmates and I caused him.