New CLEO Results on Charmonium Decays

Transcript

1 New CLEO Results on Charmonium Deays Brian Heltsley on behalf of the CLEO Collaboration 6th International Workshop on Heavy Quarkonia Nara, Japan Deember 2008 B. Heltsley QWG Deays 1

2 Radiative Charmonia Deays Simplest onia deays J/ψ γ γ γ η γ γ χ J γ γ Next simplest J/ψ γ gg ψ(2s) γ gg New for QWG! J/ψ χ J γ (ρ 0, ω, ϕ) η Properties from J/ψ γ η _ η, χ 0,2 _ J/ψ, ψ(2s) _ γ γ γ γ γ g g B. Heltsley QWG Deays 2

3 J/ψ 3γ & η γγ Measure or limit the deay J/ψ 3γ Expet B( J/ψ 3 γ ) ~ B < Crystal Ball (1980) No partile ever observed in a 3γ3 deay! B( ω 3 γ ) < B( Z 3 γ ) < However, ortho-positronium (o-ps), the 3 S 1 e + e - atom, deays nearly 100% to 3γ. 3. Also, B(o-Ps Ps 5γ) 2 x 10 6 Seek η γ γ in radiative J/ψ deays & measure B( J/ψ γ η ) B( η γ γ ) E760 & E835 have observed η γ γ in pp γ γ Belle: 4.1σ evidene in B ± K ± γγ B( η γ γ ) = ( ) 10 4 [PLB 662 (2008) 323] B. Heltsley QWG Deays 3

4 J/ψ 3γ π + J/ψ γ 1 γ 2 γ 3 ψ(2s) Unique topology: 2 traks provide a tag of the J/ψ 3 showers with no resonant substruture Impose 4-momentum onservation χ 2 of kinemati fit a key variable Suppress feed- down from other deays Also seek J/ψ γ η, η γ γ B. Heltsley QWG Deays 4 π

5 J/ψ 3γ Largest photon pair mass MC Smallest photon pair mass MC π 0 π 0 MC Plot has χ 2 <3 ut in plae Veto on masses inside , 0.16, , 0.60, , & >2.8 GeV 37 events remain in the data outside these regions B. Heltsley QWG Deays 5

6 J/ψ γ π 0 π 0 feed-down down Only happens if BOTH π 0 s deay asymmetrially Demand 4-momentum 4 onservation to suppress: χ 2 /dof < 3 for signal BRs for various J/ψ γ f J not well known Notie that SHAPES of all 5γ χ 2 distribution are similar The data an be used at large χ 2 /dof (5-20) for bgd normalization Mix of bgd soures does not to matter muh for leakage into χ 2 <3 B. Heltsley QWG Deays 6

7 PRL 101, (2008) Result for J/ψ 3γ Normalize γ f j bakground in χ 2 =5-20 region Small non-j/ J/ψ bgd from π + π - reoil sidebands After normalized bgd subtration Signal shape required to desribe data at small χ 2 Net yield evts -6.0 B = (12 ± 3 ± 2) x σ signifiane B. Heltsley QWG Deays 7

8 η γ γ B. Heltsley QWG Deays 8

9 η γ γ Seletion Largest photon pair mass γπ 0 Signal region γη MC γη MC MC 2 signal events 0.8 events bgd total Eff=10.9% Soure # bgd γ η 0.3 γ η 0.2 3γ 0.3 Total Smallest photon pair mass B. Heltsley QWG Deays 9

10 η γ γ Result B( J/ψ γ η ) x B( η γ γ ) = ( ± 0.3 ) x 10 6 or <5.3 x 10 Using CLEO s B( J/ψ γ η ) = ( 1.98 ± 0.09 ± 0.30 )%, B( η γ γ ) =( ± 0.1 ) x 10 4 PDG08 value = ( Consistent within 1.1σ < 2.6 x ) x 10 4 PRL 101, (2008) B. Heltsley QWG Deays 10

11 ψ(2s) γ χ χ γ γ 1 J, J B. Heltsley QWG Deays 11

12 ψ(2s) γ χ 1 J, χ J γ γ Shown@QWG5: H. Mahlke Striking experimental signature: only 3γ 3! In R Γ 2 (γγ)) / Γ 0 (γγ)) many theo.. & exp. unertainties will anel 1 st deay-based msmt Lowest order: R= st order α S : R=0.12 PRD78, (R) (2008) e + e - γγγ CLEO B. Heltsley QWG Deays 12

13 J/ψ γ gg B. Heltsley QWG Deays 13

14 J/ψ γ gg Selet lean primary γ s z γ E γ / E beam : z γ >0.3 veto γ s s that pair with another to form π 0 do not veto η γγ (too muh signal killed) Eliminate e + e - ontinuum bgd,, partly ISR, by using ψ(2s) (2S) π + π - J/ψ Makes analysis muh simpler than ϒ γ gg [PRD74, (2006)] Small non-j/ J/ψ bgd diretly subtrated with π + π - reoil mass sidebands Model remaining bgd in 3 systematially omplementary ways Two are data-driven, driven, one MC-only See paper for details Spread among them indiative of syst.. error Model signal as Three 2-body 2 proesses: γη, γη, γη(1440) Theoretial shape validated with CLEO ϒ γ gg measurements NEW: also inlude z γ -osθ γ orrelation & shape a la Koller-Walsh [NP B140, 449 (1978)]. Bakground Shapes Signal Spetrum Z γ 3 bgds differ mostly at large z γ where bgd is smallest osθ γ B. Heltsley QWG Deays 14

15 Signal Shape These are spetra developed for ϒ γgg PRD 69, (2004); PRD 72, (2005); PRL 96, (2006). PL 133B, 248 (1983). Found to work adequately for J/ψ γ ψ γgg z γ B. Heltsley QWG Deays 15

16 J/ψ Diret Photon Spetrum Data with 3 different bgd subtrations ϒ(1S) shape with arbitrary normalization Garia-Soto hep-ph/ Predition for J/ψ γgg Large Color Otet ME Small Color Otet ME Do not desribe using bgd 1 CLEO data using bgd 2 using bgd 3 After orreting for angular aeptane & effiieny, this spetrum gives # J/ψ γgg events # J/ψ ψ ggg from # π + π - J/ψ # J/ψ γgg J/ψ e + e -, µ + µ - (PDG) J/ψ γ * qq (PDG) PRD 78, (2008) B. Heltsley QWG Deays 16

17 Measured R γ & QCD Systemati error (11%) dominated by Bakground subtration unertainty Signal shape unertainty Brodsky, Lepage, Makenzie PRD 28, 228 (1983) predit Also an be expressed as B(J/ J/ψ γ gg) ) = ( 9.0 ± 1.0 ) % Somewhat larger than Voloshin [PPNP 61, 455 (2008) ] estimate of 6.7% based on α S (m )=0.19 & known Γ ee (J/ψ) B. Heltsley QWG Deays 17

18 ψ(2s) γ gg B. Heltsley QWG Deays 18

19 ψ(2s) γ gg Similar approah, but Must subtrat spetrum from below-ψ(2s) ontinuum data to suppress ISR effets Must subtrat ontribution from J/ψ γ ψ γgg & its bgd Use shape from dipion tags: ψ(2s) (2S) π + π - J/ψ Corret for ε, B(any J/ψ) ) / B +- FSR from MC Model remaining bakgrounds 3 different ways (both MC and data- driven methods) π 0 Bgd Lumi-saled ontinuum data ψ(2s) Data π + π - J/ψ from data FSR PRELIMINARY PRELIMINARY B. Heltsley QWG Deays 19

20 Results for ψ(2s) γ gg Integrate data for z γ >0.4 spread among bgd methods indiates systematis Corret for ε Corret for z γ <0.4 / z γ >0.4 ~30% of spetrum is z γ <0.4 Σ B[ ψ(2s) e + e -, µ + µ -, τ + τ - (PDG) γ * qq (PDG) π + π - J/ψ, π 0 π 0 J/ψ, η/π 0 J/ψ γη γ χ J, γ η, π 0 h 87%. 87%. Leaves ~13% for γ gg,, 3g We know total #ψ(2s)# B( γgg ) 0.9 % B( ggg ) 12 % PRELIMINARY R γ = ± ± ~Half of J/ψ R γ (~3σ below) Reminder: for ϒ(1S,2S,3S) γgg, CLEO measurements yielded R γ 0.03 within ~10-15% errors [ PRD74 (2006) ] B. Heltsley QWG Deays 20

21 Charmonium Annihilation Summary B. Heltsley QWG Deays 21

22 Many measured annihilation rates! CLEO has measured several important & fundamental rates Various ratios an be taken to anel out wave funtion terms & other ommon fators Lowest order PQCD preditions known, up to hoie of the mass sale at whih to evaluate α S 1 st order α S orretions to these ratios are also known Most are large (>~20%) Some are unphysial Fodder for postditions! J/ψ _ η, χ 0,2 _ J/ψ, ψ(2s) _ J/ψ, ψ(2s) _ γ γ γ γ γ g g g g B. Heltsley QWG Deays 22

23 Charmonium Annihilation Γ Ratios System η J/ψ J/ψ J/ψ J/ψ, ψ(2s) χ 0 χ 2 χ 0,2 γγ Ratio Lowest order L.O. Value Msd by CLEO γγ / gg (8 / 9) (α( / α S ) x 10-4 <2.6 x 10-4 (90%CL) γγγ / e + e - [64(π 2-9) / (243π)] α 5.3 x 10-4 (2.0±0.7) 0.7) x 10-4 γγγ / γgg (8 / 27) (α( / α S ) x 10-4 (1.3±0.4) x 10-4 γγγ / ggg (128 / 135) (α( / α S ) x 10-5 (1.8±0.4) x 10-5 γgg / ggg (16 / 5 ) (α( / α S ) ± ± γγ / gg ( 8 / 9 ) (α( / α S ) x 10-4 (2.3±0.4) x 10-4 γγ / gg ( 8 / 9 ) (α( / α S ) x 10-4 (4.3±0.6) x 10-4 γγ 2 / γγ 0 4 / ± Kwong, et al., PRD 37, 3210 (1988) Using α S =0.3 B. Heltsley QWG Deays 23

24 χj γ (ρ 0, ω, ϕ) B. Heltsley QWG Deays 24

25 χj γ (ρ0, ω, ϕ) Glue-rih system reoils against γ Clean experimental signatures ULs for B[χ 0,2 γ (ρ 0, ω, ϕ)] Observe B[χ 1 γ (ρ 0, ω)] )]~10-4 Fators of ~(15,50) higher than predition of Gao, Zhang, & Chao, CPL 23, 2376 (2006) χ 1 γ ρ 0 has ~full long. polarization Like f 1 (1285) γρ 0 [VES, χ 1 γ ρ 0 Longitudinal [VES, ZPC66, 71 (1995) ] (2.43±0.19±0.22) x 10-4 γ ρ 0 (0.83±0.15±0.12) x 10-4 γ ω γ ϕ χ 1 γ ω Transverse PRL 101, (2008) B. Heltsley QWG Deays 25

26 η Properties η π + π - π 0 Signifiane: >6σ η π + π - e + e - Signifiane: >6σ CLEO has studied η properties Mass error improved by fator of 5 Limits on rare hadroni modes 1 st observation of η π + π - π 0, π + π - e + e - properties via J/ψ γ η PRL101, (2008) B. Heltsley QWG Deays 26

27 Summary & Conlusions CLEO has measured a large number of harmonium annihilation rates B(J/ψ γ γ γ) ) = (12 ± 3 ± 2) x 10-6 B(J/ψ γ η ) x B( η γ γ ) = ( ± 0.3 ) x 10 6 χ J : Γ 2 (γγ)) / Γ 0 (γγ)) = ± ± ± J/ψ γ gg : R γ = ± ± ± ψ(2s) γ gg: : R γ = ± ± χ J γ (ρ 0, ω, ϕ) ) rates measured χ 1 γ (ρ 0, ω) BRs exeed predition by fator of (15,50) CLEO has studied η properties Mass error improved by fator of 5 Limits on rare hadroni modes 1 st observation of η π + π - π 0, π + π - e + e - properties via J/ψ γ η B. Heltsley QWG Deays 27

28 Charmonium Deay Analyses in Progress η exlusive branhing frations h deays to light hadrons J/ψ γ + invisible J/ψ invisible J/ψ, ψ(2s) γ/π 0 pp J/ψ, ψ(2s) γ f J γ (ππ,, KK, ηη) ) [glueball[ searh] J/ψ ππ,, KK, pp J/ψ, ψ(2s) baryon-antibaryon antibaryon ψ(4160) γ χ (2P) searh B. Heltsley QWG Deays 28

29 Bakup Slides B. Heltsley QWG Deays 29

30 η Properties B. Heltsley QWG Deays 30

31 η Properties Some properties of η (958) are not so well known M(PDG08) = ± 0.24 MeV Best msmt 1974: : MMS ± 0.33 MeV Compare to η mass error of 24 kev: η is less preise by a fator of 10 Rare BRs: : many mode limits of order 1-5% 1 B(η π + π - π 0 ) < 5% Of interest beause B(η π + π - π 0 ) m u -m d (or not!) Preditions vary from 0.1%-3%. Rate sensitive to level of η-η -π 0 mixing, final state resattering B(η π + π - e + e - ) < 0.6%. Predited to be ~0.2%. η 2(π + π - ) π 0, η 3(π + π - ), η 2(π + π - ) eah has a B < 1% Turns out that we an produe many η mesons in ψ(2s) π + π - J/ψ,, J/ψ γ η : ~40K in CLEO- data. Use ommon deay modes for mass measurement & searh for some rare modes Exlusive reonstrution & onstrained fitting B. Heltsley QWG Deays 31

32 η Mass J/ψ vtx J/ψ mass ψ(2s) vtx π + π - γ ψ(2s) 4-Mom π + π - γ π + π - η (γγ) π + π - η (γγ) π + π - η (π + π - π 0 ) π + π - η (π + π - π 0 ) ~4K reonstruted deays Fator of 5 in mass preision PRL101, (2008) η π + π - π 0 ross hek Mass M(PDG) B. Heltsley QWG Deays 32

33 Systemati errors η Mass B. Heltsley QWG Deays 33

34 arxiv: Rare η Deays η π + π - π 0 Signifiane: >6σ η π + π - e + e - Signifiane: >6σ ππγ onv. bgd 1 st Obs. PDG (10-4 ) η invisible Improved/ 1 st Limits B. Heltsley QWG Deays 34

35 Results for J/ψ nγ B. Heltsley QWG Deays 35

36 Matrix element for J/ψ 3 γ Lowest order for ortho-positronium 3γ deay: Ore & Powell, Phys. Rev. 75, 1696 (1949). < M 2 > = (512/3) π 2 α 6 Σ [ ( 1 x i )/ ( x j x k ) ] 2 where x i = 2 E * i / M J/ψ, E i =.o.m. γ i energy, i j,, k Weight the phase spae events by this fator to sulpt the distributions Is a very gentle sulpting Makes ( 0.2 ± 0.1 )% relative differene in effiieny ompared to pure phase spae 3 i=1 B. Heltsley QWG Deays 36

37 Belle evidene for η γ γ B ± K ± γγ Belle PLB 662 (2008) 323 Sig. = 4.1σ B( η γ γ ) = ( ) 10 4 B. Heltsley QWG Deays 37

38 χj γ (ρ, ω, ϕ) χ J _ u,d,s _ u,d,s ρ, ω, φ _ u,d,s _ u,d,s _ χ J f 1 B. Heltsley QWG Deays 38 χ J

39 J/ψ γ gg Small bgd subtration from non-j/ψ photons Signal B. Heltsley QWG Deays 39