Hadronic Decay Studies in Charmonium with BESIII

Transcription

1 Hadronic Decay Studies in Charmonium with BESIII Johan Messchendorp, KVI/University of Groningen Workshop on Charmonium Decays, Orsay, 7th of March 13

2 BESIII Physics Programs Discovery and precision with Charmonium B(lookslikeDDforDorcharmphysics) E(lookslikeccforcharmoniumphysics) S (for light hadron Spectroscopy) T (for tau physics, looks like a Roman number III )

3 From 1974 till today: charmonium factories... ηc ( 1 S) ψ (1 D1) ψ ( 3 S1) July 8: first hadronic event March 9: physics data taking χc(1 3 P) χc1(1 3 P1) first hadronic event: July 8 J/ψ(1 3 S1) positron electron BEijing Spectrometer - III

4 - breaking all records 4.4 ηc(4 1 S) ηc(3 1 S) X(3915)? ηc ( 1 S) ψ(4 3 S1) Y(436) Y(46) ψ( 3 D1) ψ(3 3 S1) ψ (1 3 D1) ψ ( 3 S1) hc(3 1 P1) hc( 1 P1) χc(3 3 P) χc( 3 P) χc1(3 3 P1) X(387)? χc1( 3 P1) χc1(1 3 P1) χc(3 3 P) χc( 3 P) χc(1 3 P) ~.5 fb MeV ~.5 fb MeV ~.5 fb MeV NEW ~.9 fb -1 ~16 million (+more) χc(1 3 P) ηc(1 1 S) J/ψ(1 3 S1) ~5 million (+more) ~1-x previous generation charmonium factories

5 Charmonium physics potentials Resonance parameters details confinement potential - line shape studies - exotic resonances/xyz4. - missing charmonium states 4. ηc(3 1 S) Miscellaneous - e.m. formfactors - rare/forbidden decays - beyond SM physics X(3915)? ηc(4 1 S) ηc ( 1 S) ψ(4 3 S1) Y(436) Y(46) ψ( 3 D1) ψ(3 3 S1) ψ (1 3 D1) ψ ( 3 S1) hc(3 1 P1) hc( 1 P1) χc(3 3 P) χc( 3 P) χc(1 3 P) χc1(3 3 P1) X(387)? χc1( 3 P1) χc1(1 3 P1) χc(3 3 P) χc( 3 P) Open charm (D(s)) - fd decay constant - quark mixing matrix - Ds spectroscopy Tau physics - decays & mass Transitions & decays χc(1 3 P) - test validity pqcd - quark masses - strong coupling constant - constrain EFTs J/ψ(1 3 S1) Light hadron spectroscopy ηc(1 1 S) - light glueball&hybrid searches - baryon&meson spectroscopy

6 Hadronic Decay Studies with Charmonium This talk: 16M psi Physics aspects: Resonance parameters Rho-pi puzzle (1% rule) Perturbative QCD tests Hadronic loop effects Color Octet Mechanism Helicity Selection Rule Search for new states

7 P-wave hyperfine splitting V (r) = 4 s 3 r + kr + 3 s + 1 m c + 1 m c 9m c s r 3 r ~ S c ~ S c k r ~L S ~ 4 s 3 S ~ c ~r ~S c ~r r 3 r P-wave hyperfine splitting: / () Barnes, Godfrey, Swanson: PRD7, 546 (5) ~ Sc ~ S c!? M hf = m hc m c deviation from zero?

8 singlet P-wave hc PRL 14, 13 (1) isospin breaking! (E1)

9 PRL 14, 13 (1) (using 16M $(S) decays) (using 16M $(S) decays) (E1) The h c (1P) at BESIII %+ 1 %% 1 +% ! recoil mass (GeV/c ) ++ perfine splitting of 1P states is small (or ). singlet P-wave hc The h c (1P) at BESIII BESIII E1 photon tagged 3679±319 h c events 3679±319 $c(1 (18.6)) 3 P) h c events (18.6)) Inclusive Tag the photon to PRL measure 14, 13 (1) B(#(S)! $ Tag the E1 photon, hc) ' B(hc! %&c) yields: isospin Tag the = (4.58 photon ± to.4 measure ±.5) ' 1!4 breaking! (consistent B(#(S)! with $ h c ) CLEO) ' B(h c! %& c ) = (4.58 ±.4 ±.5) ' 1!4 (consistent with CLEO) Don t tag the photon to measure Inclusive analysis provides: Don t B(#(S) tag the! photon $ hc) to measure B(#(S) = (8.4! ± $ 1.3 hc) ± 1.) ' 1!4 (first = (8.4 measurement) ± 1.3 ± 1.) ' 1!4 (first measurement) Combining the two results: Combining branching fractions gives Combining branching fractions gives B(hc! %&c) = (54.3 ± 6.7 ± 5.)% B(hc! %&c) = (54.3 ± 6.7 ± 5.)% (first measurement) (first measurement) Natural width of hc: Also Also (hmeasure measure the the mass mass c ) =.73 ±.45 ±.8 MeV/c M(hc) = = ±.13 ±.13 ±.18 ±.18 MeV MeV (consistent with with CLEO) Hyperfine splitting: # Compare to: to: <M(& cj (1P))> (spin-weighted) = (consistent with CLEO-c) (first measurement) (first measurement) (first measurement) M hf =.1 ±.13 ±.18 MeV/c <M(& cj (1P))> (spin-weighted) (consistent = with zero)

10 singlet P-wave hc (E1) two years later exclusive channels

11 singlet P-wave hc ; exclusive decays of etac PRD 86, 99 (1)

12 B 1 (ψ(3686) π h c ) B (h c γη c ) B 3 (η c X i ) B singlet P-wave hc ; exclusive decays of etac B PRD 86, 99 (1) X i B 1 B B 3 ( 1 6 ) B 3 (%) B 3 in PDG (%) p p.65 ±.19 ±.1.15±.4±.±.1.141±.17 π + π π + π 7.51 ±.85 ± ±.19±.5±.17.86±.13 K + K K + K.94 ±.37 ±.14.±.8±.3±..134±.3 K + K π + π 4.16 ±.76 ±.59.95±.17±.13±.9.61±.1 p pπ + π.3 ±.65 ±.36.53±.15±.8±.5 <1. (at 9% C.L.) π + π π + π π + π 8.8 ± 1.57 ± 1.59.±.36±.36± ±.5 K + K π + π π π ± 1.71 ±.64.83±.39±.15±.8.71±.9 K + K π 4.54 ±.76 ± ±.17±.11±.1 1.±.1 p pπ 1.53 ±.49 ±.3.35±.11±.5±.3 KS K± π ± 1.5 ± 1.5.6±.9±.34±.5.4±. KS K± π π ± π 1.1 ±. ±.4.75±.51±.47±.7 π + π η 7. ± 1.47 ± ±.34±.6± ±1.8 K + K η.11 ± 1.1 ±.3.48±.3±.7±.5 <1.5 (at 9% C.L.) π + π π + π η ± 3.77 ± ±.86±.85±.4 π + π π π.31 ±. ± ±.5±.76±.45 π + π π + π π π ± 7.4 ± ±1.7±.9±1.66

13 singlet P-wave hc ; exclusive decays of etac (E1) Events / (1 MeV/c ) PRD 86, 99 (1) Sum of all 18 exclusive channel π recoil mass (GeV/c ) 16 exclusive channels Precision! M = ±.11 ±.14 MeV Γ =.7 ±.8 ±. MeV

14 P-wave hyperfine splitting Events / (1 MeV/c ) PRD 86, 99 (1) Sum of all 18 exclusive channel π recoil mass (GeV/c ) M hf hmð1 3 PÞi Mð1 1 P 1 Þ ¼ :1 :11ðstatÞ:15ðsystÞ MeV=c

15 exploiting isospin breaking breaking of isospin symmetry: u <-> d probe the ratio mu/md

16 exploiting isospin breaking breaking of isospin symmetry: u <-> d probe the ratio mu/md size of hadronic loops in charmonium Guo, Hanhart, Meissner PRL 13, 83 (9)! ð Þ

17 exploiting isospin breaking breaking of isospin symmetry: u <-> d probe the ratio mu/md CDF size of hadronic loops in charmonium understand nature of the X(387) state

18 exploiting isospin breaking breaking of isospin symmetry: u <-> d probe the ratio mu/md X(387)! J/ + size of hadronic loops in charmonium understand nature of the X(387) state Experiment CDF BaBar (B + ) BaBar (B ) D Belle LHCb World Average M(D )+M(D* ) PDG1 m=.1.35 MeV X mass ±.16 ±.19 MeV ±.6 ±.1 MeV ± 1.5 ±.4 MeV ± 3.1 ± MeV ±.7 ±.19 MeV ±.46 ±.1 MeV ±.17 MeV ±.3 MeV Γ < 1. MeV

19 exploiting isospin breaking breaking of isospin symmetry: u <-> d probe the ratio mu/md X(387)! J/ size of hadronic loops in charmonium P-wave understand nature of the X(387) state S-wave Isospin breaking enhanced for X(387)

20 exploiting isospin breaking 4.4 ηc(4 1 S) ηc(3 1 S) X(3915)? ηc ( 1 S) ψ(4 3 S1) Y(436) Y(46) ψ( 3 D1) ψ(3 3 S1) ψ (1 3 D1) ψ ( 3 S1) hc(3 1 P1) χc1(3 3 P1) χc(3 3 P) χc(3 3 P) transitions χc( 3 P) hc( 1 P1) X(387)? χc1( 3 P1) χc( 3 P) χc(1 3 P) χc1(1 3 P1) χc(1 3 P) B(ψ(41) π J/ψ) < Phys. Rev. D 86, 7111(R) (1) B( ' h c ) = (8.4 ± 1.3 ± 1.) 1-4 PRL 14, 13 (1) B( ' J/ )/B( ' J/ ) = (3.74 ±.6.6 ±.4) 1 - PRD 86, 98 (1) B(χ c, η c ) <? J/ψ(1 3 S1) ηc(1 1 S) In Progress valuable input to EFT approaches

21 charmonium ground state pp Mass (1S, S) c width C.L.=.14 C.L.<.1 13 Even on simplest parameters of the ground state there are consistency problems!

22 charmonium ground state CLEO-c, PRL 1, 1181 (9) 4.5M psi Breit-Wigner modified with E 3 dependence + detector response + damping function + (M1) light hadrons Precise resonance parameters require a thorough theoretical understanding of line shape!

23 charmonium ground state (M1) (E1) light hadrons

24 charmonium ground state (E1) Events / (1 MeV/c ) Events / (1 MeV/c ) (a) (b) M(hadrons) (GeV/c ) FIG. 3: (a) The hadronic mass spectrum in ψ(3686) π h c,h c γη c, η c X i summed over the 16 final states X i. The dots with error bars represent the hadronic mass spectrum in data. The solid line shows the total fit function and the dashed line is the background component of the fit. (b) The background-subtracted hadronic mass spectrum with the signal shape overlaid M(hadrons) (GeV/c ) Lineshape parameterization: E 3 BW(m) f d (E ) R i (m) E-dependence of E1 matrix element light hadrons Breit-Wigner resonance Damping factor (KEDR coll.) Detector response

25 charmonium ground state (E1) Events / (1 MeV/c ) Events / (1 MeV/c ) (a) (b) M(hadrons) (GeV/c ) FIG. 3: (a) The hadronic mass spectrum in ψ(3686) π h c,h c γη c, η c X i summed over the 16 final states X i. The dots with error bars represent the hadronic mass spectrum in data. The solid line shows the total fit function and the dashed line is the background component of the fit. (b) The background-subtracted hadronic mass spectrum with the signal shape overlaid M(hadrons) (GeV/c ) M( c ) = ± 1.16 ±.5 MeV/c ( c ) = 36.4 ± ± 1.7MeV/c light hadrons Interference with non-resonant background small...

26 charmonium ground state M1 transition to ground state: (M1) Significant larger statistics (no pi isospin-forbidden transition involved) hindered M1 transition small (large contribution of nonresonant background) light hadrons

27 PDF: charmonium ground state [ F (m) =σ ɛ(m) e iφ E 7/ S(m)+αN (m) ] + B(m) γ PRL18, (1) KsKπ" K + K π " π + π η " KsK3π " Kππ " 6π "

28 charmonium ground state Statistical significance of interference: 15 mode constructive destructive K S K + π.94 ± ±.6 K + K π.63 ± ±.19 ηπ + π.41 ± ±.9 K S K + π + π π.16 ± ±.7 K + K π + π π.73 ± ±.16 3(π + π ).8 ± ±.6 [rad] Bottom line: must take into account distorted line-shape and interferences with non-resonant decays

29 1 of 6 decay charmonium ground modes state PRL18, (1) vents / 1 MeV/c 14 data other ψ decays cont sig non-reso int 4 must take into account the distorted X line-shape π i (E 7 ) and interference with non-resonant decays M = ±.6 ±.6 MeV Γ = 3. ± 1. ± 1. MeV significant J discrepancies with older PC results (e.g. PRD 6, 71 ()) Events / 1 MeVc data other ψ decays π X i cont sig non-reso int

30 radial excitation of the g.s. Discovery of ηʹ c by Belle in B Kη cʹ ( KKπ) confirmed by BaBar, Cleo

31 radial excitation of the g.s. Discovery of ηʹ c by Belle in B Kη cʹ ( KKπ) (M1) confirmed by BaBar, Cleo o X o N Z & IO (b) CB, PRL48,7(198) LLI ~+It II II o I t 5 6 I 7 I 8 I 9 E~ (Mev). of a fit Disagreement of experiments on the mass and with early findings by Crystal Ball (3594). Only marginal consistency with most theoretical predictions. I I I I I

32 6 4 (M1) K K ) Events / (.5 GeV/c χc(1 3 P) hc(1 χc1(1 radial 1 P1). First observation of the excitation 3 P1) of the ψ(s) g.s. γηc(s) ± 3 data (K K π ) data (K K π ) S FIG. 1: The invariant-mass spectrum 3 1 fitting results PRD fitting 85, for K results 118 SK ± π (left (1) panel), K + K the three resonances and combined background sources as described i χ cj χ cj η c (S) 1 η c (S) ηc(1 1 S) 1 background 5. Search background for the hadronic B(η TABLE I: The absolute systematic uncertainties in the η c t c (S) mass 1(in MeV/c B(η ), width (in MeV) and the relative systematic error (in c χ ++ %) cj (1P) in BB, theproductbranchingfraction η c (1S)π + π expe B(ψ(3686) γη c (S)) B(η c (S) K Kπ), measurements. tion 1 arxiv: whe 1 E1-Dominated Transitions M1-Dominated Transitions Source Mass Width 5 BB BaB 3.7 m (GeV/c ) Background shape 1.3 K ± KS π m.6 K - π (GeV/c 9.9 ) In + K Damping function M1 FIG. 1: %+ The invariant-mass 1 %% 1 +% spectrum ++ for 1 ++ K SK ± ++ Fitting range proc π Charmonium (leftfirst panel), observation K + K and Mass π (right shift the panel), Role of M1 and of transition BESIII the simultaneous to.6. likelihood etac(s):.4 fit to mea the three resonances and combined background sources significance as described in the text. Tracking ~1 sigma Photon reconstruction itchell J/ψ(1 3 S1) χc(1 3 P) ± ) Events / (.5 GeV/c ) Events / (.5 GeV/c PRL 18, (1) PRL 19, 43 (1) data (K K π ) S fitting results m (GeV/c ) and helicity K ± KS analysis π for χc( ± η c (S) background ± ± ) Events / (.5 GeV/c 1 3. Study of χ cj ψ(s) π h c (1 1 h c (1P) γη c (1S) via η c (1S PRD 86, 99 (1) 4. Two-photon widths of th 3 1 1

33 PRL PRL 18, 18, (1) (1) First ofof η (S) Firstobservation observation η (S). First observation of the c. First observation of the c detector χc1(1 P1) χc(13p) Events ) h hcc(1 (11P P1) 1 χ (13P) χc c(13p) χ χ (1 (1 P P1)) radial excitation ofsignificance: theψ(s) g.s. PRL 19, 43 (1) Combined statistical ψ(s) γη γηcc(s) (S) PRL 19, 43 (1) >1σ 5 c1 c Combined statistical significance: >1σ 43 (1) PRL 19, m (GeV/c ) 43 (1) 19, ± PRL 3 K K π χc(13p) data MASS [GeV/c].... "#(3S1)!c#(1S) $c(13p) hc(11p1) K K J/ψ(1 J/ψ(1 S S )) JPC 1S) η c(1 η c(11s) J/"(1 S ) 3 1!c(11S) Mitchell Mitchell %+ 1%% $c1(13p1) $c(13p) PRD Γ = MeV(1) PRD±86, 86, 99 (1) 3 ± B(ψ(S) γηc(s)) = Two-photon widths of th 4. of th 15Two-photon widths 4 (6.8 1 ± 1.1 ± 4.5) 1 and helicity and helicity analysis analysis for for χ χc ( c( Events / 1MeV 13S1) ( ) 1 M "##(13D1) Events / 1MeV 3. ψ(s) 3. Study Study of of ψ(s) for π π hkcc#(1 (1 FIG. 1 (color online). The invariant-mass spectrum KSh BE M = γη ± c1.6 MeV likelihood fit to the three resonances and ±combined background so h via (1S cc(1p) h4 (1P) γη (1S) via η η (1S c(1s) cphoto E1c S ± χc(1 P) PRD PRD 85, 85, (1) (1) Incl Notes: 5 1) using Babar5. result: 5 4 Search for the hadronic tt 5. Search for the hadronic Using = (1.9 ±±.41.1)% ±+1.1)% 15 Using B(ηcB(η (S) K Kπ) ±.4 c (S) K Kπ) 3 = (1.9 χ (1P) 1 ηc(1s)π+π cj 3 Charmonium and the Role of BESIII χ (1P) η (1S)π π cj c (BABAR) 1 1 (BABAR) 5 ) consistent with B( Ψ(S) γη (S) ) = (6.8 ±± ) ± 4.5) 41 4 arxiv: c B( Ψ(S) γη (S) ) = (6.8 ± arxiv: E1-Dominated Transitions PC c J JPC (1)] 3.54 CLEO-c: < 7.6 [PRD 81, 5 CLEO-c: < [PRD 81, 5 (1)] 4 Potential models: (.1 6.) Potential models: (.1 6.) 1! recoil m [arxiv:99.81] 1+% [arxiv:99.81] 17 Charmonium 17 Charmonium and and the the Role Role of of BESIII BESIII JPC analysis

34 radial excitation of the g.s. ) ) PRD87, 55 (13) (M1)? Events / (.5 GeV/c data signal phase space QED background KsK3 KsK C M (GeV/c ) K σ (57 +/ 17 cnts) Events / (.5 GeV/c 3C K3 M KS K S (GeV/c ) M(η c ") = ±1.6± MeV/c Γ(η c ") = 9.9±4.8±.9 MeV Br(ψ' γη c " γk S Kπππ)=(7.3±.1±.7) 1-6

35 (M1) detector radial excitation of the g.s. Suppressed by helicity selection rule --> charmed meson loops (Liu, Zhao)? VV Events / 5 MeV/c Events / 5 MeV/c Events / 5 MeV/c (a) data η (S) c ψ /FSR cont π The upper limit on 1 35 at the 9% C.L., N N up γv V PDF(x)dx/ 3 (6 9) 1 3 PDF(x PDF. The left half of Table II 3C M ρ (GeV/c 5 ) ρ 8 from MC simulation, and product branching fraction B 6 Using B(ψ γη 4 1 c)=(4.7 ± corresponding upper limits on data the right half of Table II. In c (b) 3 1 K 4 15 K η (S) the error on B(ψ γη c c 1 ) - uncertainty to smear the PD ψ /FSR -4 tions [6] on branching fraction 1 cont calculated with Γ η c =1.4 ± 4 < π in Table II C M * * K K PRD84, 911(R) (11) (c) Events / 1MeV Events / 1MeV (GeV/c ) data Upper limits K, the PDF is taken to be in fitting the invariant mass setting the number of η c sign a very large number. For V η (9% c mass region C.L.) is taken as sig PDF is assumed to be a Poiss BE < E1 photo Incl (8 36) 1 3 In conclusion, no obvious decays into vector meson p φφ. The upper limits on th tion B(ψ γη c ) B(η c V fraction B(η c VV) are dete its are smaller than the lower predictions [6], although the η c φφ. < The BESIII Collaboration t and the computing center fo 1 work is supported in part by t Technology of China 3.53under Co 1 National Natural Science Fou under Contracts! No. recoil 165 m , No , N 1 ( 1) Academy of Sciences (CAS) 3C M φ φ (GeV/c ) cility Program; CAS under analysis arxiv: YW-N9, No. KJCX-YW-N of CAS; Istituto Nazionale

36 Charmonium Hadron Decay Studies with BESIII Quality data to study charmonium decays with world s best precision charmonium g.s. + radial excitation: new insights and discoveries! But thorough theory input required! P-wave singlet state (hc): mass and width measured, hadronic decay properties in progress... BESIII and the near future: more results at psi(s) mass to be expected new data at >4 GeV: discovery potential!

37 VV decays in P-wave charmonium (E1) Huge statistics due to large E1 transition rate VV Ideal testing ground for (perturbative) QCD calculations: c1! (,!!,! ) HSR: highly suppressed? long-distance effects? cj!! Doubly OZI suppressed To be observed?

38 VV decays in P-wave charmonium (E1) VV Events / 5 MeV / c Events / 5 MeV / c Events / 5 MeV / c (a) φφ χ c χ c1 χ c (b) φφ (c) ωω PRL17, 91 (11) Events / 1 MeV / c (d) ωφ M VV ( GeV/c ) BESIII Physics Programs B(lookslikeDDforDorcharmphysics) E(lookslikeccforcharmoniumphysics) S (for light hadron Spectroscopy) T (for tau physics, looks like a Roman number III )

39 VV decays in P-wave charmonium (E1) VV Mode N net ɛ (%) B( 1 4 ) χ c φφ 433 ± ±.4 ±.8 χ c1 φφ 54 ± ±.3 ±.4 χ c φφ 63 ± ±.4 ± 1.1 (K + K ) χ c φφ 179 ± ±.7 ± 1. χ c1 φφ 11 ± ±.5 ±.6 χ c φφ 19 ± ±.7 ± 1. K + K π + π π Combined: χ c φφ 8. ±.3 ±.8 χ c1 φφ 4.4 ±.3 ±.5 χ c φφ 1.7 ±.3 ± 1. χ c ωω 991 ± ±.3 ± 1.1 χ c1 ωω 597 ± ±.3 ±.7 χ c ωω 76 ± ±.3 ± 1.1 (π + π π ) χ c ωφ 76 ± ±.1 ±. χ c1 ωφ 15 ± ±.6 ±. χ c ωφ < <. K + K π + π π Observation Evidence Unique constraints for calculations!