Highlights from BESIII

Transcription

1 Highlights from BESIII Hai-Bo Li for BESIII Collaboration Institute of High Energy Physics Beijing, China XIV International Conference on Hadron Spectroscopy June 13 17, 211 Künstlerhaus, in München, Germany June 15, 211 Hai-Bo Li (IHEP) 1

2 Outline Status of BEPCII/BESIII Results from Charmonium data samples 21-11: First open charm runs Charm Physics: advantage near threshold Conclusion June 15, 211 Hai-Bo Li (IHEP) 2

3 BESIII physics using charm Charmonium physics: - Spectroscopy - transitions and decays Light hadron physics: - meson & baryon spectroscopy - glueball & hybrid -two-photon physics - e.m. form factors of nucleon Charm physics: - (semi)leptonic + hadronic decays - decay constant, form factors - CKM matrix: Vcd, Vcs - - bar mixing and CP violation - rare/forbidden decays Tau physics: - Tau decays near threshold - tau mass scan and many more. June 15, 211 Hai-Bo Li (IHEP) 3

4 BESIII final goal J/ψ 1 1 ψ(2s) ψ(377) Higher ψ s 1 7 In decays: η c (1S)-1 8 χ cj 1 8 h c 1 7 (ψ(2s) h c π ) 1 8 η/η samples Rare η/η decays Comprehensive study of charmonium decays charm and charmonium spectroscopy June 15, 211 Hai-Bo Li (IHEP) 4

5 Satellite view of BEPCII /BESIII LINAC South BESIII detector 24: start BEPCII construction 28: test run of BEPCII 29-now: BECPII/BESIII data taking June 15, 211 Hai-Bo Li (IHEP) 5

6 BEPCII storage rings Beam energy: GeV esign Luminosity: cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: No. of bunches: 93 Bunch length: 1.5 cm Total current:.91 A Circumference: 237m June 15, 211 Hai-Bo Li (IHEP) 6

7 June 15, 211 Hai-Bo Li (IHEP) 7

8 ata samples So far BESIII has collected : 29: 225 Million J/ψ 29: 16 Million ψ 21-11: 2.9 fb 1 ψ(377) (3.5 CLEO-c.818fb 1 ) - May 211:.5fb MeV (one month) for s and XYZ spectroscopy BESIII will also collect: more J/ψ, ψ, ψ(377) data at higher energies (for XYZ searches, R scan and s physics) June 15, 211 Hai-Bo Li (IHEP) 8

9 luminosity since startup Note that luminosity is lower at J/ψ, and machine is optimal near ψ(377) Integrated luminosity: Jan. 29 June about 4. fb different energies Note increase in slopes! 211: ψ(377) & ψ(44) for s 21: ψ(377) 29: ψ & J/ψ June 15, 211 Hai-Bo Li (IHEP) 9

10 Recent ψ(377) running Reference point: L = /cm 2 /s (maximum ) theoretically lumi: 43 pb -1 /day But, filling beam, HV ramp, lumi. decay and down time loss 4% Best week : 16.8 pb -1 Best day : 29 pb -1 Beam current: 7 ma 7mA Luminosity curve (decay curve) Peak luminosity /cm 2 /s Best day on April June 15, 211 Hai-Bo Li (IHEP) 1

11 BESIII Collaboration 11 6 groups from Germany Helmholtz Institute Mainz Johannes Gutenberg-University Mainz Turkey: Turkish accelerator center 29 >3 physicists 49 institutions from 1 countries June 15, 211 Hai-Bo Li (IHEP) 11

12 Released results of BESIII Charmonium Spectroscopy and Transitions Properties of the h c (PRL 14, 1322 (21)) ψ γγj/ψ (submitted soon ) Charmonium ecays 1 papers published χ cj π π, ηη (PR 81, 525 (21)) χ cj γρ, γω, γφ (PR83,1125(211)) χ cj ωω, φφ, ωφ (submitted to PRL) ψ γπ, γη, γη (PRL 15, (21)) χ cj 4π (PR 83, 126 (211) ) Observation of χ cj ppk + K (accepted by PR) Light Quark States a (98) f (98) mixing (PR 83, 323 (211) ) η ηπ + π matrix element (PR 83, 123 (211)) X(186) in J/ψ γ(pp) (Chinese Physics C 34, 4 (21)) X(1835) in J/ψ γ(η π + π ) (PRL 16, 722 (211)) X(187) in J/ψ ω(ηπ + π ) (submitted soon) More than 2 analyses are under internal review! June 15, 211 Hai-Bo Li (IHEP) 12

13 Property of h c (1p1) June 15, 211 Hai-Bo Li (IHEP) 13

14 Observation of h c in inclusive reaction June 15, 211 Hai-Bo Li (IHEP) 14

15 h c (1P1) in ψ π h c, h c γη c, η c X i (exclusive) ψ π h C, h C γη C, η C is reconstructed exclusively with 16 decay modes Black from PG21, blue from estimation of ψ γη C For detail see Quarkonia session: Liangliang Wang s talk on June 13 June 15, 211 Hai-Bo Li (IHEP) 15

16 π recoil mass in h c γη c, η c X i Sum ofπ recoil mass Simultaneous fit to π recoiling mass in 16M ψ sample (preliminary results): M(h c ) = ±.11 (stat) ±.15 (sys) MeV/c 2 Γ(h c ) =.7±.28 (stat) ±.25 (sys) MeV N = 832±35 χ 2 /d.o.f. = 32/46 Consistent with BESIII inclusive results PRL14,1322(21) CLEOc exlusive results M(h c )= ±.27±.14 MeV/c 2 N = 136±14 PRL11, 1823(28) June 15, 211 Hai-Bo Li (IHEP) 16

17 η C lineshape from ψ π h C, h C γη C Sum of 16 of η C decay modes Background subtracted The η C lineshape is not distorted in the h C γη C etail analysis of η c parameters is ongoing! Symmetric lineshape in γγ production Asymmetric lineshape in ψ decay June 15, 211 Hai-Bo Li (IHEP) 17

18 η C resonance parameters from ψ γη C BESIII preliminary BESIII preliminary KsKπ KKπ ππη BESIII preliminary BESIII preliminary BESIII preliminary KsK3π 2K2ππ 3(ππ) BESIII preliminary Simultaneous fit with r-bw by considering the interference between η c and non-η c decays, as well as the energy dependence of phase space: mass: ±.5 stat ±.6 sys MeV/c 2 width: 3.5±1. stat ±.9 sys MeV φ: 2.35±.5 stat ±.4 sys rad φ: relative phase between η c decay and non-resonant component under the signal region by assuming all non-η c is +, and an universal phase for different modes is used. June 15, 211 Hai-Bo Li (IHEP) 18

19 Comparison of the mass and width for η c The world average in PG21 was using earlier results BESIII results include both stat. and syst. errors, which is the most precision measurement, the interference between η c decay and non-resonance is important. For detail see Quarkonia session on June 13: Liangliang Wang June 15, 211 Hai-Bo Li (IHEP) 19

20 Observation of η c (2S) in ψ γη c (2S),η c (2S) K s Kπ BESIII preliminary With 16M ψ events: M(η c (2S)) = (3638.5±2.3±1.) MeV/c 2 N(η c (2S)) = 5.6±9.7 Statistical significance larger than 6.σ! Br(ψ γη c (2S) γkskπ) =(2.98±.57 stat ±.48 sys ) Br(η c (2S) KKπ)=(1.9±.4±1.1)% From BABAR(PR78,126) M1 transition Γ(η c (2S)) fixed to 12MeV (world average) CLEO-c: < Br(ψ γη c (2S)) =(4.7±.9 stat ±3. sys ) 1-4 PR81,522(21) Potential model: (.1 6.2) 1 4 PRL89,1622(22) For detail see Quarkonia session on June 13: Liangliang Wang June 15, 211 Hai-Bo Li (IHEP) 2

21 Measurement of J/ψ pp, nn With 2.2 million J/ψ at BESIII, with help of EMC, we can access neutron-anti-neutron final states June 15, 211 Hai-Bo Li (IHEP) 21

22 Preliminary results: J/ψ pp, nn Anti-neutron identifications: BESIII preliminary BESIII preliminary BESIII preliminary nn pnπ EMC energy deposit:.6<e(anti-neutron)<2. GeV Comparison for anti-neutron in J/ψ nn and pnπ Angle between n and recoiling direction of n Angle between n and recoiling direction of n Br(J/ψ pp) = (2.112±.4±.27) 1-3 PG: Br(J/ψ pp) = (2.17±.7) 1-3 Br(J/ψ nn) = (2.7±.1±.14) 1-3 PG: Br(J/ψ nn) = (2.2±.4) 1-3 Br(J/ψ pp) ~ Br(J/ψ nn) suggests a large angle (~9 ) between strong and EM amplitudes! June 15, 211 Hai-Bo Li (IHEP) 22

23 Preliminary results: J/ψ pp, nn Anti-neutron identifications: BESIII preliminary BESIII preliminary BESIII preliminary nn pnπ Angle between n and recoiling direction of n EMC energy deposit:.6<e(anti-neutron)<2. This technique tells GeV us that we Comparison for anti-neutron can measure in J/ψ nn neutron-antineutron and pnπ Angle between n and recoiling cross direction section between of n GeV by using scan data, which is important. Br(J/ψ pp) = (2.112±.4±.27) 1 See MAGGIORA, -3 Marco in Quarkonia session PG: Br(J/ψ pp) = (2.17±.7) 1-3 Br(J/ψ pp) ~ Br(J/ψ nn) on June 13 suggests a large angle (~9 ) Br(J/ψ nn) = (2.7±.1±.14) 1-3 between strong and EM PG: Br(J/ψ nn) = (2.2±.4) 1-3 amplitudes! June 15, 211 Hai-Bo Li (IHEP) 23

24 Evidence for ψ decays into γπ and γη PRL15, 26181(21) We are measuring BRs at 1-6 June 15, 211 Hai-Bo Li (IHEP) 24

25 PRL15, 26181(21) Some surprises Q. Zhao, PLB697(211)52 June 15, 211 Hai-Bo Li (IHEP) 25

26 η(145) in J/ψ γf (98)π,f (98) ππ Changed: f(98) π + π Neutral f(98) π π f 1 (1285) 4.8σ BESIII preliminary Charged f 1 (1285) 1.4σ BESIII preliminary Neutral Helicity analysis indicates that peak at 14MeV is from η(145) f (98)π not from f 1 (142): First observation of η(145) f (98)π (isospin violated decays) and J/ψ γf (98)π Preliminary results: June 15, 211 Hai-Bo Li (IHEP) 26

27 New results on η 3π in J/ψ γπππ BESIII preliminary BESIII preliminary J/ψ γπ + π π J/ψ γπ π π Preliminary results: PG21: ( ) 1 3 (29 CLEO-c) PG21: (1.68±.22) 1 3 (1984: GAM2) June 15, 211 Hai-Bo Li (IHEP) 27

28 Confirmation of X(1835) and two new structures PRL 95,2621(25) BESII BESII result(stat. sig. ~ 7.7 σ ) : M = ± 6.1( stat) ± 2.7( syst) MeV Γ= 67.7 ± 2.3(stat) ± 7.7(syst)MeV BESIII fit results: J/ψ γη π + π η ηπ+π η γρ M 2.2 ππη (GeV/c ) X(1835) consistent with +, but the others are not excluded June 15, 211 Hai-Bo Li (IHEP) 28 ) 2 BESIII: 225M J/ψ events, new structures! Events/(.2GeV/c Resonance M( MeV/c 2 ) Γ( MeV/c 2 ) Stat.Sig. X(1835) ± ± >2σ X(212) ± ± σ X(237) ± ± σ f1(151) 2 1 An amplitude analysis could help with interpretation for the additional new structures! PRL 16, 722(211) two news!

29 What s the nature of new structures? PR73,14516(26) Y.Chen et al It is the first time resonant structures are observed in the 2.3 GeV/c 2 region, it is interesting since: LQC predicts that the lowest lying pseudoscalar glueball: around 2.3 GeV/c 2. + : 256(35)(12) 2 ++ : 239(3)(12) For detail see Light meson session: Hongwei Liu s talk on June 17 J/ψ-->γππη' decay is a good channel for finding -+ glueballs. Nature of X(212)/X(237) pseudoscalar glueball? η/η excited states? PR82,7426,21 J.F. Liu, G.J. ing and M.L.Yan PR83:1147,211 (J.S. Yu, Z.-F. Sun, X. Liu, Q. zhao), and more June 15, 211 Hai-Bo Li (IHEP) 29

30 X(187) in J/ψ ωx, X a (98)π a (98) J/ψ ωηπ + π, a (98) reconstructed in ηπ ± f 1 (1285) η(145) X(187): 7.2σ M(ηπ + π ) M(ηπ ± ) BESIII preliminary BESIII preliminary M(a (98)π) M(ηπ + π ) non-a (98) Identification of X(187): + (?) It is X(1835)? Need PWA! BR(J/ψ ωx, X ) June 15, 211 Hai-Bo Li (IHEP) 3

31 Preliminary results on N* baryon in ψ ηpp decay alitz plot data alitz plot MC fit A full PWA analysis performed selected in 16 M ψ events Background clean! N(1535) N(1535) is 1/2 Mass: Width: GeV M(pη) M(pp) Br(ψ' ppη)=(6.6±.2±.6) 1 5 Br(ψ' N(1535)p) Br(N(1535) pη+c.c.) PG21: (6±1.2) 1 5 = June 15, 211 Hai-Bo Li (IHEP) 31 GeV/C 2

32 Running plan The luminosity of BEPCII is better than expected. ata taking for open charm: ψ(377): 2.9 fb -1 (21 and 211) 41 MeV :.5 fb -1 in May 211 for s physics and XYZ Year Running 212 J/ ψ: 1 billion / ψ(2s):.5 billion (approved) MeV: s decay + R scan (E > 4 GeV) 214 ψ(2s)/τ / R scan (E > 4 GeV) 215 ψ(377): 5-1 fb -1 (our final goal) Red: be approved by BESIII Collaboration June 15, 211 Hai-Bo Li (IHEP) 32

33 Prospect of charm physics at BESIII June 15, 211 Hai-Bo Li (IHEP) 33

34 Advantage of open charm at threshold e + e Colliders@threshold: CLEO-c, BESIII, Super-taucharm Good for charm flavor physics: Threshold production: clean Known initial energy and quantum numbers Both and bar fully reconstructed (double tag) Absolute measurements June 15, 211 Hai-Bo Li (IHEP) 34

35 Charm role in flavor physics Theoretical errors dominate width of bands precision QC calculations tested with precision charm data at threshold theory errors of a few % on B system decay constants & semileptonic form factors Charm decay measurements decay constants form factors V CKM clean extraction validate QC. over-constrain V CKM Inconsistency New Physics June 15, 211 Hai-Bo Li (IHEP) 35

36 Clean single tag at with 42pb 1 first clean single tagging sample: BESIII Preliminary Kπ BESIII Preliminary BESIII Preliminary + Kππ BESIII Preliminary M = E p 2 2 BC beam Resolution: 1.3 MeV for pure charged modes; 1.9 MeV for modes with one π. Kπππ Kππ June 15, 211 Hai-Bo Li (IHEP) 36

37 Prospects for Charm at BESIII Look for the size of the statistics/systematic/fsr errors for precision measurements at BESIII after CLEO-c. CLEO-c errors for / + physics with 818 pb BESIII (5fb -1 ) f + ( + μ + ν ): ±4.1% (stat.) ± 1.2% (sys.) ±2.% (stat.) f π () ( πlν): ±5.3% (stat.) ±.7%(sys.) ±2.3% (stat.) BR( Kπ): ±.9% (stat.) ± 1.8%(sys.) limited by sys. BR( + Kππ): ±1.1% (stat.) ± 2.%(sys.) limited by sys. CLEO-c errors for s physics with 6pb MeV f s (s + μ + ν,τν ): ±2.5% (stat.) ± 1.2% (sys.) ±.8% (stat.) BR(s + KKπ): ±4.2% (stat.) ± 2.9%(sys.) ±2.% (stat.) For s physics, BESIII are taking data at both 41 and 417 MeV: 41 MeV (clean single tag, lower cross section.3 nb) BESIII.5 fb MeV (dirty single tag, maximum cross section.9 nb) CLEO-c.6 fb -1 Significant gains will be made with increased luminosity at BESIII. June 15, 211 Hai-Bo Li (IHEP) 37

38 Coherence + e e ψ(377) mixing: R M = (x 2 +y 2 )/2 ~ 1 4 ψ e + e For coherent process: '' ψ The initial state C=-1 1 = ( ) 2 The coherent amplitude Cˆ Cˆ = = Strong phase can be accessed, will be helpful for mixing measurements at super-b factories: Sensitivity on x will be improved by a factor of 3 Uncertainty of γ due to unknown relative phase on alitz decays Ks h + h - will be reduced to less than 1. CP violation in sector : 1 3 June 15, 211 Hai-Bo Li (IHEP) 38

39 Sensitivity of rare decays at BESIII Flavor Changing Neutral Current (c u l + l - ) μ + μ - SM <1-12 NP ~ 1-6 CF BR< X u l + l - SM <1-8 NP ~ 1-6 BR( + π + μ + μ - )< CLEO-c BR( + π + e + e - )< Lepton Flavor Violation NP ~ 1-6 BABAR BR( μ + e - ) < BABAR BR( + π + e + μ - ) < With 5-1fb BESIII will provide sensitivity. June 15, 211 Hai-Bo Li (IHEP) 39

40 Conclusion Huge data samples collected for Charmonium decays at BESIII The first observation of η c (2S) in ψ γη c (2S) decay Precision measurements of η C (1S) parameters in ψ γη c (1S) Confirmation of X(1835) in J/ψ γη π + π, Observation of two new structures X(212) and X(237) in J/ψ γππη decays Observation of new structure X(187) in J/ψ ωππη Charm near threshold undertake complementary studies of mixing and CPV, and unique test of QC techniques We expect rich physics results in the coming years from BESIII. June 15, 211 Hai-Bo Li (IHEP) 4

41 Thank you! After 36 years of discovery, Charm is still charming! Thanks! June 15, 211 Hai-Bo Li (IHEP) 41

42 Back up slides June 15, 211 Hai-Bo Li (IHEP) 42

43 Preliminary: relative phase between η c decays and non-η c background mode yield φ i (stat. ) χ 2 / dof K S Kπ ± KKπ ±.4.9 ππη ± K S K3π ±.2.7 2K2ππ ± π ± combined ±.5 - φ i values from each mode are consistent within 3σ: use a common phase in the simultaneous fit. June 15, 211 Hai-Bo Li (IHEP) 43

44 Vcs / Vcd from semileptonic decays Vcd will be improved at BESIII by a factor of 2. June 15, 211 Hai-Bo Li (IHEP) 44

45 + e bar quantum For a physical process producing such as e Z.Z. Xing, PR55, 196(1997) The correlated amplitude: e + e '' ψ The quantum number of is ψ '' For a correlated state C=-1: 1 J PC =1 ψ = ( ) Cˆ = 2 Cˆ = strong phase is necessary input for mixing and CKM measurements at B factories and LHCb June 15, 211 Hai-Bo Li (IHEP) 45

46 June 15, 211 Hai-Bo Li (IHEP) 46 Measure mixing at threshold )] )( ( [ )] )( ( [ )] )( ( [ )] )( ( [, ν ν ν ν π π π π = e K e K N e K e K N K K N K K N R M L H L H K K e e ) ( ) ( (377) m m π π ψ ± ± + At ψ(377) R M =(x 2 +y 2 )/2 can be measured using the ratios For 1 8 -pairs about 1 events will be detected. Sensitivity to R M is about Expected sensitivity to mixing parameters: 1 ab -1 at tau-charm factory = 1 ab -1 at Super B-factory Z.Z. Xing, PR55, 196(1997) + e e ) )( ( (377) m m π π ψ ± ± + K K e e Without mixing in, the following process is forbidden due to Boson-Einstein statistics : With mixing happened, it is allowed:

47 CPV in decay at BESIII irect CP violation in decays is expected to be small in SM. For CF and CS decays direct CP violation requires New Physics. Exception: ± K S,L π ± with A CP = For Singly Cabibbo Suppressed (SCS) decays SM CPV could reach 1-3. ACP = Γ( f Γ( f ) Γ( ) +Γ( At BESII, CP asymmetry can be tested with 1-3 sensitivity for many final states. f f ) ).S.u, EPJC5,579(27) Y. Grossman et al PR75, 368(27) Best limits: Belle: K + K -,π + π - A CP (K + K - )=(.43±.3±.11)% A CP (π + π - )=(.43±.52±.12)% BABAR: + K S π + A CP (K S π + )=(-.44±.13±.1)% CLEO-c : Ks π + π A CP (K S π + π )=(.3±.9±.3)% June 15, 211 Hai-Bo Li (IHEP) 47

48 CP violation near threshold CP violating asymmetries can be measured by searching for events with two CP odd or two CP even final states: π + π, K + K -, π π, Ksπ, for the decay of CP( f1 f2) = CP( f CP(ψ ) = + CP violation in mixing can be measured with: 1 ψ ) CP( f 2 ) ( 1) L f 1 f = A CP sensitivity : ΔA ~1-3 2 With 1 8 pairs in (K + e - ν)(k + e - ν) mode, q/p can be measured with (15-2)% accuracy. Current world averaged value is.86±.16. June 15, 211 Hai-Bo Li (IHEP) 48

49 HFAG: new charm mixing with CLEO-c Consider CLEO-c results. Asner Charm 21 June 15, 211 Hai-Bo Li (IHEP) 49

50 Brian Meadows ICHEP21 Project to 75ab 48 fb ab -1 Golden channels Min. χ 2 fits (blue contours) x y = (5.5 ± ) 1 3 = (8.3 ± 1.3) 1 3 Uncertainties shrink: but are limited by the irreducible model uncertainty (biggest effect on x ) Strong phase measurement from ψ(377) can greatly reduce this. x 3 = ( xxx ±.2) 1, y = ( xxx ±.12) 1 June 15, 211 Hai-Bo Li (IHEP) 5 3

51 The weak phase γ (φ 3 ) From A. Bondar CHARM21 u Interference between tree-level decays; theoretically clean Favored: V V * cb V * us cs V ub : suppressed s u b u K (*)- Common K (*)- s u B - final state B - c u f ( K ) ( K ) (*) A B A B = iδ iφ3 (*) Parameters: φ 3, (r B, δ) per mode Three methods for exploiting interference (choice of decay modes): Gronau, London, Wyler (GLW): Use CP eigenstates of (*) decay, e.g. K s π, π + π - Atwood, unietz, Soni (AS): Use doubly Cabibbo-suppressed decays, e.g. K + π - Giri, Grossman, Soffer, Zupan (GGSZ) / Belle: Use alitz plot analysis of 3-body decays, e.g. K s π + π - r June 15, 211 Hai-Bo Li (IHEP) 51 B e e c u b

52 B (K s h + h )K alitz plot for γ at B factory A powerful choice of common state f() in K s h + h BABAR: PRL 15, (21) Belle : PR 81, 1122 (21) ifferents between B and B + alitz plots allow γ extracted in unbinned fit. However, need to understand different amplitudes from and bar decay modes across alitz space, esp. variation in strong phase. Approach of B factories: construct alitz plot model of with flavor-tagged decays, estimated model uncertainty of 3-9, which is << statistical error. But super-b and LHC-b will start to be limited by this model uncertainty Highly desirable to have precision model independent approach! June 15, 211 Hai-Bo Li (IHEP) 52

53 δ From Jim Libby CHARM21 June 15, 211 Hai-Bo Li (IHEP) 53

54 CP-tagged alitz plots Clear difference between CP-even and CP-odd tagged alitz plots. BESIII will reduce this error to less than 1 June 15, 211 Hai-Bo Li (IHEP) 54