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Overview of BESIII Experiment

Overview of BESIII Experiment. Hai-Bo Li (Representing BESIII Collaboration) Institute of High Energy Physics Workshop on EIC Physics July 27-30, 2013, Weihai, Shandong University, China. Outline. Introduction BESIII data sets Selected results from BESIII

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Overview of BESIII Experiment

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  1. Overview of BESIII Experiment Hai-Bo Li (Representing BESIII Collaboration) Institute of High Energy Physics Workshop on EIC Physics July 27-30, 2013, Weihai, Shandong University, China

  2. Outline • Introduction • BESIII data sets • Selected results from BESIII • Hadron spectroscopy (XYZ, light hadron spec.) • Charmonium physics • Charm physics • Summary 2

  3. -charm: Main physics goals Hadron spectroscopy and test of QCD at low energy: Light meson and baryon Glueball: direct test of QCD at low energy Hybrid/exotics states/multiquark states/molecular states… Charmonium(-like) spectroscopy and decays / Charmed baryon decays Precise test of the Standard Model: R values, tau leptonic decays, CKM matrix, lepton universality test… Decay constants, form factors (in D meson decays) Neutral D mixing New physics searches at low energy ( tiny/forbidden in SM): Rare charmonium decays: weak decays, LFV, LNV, BNV … Rare charm and tau decays: FCNC, LFV, LNV, invisible decays Rare light meson decays: /// rare decays CP violation in tau and charm: tiny in SM CP violation in baryon /charmed baryon weak decays Exotic physics: Light dark matter candidates, Dark photon, light Higgs boson(a0), New interactions…

  4. Beijing Electron Positron Collider-II (BEPCII) LINAC BESIII detector 2004: started BEPCII/BESIII construction 2008: test run 2009 - now: BESIII physics run 4

  5. BEPCII storage rings Beam energy: 1.0-2.3 GeV Design Luminosity: 1×1033 cm-2s-1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10-4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A Circumference： 237m Achieved luminosity: 0.7×1032 cm-2s-1@3770MeV

  6. The BESIII Collaboration Europe (13) Germany: Univ. of Bochum, Univ. of Giessen, GSI Univ. of Johannes Gutenberg Helmholtz Ins. In Mainz Russia: JINR Dubna; BINP Novosibirsk Italy: Univ. of Torino，FrascatiLab, Ferrara Univ. Netherland：KVI/Univ. of Groningen Sweden: Uppsala Univ. Turkey: Turkey Accelerator Center US(6) Univ. of Hawaii Univ. of Washington Carnegie Mellon Univ. Univ. of Minnesota Univ. of Rochester Univ. of Indiana Korea (1) SeoulNat. Univ. Japan (1) Tokyo Univ. China(29) IHEP, CCAST, GUCAS, Shandong Univ., Univ. of Sci. and Tech. of China Zhejiang Univ., Huangshan Coll. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ. , Zhongshan Univ.,Nankai Univ., Beihang Univ. Shanxi Univ., Sichuan Univ., Univ. of South China Hunan Univ., Liaoning Univ. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Suzhou Univ., Hangzhou Normal Univ. Lanzhou Univ., Henan Sci. and Tech. Univ. Pakistan (2) Univ.of Punjab COMSAT CIIT ~350 members 52 institutions from 11 countries 7

  7. BESIII data taking status & plan

  8. BESIII collected 3.3/fb for XYZ study (2012-2013) 4230 4260 4360 4010 4210 4245 4090 3900 4220 3810 4390 4190 4310 4420 9

  9. Charmonium spectroscopy from Ryan Mitchell • Charmonium states below • open charm threshold are • all observed • Above open charm threshold: • many expected states not • observed • many unexpected charmoniumlike states observed X(3872) X(3915) X(4160) X(4350) Y(4008) Y(4140) Y(4260) Y(4360) Y(4660) Z(4430) Z(4250) Z(4050) Z(3900) XYZ(3940)

  10. Y(4260) e+e-ISR(J/) J/+ PRL95, 142001 273/fb PRL110, 252002 967/fb s(e+e- hadrons) s(e+e-  m+m-) PRD86, 051102 454/fb 4260 BESII

  11. Y(4360) and Y(4660) + e+e-ISR(’) PRL98, 212001 298/fb arXiv: 1211.6271, CHARM2012

  12. Select e+e +J/ at 4.26 GeV 525/pb @4.26 GeV BESIII: PRL110, 252001 (2013) 88233 J/ + 59528 J/ e+e

  13. Cross section of e+e +J/ Belle: 1304.0121 BaBar: PRD86, 051102 (2012) BESIII: (e+e- +-J/) = (62.91.93.7) pb Agree with BaBar & Belle! Best precision! BESIII: PRL110, 252001

  14. Observation of Zc(3900) at BESIII BESIII: PRL110, 252001 (2013) BESIII • M = 3899.03.64.9 MeV •  = 461020 MeV • 307  48 events Significance >8 The mass position is 24 MeV away from DD* threshold! A Partial wave analysis is on going!

  15. BELLE：e+e- +-J/ from ISR Belle: PRL 110, 252002(2013) CLEOc data at 4.17 GeV arXiv: 1304.3036 586/pb • M = 388551 MeV •  = 34124 MeV • 81  20 events • 6.1 • M = 3894.56.64.5 MeV •  = 632426 MeV • 159  49 events • >5.2

  16. Zc: charged charmoniumlike states • Find a clear signature for exotic state! • Decays to charmonium thus has a cc pair! • With electric charge thus has two more light quarks!  Nquark 4 ! • DD* molecule? Tetraquark state? Cusp? Threshold effect? • Do searches in πhc(1P), πψ(2S), πcJ, … • BESIII: e+e-  π+exotics, +exotics, …

  17. Observation of e+e- +-hc(1P) • 827 pb-1 at Ecm=4.26 GeV; 544 pb-1 at Ecm=4.36 GeV • hcghc, hc hadrons [16 exclusive decay modes] • pp, p+p-K+K-, p+p-pp, 2(K+K-), 2(p+p-), 3(p+p-) • 2(p+p-)K+K-, KS0K+p-+c.c., KS0K+p-p+p-+c.c., K+K-p0 • ppp0, K+K-h, p+p-h, p+p-p0p0, 2(p+p-)h, 2(p+p-p0) Ecm=4.26 GeV Ecm=4.36 GeV BESIII Preliminary 18 LP2013, C. Z. Yuan

  18. Observation of e+e +hc(1P) Ecm=4.26 GeV Ecm=4.36 GeV BESIII Preliminary N(hc)=41628 Lum=827/pb B= 41.02.87.4 pb N(hc)=35725 Lum=544/pb B= 52.33.79.2 pb 19

  19. Puzzle of “Y(4260)” Assuming the +hc(1P) is from Y(4260) decay: S(hc(1P)) = 0 S(J/) = 1 Spin-flip No spin-flip Process with spin-flip of heavy quark is not suppressed. Mechanism of +hc production is exotic! Study of the substructure is motivated !

  20. Ecm=4.26 GeV Ecm=4.36 GeV N= 5617 N= 6419 BESIII Preliminary Observation of Zc(4020) in e+e +hc(1P) Simultaneous fit to 4.26/4.36 GeV data and 16 c decay modes: 6.4  M(Zc(4020)) = 4021.81.02.5 MeV (Zc(4020)) = 5.73.41.1 MeV 21

  21. e+e (D*D*)++c.c. @4.26 GeV • 827 pb-1 data at Ecm=4.26 GeV • Tag a D+ and a bachelor , reconstruct one 0 to suppress the background. 22

  22. e+e  (D*D*)++c.c. @4.26 GeV Remove DD, DD*, D*D*, DsDs, … BESIII Preliminary 0 momentum 23

  23. BESIII Preliminary Observation of Zc(4025) in e+e(D*D*)++c.c. Fit to  recoil mass yields 40147 Zc(4025) events. >10 M(Zc(4025)) = 4026.32.63.7 MeV; (Zc(4025)) = 24.85.77.7 MeV 24

  24. Zc(4020)=Zc(4025)? High stat. data are needed! • M(4020) = 4021.81.02.5 MeV • M(4025) = 4026.32.63.7 MeV • (4020) = 5.73.41.1 MeV • (4025) = 24.85.77.7 MeV Close to D*D* threshold=4017 MeV Mass consistent with each other but width ~2 difference Interference with other amplitudes may change the results Coupling toD*D* is much larger than to hc if they are the same state Will fit with Flatte formula BESIII preliminary The Zc’ is found!

  25. What next at BESIII? • Precise resonant parameters • Spin-parity • More decay modes [, c, open charm,…] • Production mechanisms, production rates • Test various theoretical models • Neutral partners of Zc and Zc • Excited Zc, Zc states? ZcsKJ/ states? • Other XYZ states? • …

  26. X(3872) at BESIII

  27. Observation of e+e X(3872)+J/ Ecm=4.01 GeV Ecm=4.23 GeV BESIII Preliminary Ecm=4.26 GeV Ecm=4.36 GeV Clear ISR ’ signal for data validation X(3872) signal at around 4.23-4.26 GeV 28

  28. Sum of all energy points BESIII Preliminary Observation of e+eX(3872) ISR ’ signal is used for rate, mass, and mass resolution calibration. N(’)=1242 ; Mass=3685.960.05 MeV; M=1.84 0.06 MeV N(X(3872))=15.03.9 5.3 M(X(3872)) = 3872.10.80.3 MeV [PDG: 3871.68 0.17 MeV]

  29. BESIII Preliminary Observation of e+eX(3872) LP2013, C. Z. Yuan 30

  30. Light hadron spectroscopy-- from charmonium decays

  31. pp enhancement at threshold • Observed at BESII in 2003 • M=1859+3-10+5-25 MeV • Width < 30 MeV (90% CL) • Agree with spin zero expectation • Possibilities • Conventional meson? • pp bound state/ multiquark/ glueball/ … • Phys. Rev. Lett., 91, 022001

  32. Confirmed by CLEOc and BESIII • fit with one resonance as BES did: PRD 82, 092002 (2010) CPC 34, 421 (2010) M=1861 +6 -13+7-26 MeV/c2 G < 38 MeV/c2 (90% CL)

  33. PWA of J/pp @ BESIII BESIII: PRL 108, 112003 (2012) f0(2100) / f2(1910) fixed to PDG. Sig. of X(ppbar) >>30 Different FSI models  Model dependent uncertainty 34

  34. No significant narrow threshold enhancement observed here: PRD 73 (2006) 032001 EPJC 53 (2008) 15 @CLEOc PRD 82, 092002 (2010) PRL 108, 112003 (2012) Mpp (GeV) PRL 99 (2007) 011802

  35. X(1835) in + BESII: PRL 95,262001(2005) Statistical Significance ~ 6  Statistical Significance ~ 5.1  M=1833.7±6.1(stat)±2.7(syst)MeV =67.7±20.3(stat)±7.7(syst)MeV • Theoretical interpretation: • pp bound state, η excitation …. • Are X(pp) and X(1835) from the same source?

  36. X(1835) in J/ygp+p-h at BESIII • BESIII: PRL 108 (2011)112003 • Fit with four resonances (acceptance weighted BW gaussian) • Three background components: • Contribution from non-h’ events estimated by h’ mass sideband • Contribution from with re-weighting method • Contribution from “PS background” Red line: estimated contribution of ①+ ② Black line: total background

  37. The angular distribution of the X(1835) • BESIII: PRL 108 (2011)112003 • With bin-by-bin mass spectrum fit, we can obtain background-subtracted, acceptance-corrected angular distribution • Consistent with the expectation for a pseudoscalar, other assumptions are not excluded. 38

  38. Why are X(2120) and X(2370) interesting? PRD73,014516(2006) Y.Chen et al • First time in J/ radiative decays resonant structures are observed in the 2.4 GeV/c2 region. • it is interesting since: • LQCD predicts the lowest lying • 0-+ glueball: around 2.4 GeV/c2. • J/-->' decay is a good channel for finding 0-+ glueballs. • Nature of X(2120)/X(2370) • pseudoscalar glueball ? • / excited states? • …… PRD82,074026,2010 J.F. Liu, G.J. Ding and M.L.Yan PRD83:114007,2011 J.S. Yu, Z.-F. Sun, X. Liu, Q.zhao and more… 39

  39. X(18??) near the threshold position of proton-antiproton arXiv:1305.5333 Submitted to PRL X(1840): J/ 3( ) Observations at BESIII with 225M J/ decays: ★ J/ (3( )) X(1840) arXiV:1305.5333 ○ J/  () X(1870) PRL107, 182001 ▲ J/ (’) X(1835) PRL106, 072002 ■ J/ (ppbar) X(pp) PRL108,112003 ┼ J/ () X(1810) PRD 87, 032008 Are they the same particle? It is crucial to identify these Observations.

  40. PWA in J/ Phys. Rev. D. 87, 092009 (2013) • f0(1710) and f0(2100) are dominant scalars • f0(1500) exists (8.2σ) • f2’(1525) is the dominant tensor • f2(2340) exists (7.6) • No evidence for fJ(2220)

  41. Decay rate of pure glueball from LQCD Pure scalar-glueball rate in J/ radiative decays: Long-Cheng Gui et al. PRL 110 (2013) 021601 BR(J/ G(0++)) = 3.8(9)103 f0(1710)   Pure Tensor-glueball rate in J/ radiative decays: Yi-Bo Yang et al. arXiv: 1304.3807 Submitted to PRL BR(J/ G(2++)) = 1.1(2)102 Large decay rate is predicted! Need more experimental information!

  42. Study of J/f0(980)0, f0(980) BESIII: PRL 108 (2012) 182001 (1440) (1440) f1/ 3.7s f1/ 1.2s f0(980)+ f0(980)00 First observation of (1405)f0(980)0 (isospin violated decays) and J/f0(980)0

  43. Very narrow f0(980) – much narrower than PDG value! Possible explanation: J.J.Wu et al, PRL 108, 081803(2012) effect of Triangle Singularity!

  44. Large isospin breaking: (1440)f0(980)0 BESIII: PRL 108 (2012) 182001 In general, magnitude of isospin violation in strong decay should be less than 1% or at 0.1% level. For example: However:

  45. 3 in J/

  46. More results on / physics • Measurement of -> + e+e and ++. Phys.Rev. D87 (2013) 092011[arXiv:1303.7360 [hep-ex]]. • Search for  and + e+c.c. decays in J/ and . Phys.Rev. D87 (2013) 032006 • Search for  and  Invisible Decays in J/ and . Phys.Rev. D87 (2013) 012009 • Search for CP and P violating pseudoscalar decays into . Phys.Rev. D84 (2011) 032006 • Measurement of the Matrix Element for the Decay . Phys.Rev. D83 (2011) 012003. First observation +-+ First observation of 0 First observation of e+e, 0e+e- Study of ’ + … On going analyses:

  47. N* resonances in  decays 0ppbar Phys.Rev.Lett. 110 (2013) 022001  Two new baryonic excited states are observed ! J/ (’) decays offer an window to search for the missing baryon resonances. Many results are on going now at BESIII.

  48. Charmonium states’, hc(1P1), c(1S), c(2S) 49

  49. hc(1P1) state • Spin singlet P wave (S=0, L=1) • Potential model: • if non-zero P-wave spin-spin interaction: • DMhf(1P) = M(hc) - <m(1 3PJ)> ≠0 • where <m(1 3PJ)>= [(M(c0)+3M(c1)+5M(c2)]/9 • The hc(1P1) state was observed by CLEOc in 2005. Theoretical prediction: BF((2S)0hc) = (0.4-1.3)×10-4 BF(hcc) =48% (NRQCD) BF(hcc) =88% (PQCD) Kuang, PR D65 094024 (2002) BF(hcc) =38% Godfrey and Rosner, PR D66 014012(2002)

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