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Suggested plan of charmonia and QCD study scan at BESIII

Suggested plan of charmonia and QCD study scan at BESIII. Hu Haiming. October 12-16, 2011 Hangzhou. Outline. ☞ Physical Goals ☞ Suggested plan of data taking ☞ Estimations of beam time ☞ Tuning of generator LUARLW ☞ Improvement of ISR calculations ☞ …….

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Suggested plan of charmonia and QCD study scan at BESIII

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  1. Suggested plan of charmonia and QCD study scan at BESIII Hu Haiming October 12-16, 2011 Hangzhou

  2. Outline ☞Physical Goals ☞Suggestedplan of data taking ☞Estimations of beam time ☞ Tuning of generator LUARLW ☞ Improvement of ISR calculations ☞ ……

  3. Projects of BESIII physics Light hadron spectrumJ/ data Light charmonium (2S) data D physics (3770) data Heavy charmonia   Charm      (4040) (4190) (4415) X, Y, Z  ……  BESIII physics Mass Decay channels tau  R(s) fine scan (uds+c) QED & QCD (s), (g-2) multiplicity inclusive (correlation) exclusive form factors fragmentation functions Bose-Einstein correlation Uncharm  R&QCD 

  4. Projects of BESIII physics ☞Continuous states R value: 2.0  4.6 GeV meson and baryonform factors: 2.0  3.0 GeV fragmentation functions: 2.0  3.0 GeV …… ☞family parameters and decay ratio for J/, (2S), (3773), (4040), (4150), (4415), and new states X,Y,Z : 3.08  4.5 GeV ☞Hadronic MC generators LUARLW tuning parameters, signals, backgrounds, efficiencies

  5. Goal of accuracy with BESIII Academic significance: clear ! Precision/error: unknown ? Discussion& efforts …

  6. Data taking strategy Phase I Machine study (a few days) To optimize the plan for R scan, it is important to perform a machine study at energies of 4.2, 3.5, 2.5, 2.3 GeV before R scan, so that one knows the beam energy and the corresponding luminosities and time needed for the machine tuning. It could be arranged in the year 2012 and 2013? Using the data from the machine study, and the data collected at J/ , (2S), (3770) and (4010) et.al, one can perform prestudy (data analysis and generator pretuning) and establish the entire analysis chain.

  7. Data taking strategy Phase II Fine R scan between 3.85  4.4 GeV (90 days?) R scan from slightly above the open charm to the highest energy BEPCII can reaches (4.5 GeV ?). The total energy points to be scanned are about 80, and collect 10000 hadronic events at each energy point. A detailed scan with smaller steps in the energy region where X, Y, Z states were reported, and the suspected structures from the previous R measurements. Smaller steps (2 -5 MeV) are chosen for R scan around the peak positions of the resonances of (4040), (4160) and (4415), as well as the location where R values are suspiciously higher or lower than their surrounds, such as 3.9-4.0 GeV, around 4.06, 4.26 GeV.

  8. Data taking strategy Phase III R scan from 3.6  2 GeV (100 days) Collect large hadronic event samples from 3.6 GeV down to 2 GeV, with 15 energy points, each has 10000 hadronic events. Single beam and separated beam data at a few energy points covering the energy region to be scanned for R values are also needed for the estimation of the beam associated background. For the measurement of R value, proton form factor, the strong running couple constant, as well as tests the QCD by measuring the important inclusive and interested exclusive distributions.

  9. Estimation of beam time • Based on the following estimations or assumptions •  luminosity of BEPCII changes with beam energy •  ratio of normal running time of BEPCII and BESIII •  energy spread of BEPCII •  data taking efficiency •  hadronic event selection efficiency • hadronic cross section & ISR factor • required statistics • number of scanned energy points • beam time

  10. Formula used in beam time estimation Time estimation of data taking: The related quantities are estimated as following BEPCII luminosity:

  11. Formula used in beam time estimation Hadronic acceptance/efficiency: Efficiency of data taking: Effective cross section with energy spread: Factor of ISR correction:

  12. Requested e+e  pp data samples

  13. R measurement at BESII Phys.Lett.B677,(2009)239 BESII: Measured values Related errors (%) ? 2.53.0% BESIII:

  14. R Measurements at BESII

  15. Form factors of e+e  p p Production amplitude：　　　　 Hadronic current has two independent form factors: Electronic & magnetic form factors: ， Differential cross section : With large statistic data sample, GE and GM could be obtained by fitting angular distribution. But, with BESII data, and assume |GM=GE＝G| pQCD predicts BESII data for pp

  16. Ratiopuzzle of e+e  baryon pairs • FENICE data near threshold • QCD (quark model) prediction ? Puzzle • An intermediate coherent isovector state serving as an intermediary between e+e- and BB J. Ellis and M. Karliner hep-ph/0108259 QCD 10-24 sec r*,* • BESIII could collect data around 2.02.8 GeV , BB pairs f • QCD: s(e+e- D++ D++) : s(e+e- D+ D+): s(e+e- D0 D0) = 4:1:0 if at any particular energy, an I = 1 or I =0 resonance dominates, the above ratio will not be maintained! Wenbiao Yan USTC

  17. Measurement of sat BESII Solve equation Obtain coupling constant at every energies，and then evolve them to 5 GeV with Weighted average errors PDG2006

  18. Error of svs R precision The error of slarger than that of R 15 times。So, scan be determined directly based on R, and independent of any model, but not an “economical”way.

  19. Error of svs R precision Uncertainty rage of R within 1 Uncertainty rage of s within 1

  20. Charmonia The main properties in production and decay are described as the Breit-Wigner, and characterized by resonant parameters hadronic width electronic width phase angle nominal mass total width

  21. Known charmonia

  22. BES’s measurements of BW parameters ? J/ Why so many energy points were scanned Consider uncertainty of beam energy calibration, taking data at 23 energy points were reasonable. Phys. Lett. B355 (1995) Energy points : 23 Total luminosity : 82.28/nb Processes analyzed: Maximum error : 11%

  23. BES’s measurements of BW parameters (2S) Consider uncertainty of beam energy calibration, taking data at 24 energy points were reasonable. Events analyzed Phys. Lett. B550 (2002) Energy points : 24 Total luminosity : 1.149/pb Fit simultaneously Maximum error : 10%

  24. BESII’s measurements to BW parameters (3770) (4040) (4160) (4415) Data analysis: inclusive hadronic events no lepton pairs Phys. Rev. Lett. 97,121801 (2006) Phys. Lett. B652, 238(2007) Phys. Lett. B660, 315(2008) Energy points : 78

  25. BESII measurements quoted in PDG10

  26. BESII measurements quoted in PDG10

  27. PHIPSI2009

  28. (4160) or(4190)？ 在BES扫描数据拟合中发现，无论采用什么形式的连续本底以及强衰变宽度的能量相关性，只要考虑了相因子，过去所称的(4160)的质量都约为4190MeV；当丢掉相因子时，其质量拟合值都约为4160MeV。 两者相差约30MeV，远大于7MeV的拟合误差。这表明质量的移动是相因子效应。 在BES实验之前，已有不同的理论模型独立地预言了此共振态的质量约为4195MeV。

  29. Decay channels of higher charmonia

  30. Coupling channel model

  31. Potential models prediction Nonrelativistic potential model Relativizied potential model with QCD hep-ph/0505002 “Higher Charmonia” Experimental and theoretical spectrum of charmonium: Solid line: experiment Broken line: model

  32. Potential model predictions Phys. ReV. D32, 189 (1985)

  33. Potential model predictions Phys. ReV. D32, 189 (1985)

  34. Potential model predictions Phys. ReV. D32, 189 (1985)

  35. Potential model predictions Phys. ReV. D32, 189 (1985)

  36. Potential model predictions Phys. ReV. D32, 189 (1985)

  37. PHIPSI2009

  38. BESIImissed Y(4260) BESII曾以ΔEcm= 5 ~ 10 MeV的能量步长扫描了重粲共振态的结构, 但统计量较低,步长较大, 不能确认观察到的Ecm = 4.270 GeV处的突起是有物理意义的峰还是统计涨落. ! BABAR研究了初态辐射事例e+e- γ+ -, 并在有效能量处4.26 GeV观察到衰变末态+-的不变质量谱,因此发现了新粒子态 Y(4260). 理论对新共振态没有预言，是否还有可能存在还未发现的其它新结构和新粒子态？ BABAR-PUP-05/029 hep-ex/0506081

  39. DD DD* D*D* DDπ DD*π Λ+c Λc Sum of all exclusive contributions • Only small room for unaccounted contributions • Charm strange final states • Limited inclusive data above 4.5 GeV • Charm baryons final states Galina Pakhlova

  40. Comparison of theory and experiment T.Barnes’s paper Phys. Rev. D72, (2005)504026, hep-ph/0505002v3 Theory：non-relativistic potential model、Godfrey-Isgur model BESII value 25.6±6.3 ？ BESII value 88.9±12.4

  41. Comparison of theory and experiment ？ BESII value 78.8±16.1

  42. Comparison of theory and experiment ？ BESII value 80.4±24.7

  43. VEPP-4’s measurements of MJ/ and M(2S) hep-ex/0306050 J/ (2S) Energy points : 7 Scan : 3 run (E~0.9 MeV) Scan : 3+1 runs (E~0.6 0.45MeV) Total luminosity : 40+10/nb Total luminosity : 76/nb Highlight • Precise energy calibration • Precise energy spread calculation • …

  44. BEPCII energy measurement system Off-line data fitting: M =Mfit –MPDG =0.02± 0.05 MeV =M/2=0.010.03 MeV PDG2010: 3686.09 ± 0.04 MeV Accuracy of the beam energy measurement: de/e ~ 2×10-5 (36 keV). Two runs (2S) fitting Stability of the EMS

  45. Event selection in Ntot of J/ with BESIII Events types analyzed

  46. Event selection in Ntot of (2S) at BESIII Events types analyzed Error analysis

  47. Estimation of beam time 7points 25hr 12/pb 9points 33hr 16/pb 11points 39hr 18/pb 13points 48hr 22/pb J/ 15points 21points 17points 19points 23points 53hr 25/pb 60hr 28/pb 64hr 30/pb 68hr 32/pb 76hr 36/pb 7points 9points 11points 13points 14hr 13/pb 20hr 18/pb 23hr 22/pb 28hr 26/pb (2S) 15points 17points 21points 30hr 28/pb 34hr 32/pb 19points 39hr 37/pb 43hr 42/pb 23points 47hr 44/pb •  Assume 50,000 inclusive hadronic events are obtained at each energy point. • If the statistics are optimized and systematic error dominant is considered, • the beam time will be lesser than above values.

  48. Differentiation of BW J/ J/ (2S)

  49. Present test fitting Fitting without experimental data  Cook a meal without rice • Tricks: • Pseudo data: given by Breit-Wigner cross section with PDG parameters, • and consider energy spread, ISR correction and assumed background • as polynomial of level 1, set the error to be 3 % or 2%, and reasonable • beam unstability/fluctuation (b~0.1MeV). • Theoretical cross section: calculated by iterative Breit-Wigner form • with free parameters, consider energy spread, ISR correction, assumed • background as Chebychev polynomial of level 2. • Fitting tool: MINUIT. • Aim:①to learn how many scanned points are economic or efficient; • ②what accuracy level could achieved with BESIII; ③else more ?

  50. Fiting method Principle of least square with MINUIT Cross section to be fitted: High energy physics and nuclear physics 14, 585(1990) Free parameters Chebychev polynomial Pseudo experimental cross section: Gaussian, but >1.5% Fixed parameters Covariance matrix Correlation error matrix (typical value, assumption) Correlation coefficient:

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