1. B. Lee Roberts, BNL PAC 9 September 2004 - p. 1/29 Muon (g-2) to 0.20 ppm P969 B. Lee Roberts Representing the new g-2 collaboration: Boston, BNL, BINP, Cornell, Illinois, James Madison, Kentucky, KVI-Groningen, LBL&UC-Berkeley, Minnesota, Yale roberts@bu.eduroberts@bu.edu http://physics.bu.edu/roberts.html

2. B. Lee Roberts, BNL PAC 9 September 2004 - p. 2/29 This is a new collaboration built on the foundation of E821 Core of our expertise from E821 remains New institutes have joined and we are actively recruiting additional collaborators Our precision storage ring remains the centerpiece of the experiment

3. B. Lee Roberts, BNL PAC 9 September 2004 - p. 3/29 Standard Model Value for (g-2) from virtual radiative processes

4. B. Lee Roberts, BNL PAC 9 September 2004 - p. 4/29 Ongoing worldwide effort to improve knowledge of … Lowest order hadronic contribution Hadronic light-by-light

5. B. Lee Roberts, BNL PAC 9 September 2004 - p. 5/29 1 st -order hadronic from e + e - annihilation and  decay

6. B. Lee Roberts, BNL PAC 9 September 2004 - p. 6/29 Update: August 2004 (ICHEP) Precise e + e -  and  data are incompatible... especially at energies above the  New KLOE data using radiative return support the CMD2 e + e - data Isospin correction issues for the  data remain unresolved

7. B. Lee Roberts, BNL PAC 9 September 2004 - p. 7/29 Comparison with CMD-2 in the Energy Range 0.37 < s p <0.93 GeV 2 (375.6  0.8 stat  4.9 syst+theo ) 10 -10 (378.6  2.7 stat  2.3 syst+theo ) 10 -10 KLOE CMD2 1.3 % Error 0.9 % Error a   = ( 388.7  0.8 stat  3.5 syst  3.5 theo ) 10 -10 2 p contribution to a m hadr KLOE has evaluated the Dispersions Integral for the 2-Pion-Channel in the Energy Range 0.35 < s p <0.95 GeV 2 At large values of s  (>m   ) KLOE is consistent with CMD and therefore They confirm the deviation from t -data!. Pion Formfactor CMD-2 KLOE 0.40.50.60.70.80.9 s  [GeV 2 ] 45 40 35 30 25 20 15 10 5 45 0 KLOE, CMD2 Data on R(s) Courtesy of G. Venanzone

8. B. Lee Roberts, BNL PAC 9 September 2004 - p. 8/29 A. Höcker at ICHEP04

9. B. Lee Roberts, BNL PAC 9 September 2004 - p. 9/29 a μ is sensitive to a wide range of new physics muon substructure anomalous couplings SUSY (with large tanβ ) many other things (extra dimensions, etc.)

10. B. Lee Roberts, BNL PAC 9 September 2004 - p. 10/29 Where we came from:

11. B. Lee Roberts, BNL PAC 9 September 2004 - p. 11/29 Today with e + e - based theory: All E821 results were obtained with a “blind” analysis.

12. B. Lee Roberts, BNL PAC 9 September 2004 - p. 12/29 Discrepancy with e + e - based theory What might this mean? New physics or a fluctuation? –Consider a SUSY example

13. B. Lee Roberts, BNL PAC 9 September 2004 - p. 13/29 Courtesy K.Olive based on Ellis, Olive, Santoso, Spanos In CMSSM, a  can be combined with b s , cosmological relic density  h 2, and LEP Higgs searches to constrain  mass Allowed  band a  (exp) – a  (e+e- thy) Excluded by direct searches Excluded for neutral dark matter Preferred

14. B. Lee Roberts, BNL PAC 9 September 2004 - p. 14/29 Current Discrepancy Standard Model The CMSSM plot with error on  a  of 4.6 x 10 -10 (assuming better theory and a new BNL g-2 experiment)  a  =24(4.6) x 10 -10 (discrepancy at 6   a   0 (4.6) x 10 -10

15. B. Lee Roberts, BNL PAC 9 September 2004 - p. 15/29 Discrepancy with e + e - based theory What might this mean? New physics or a fluctuation? –Consider a SUSY example Either way, the muon (g-2) provides a wonderful test of the standard model

16. B. Lee Roberts, BNL PAC 9 September 2004 - p. 16/29 With a discrepancy like this… You’ve got to keep working –Either you confirm the discrepancy or –You show it’s not there… But you can’t ignore it! – The stakes are just too high. That’s why we’re here today.

17. B. Lee Roberts, BNL PAC 9 September 2004 - p. 17/29 The experimental concept remains the same:

18. B. Lee Roberts, BNL PAC 9 September 2004 - p. 18/29 And so does the ring

19. B. Lee Roberts, BNL PAC 9 September 2004 - p. 19/29 Strategy of the improved experiment More muons – E821 was statistics limited  stat = 0.46 ppm,  syst = 0.3 ppm –Backward-decay, higher-transmission beamline –New, open-end inflector –Upgrade detectors, electronics, DAQ Improve knowledge of magnetic field B –Improve calibration, field monitoring and measurement Reduce systematic errors on ω a –Improve the electronics and detectors –New parallel “integration” method of analysis

20. B. Lee Roberts, BNL PAC 9 September 2004 - p. 20/29 E821: Forward decay beam Pions @ 3.115 GeV/c Decay muons @ 3.094 GeV/c Pedestal vs. Time Near sideFar side

21. B. Lee Roberts, BNL PAC 9 September 2004 - p. 21/29 P969: Backward decay beam Expect for both sides Pions @ 5.32 GeV/c Decay muons @ 3.094 GeV/c No hadron-induced prompt flash Approximately the same muon flux is realized

22. B. Lee Roberts, BNL PAC 9 September 2004 - p. 22/29 Muon capture and transmission in decay section will double by doubling quads Lattice doubled E821 lattice

23. B. Lee Roberts, BNL PAC 9 September 2004 - p. 23/29 Improved transmission into the ring Inflector Inflector aperture Storage ring aperture E821 Closed EndP969 Proposed Open End

24. B. Lee Roberts, BNL PAC 9 September 2004 - p. 24/29 Systematic Error Evolution Field improvements will involve better trolley calibrations, better tracking of the field with time, temperature stability of room, improvements in the hardware Precession improvements will involve new scraping scheme, lower thresholds, more complete digitization periods, better energy calibration Systematic uncertainty (ppm)1998199920002001E969 Goal Magnetic field –  p 0.50.40.240.170.1 Anomalous precession –  a 0.80.3 0.210.1

25. B. Lee Roberts, BNL PAC 9 September 2004 - p. 25/29

26. B. Lee Roberts, BNL PAC 9 September 2004 - p. 26/29 E821: Precession Measurement

27. B. Lee Roberts, BNL PAC 9 September 2004 - p. 27/29 E969: Precession Measurement Expect 5 x more rate –Segment calorimeters –500 MHz waveform digitization –Greatly increased data volume for DAQ Introduce parallel “Q” method of data collection and analysis –Integrate energy flow vs. time T Method Q Method

28. B. Lee Roberts, BNL PAC 9 September 2004 - p. 28/29 Fast, dense and segmented W-SciFi calorimeters 20-fold segmentation 0.7 cm X 0 14%/Sqrt(E)

29. B. Lee Roberts, BNL PAC 9 September 2004 - p. 29/29 Schedule FY 2005 –R&D as funding permits FY 2006-2007 –Construction FY 2008 –Fall, pulse on demand, debugging –Spring, 3 week engineering run FY 2009 –2100 hours data collection (26 weeks @ 80 hr/wk)

30. B. Lee Roberts, BNL PAC 9 September 2004 - p. 30/29 Conclusions: With a 2.7 σ discrepancy … We can and must press ahead to the systematic limit of the technique The considerable investment to date at BNL can be further extended by modest upgrades We expect: 0.54 ppm → 0.2 ppm (projected) –In parallel, the theory effort continues and will improve to perhaps 0.3 ppm Muon (g-2) continues to address the most fundamental questions in our field

31. B. Lee Roberts, BNL PAC 9 September 2004 - p. 31/29

32. B. Lee Roberts, BNL PAC 9 September 2004 - p. 32/29 Systematic errors on ω a (ppm) σ systematic 1999 2000 2001E969 Pile-up0.13 0.080.07 AGS Background0.10 * Lost Muons0.10 0.090.04 Timing Shifts0.100.02 E-Field, Pitch0.080.03*0.05 Fitting/Binning0.070.06* CBO0.050.210.070.04 Beam Debunching0.04 * Gain Change0.020.13 0.03 total0.30.310.210.11 Σ* = 0.11

33. B. Lee Roberts, BNL PAC 9 September 2004 - p. 33/29 Goal for ω p systematic errors E969 (i ) (I) (II) (III) (iv) *higher multipoles, trolley voltage and temperature response, kicker eddy currents, and time- varying stray fields.

34. B. Lee Roberts, BNL PAC 9 September 2004 - p. 34/29 a(had) from hadronic decay? Must assume CVC, no second-class currents, make the appropriate isospin breaking corrections. decay has no isoscalar piece, while e + e - does Let’s look at the branching ratio and F π from the two data sets:

35. B. Lee Roberts, BNL PAC 9 September 2004 - p. 35/29 Tests of CVC (A. Höcker – ICHEP04)

36. B. Lee Roberts, BNL PAC 9 September 2004 - p. 36/29 Comparison with e + e - theory (from ICHEP04) (from F. Teubert’s summary talk.)

37. B. Lee Roberts, BNL PAC 9 September 2004 - p. 37/29 F. Teubert, ICHEP04 – E-W plenary summary talk

38. Field Uncertainties - History * higher multipoles, trolley voltage and temperature response, kicker eddy currents, and time-varying stray fields. (I) (II) (III) (IV) Source of Uncertainty 1998199920002001 Absolute Calibration0.05 Calibration of Trolley0.30.200.150.09 Trolley Measurements of B0 0.10.10 0.05 Interpolation with the fixed probes 0.30.150.100.07 Inflector fringe field0.20.20-- uncertainty from muon distribution 0.10.120.03 Other*0.150.10 Total 0.50.40.240.17

39. B. Lee Roberts, BNL PAC 9 September 2004 - p. 39/29 Field Shimming Source of UncertaintySource of Uncertainty 19981998 19991999 20002000 20012001 Absolute CalibrationAbsolute Calibration 0.050.05 0.050.05 0.050.05 0.050.05 Calibration of TrolleyCalibration of Trolley 0.30.3 0.200.20 0.150.15 0.090.09 Trolley Measurements of B0Trolley Measurements of B0 0.10.1 0.100.10 0.100.10 0.050.05 Interpolation with the fixed probesInterpolation with the fixed probes 0.30.3 0.150.15 0.100.10 0.070.07 Inflector fringe fieldInflector fringe field 0.20.2 0.200.20 -- uncertainty from muon distributionuncertainty from muon distribution 0.10.1 0.120.12 0.030.03 0.030.03 Other*Other* 0.150.15 0.100.10 0.100.10 TotalTotal 0.50.5 0.40.4 0.240.24 0.170.17 * higher multipoles, trolley voltage and temperature response, kicker eddy currents, and time-varying stray fields. * higher multipoles, trolley voltage and temperature response, kicker eddy currents, and time-varying stray fields. (I)(I) (II)(II) (III)(III) (IV)(IV) 2001