B. Lee Roberts, BNL PAC 9 September 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

B. Lee Roberts, BNL PAC 9 September 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

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

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

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

B. Lee Roberts, BNL PAC 9 September 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

B. Lee Roberts, BNL PAC 9 September 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 ) (378.6  2.7 stat  2.3 syst+theo ) KLOE CMD2 1.3 % Error 0.9 % Error a   = (  0.8 stat  3.5 syst  3.5 theo ) 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 s  [GeV 2 ] KLOE, CMD2 Data on R(s) Courtesy of G. Venanzone

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

B. Lee Roberts, BNL PAC 9 September 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.)

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

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

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

B. Lee Roberts, BNL PAC 9 September 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

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

B. Lee Roberts, BNL PAC 9 September 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

B. Lee Roberts, BNL PAC 9 September 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.

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

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

B. Lee Roberts, BNL PAC 9 September 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

B. Lee Roberts, BNL PAC 9 September p. 20/29 E821: Forward decay beam GeV/c Decay GeV/c Pedestal vs. Time Near sideFar side

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

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

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

B. Lee Roberts, BNL PAC 9 September 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) E969 Goal Magnetic field –  p Anomalous precession –  a

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

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

B. Lee Roberts, BNL PAC 9 September 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

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

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

B. Lee Roberts, BNL PAC 9 September 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

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

B. Lee Roberts, BNL PAC 9 September p. 32/29 Systematic errors on ω a (ppm) σ systematic E969 Pile-up AGS Background0.10 * Lost Muons Timing Shifts E-Field, Pitch *0.05 Fitting/Binning * CBO Beam Debunching0.04 * Gain Change total Σ* = 0.11

B. Lee Roberts, BNL PAC 9 September 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.

B. Lee Roberts, BNL PAC 9 September 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:

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

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

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

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 Absolute Calibration0.05 Calibration of Trolley Trolley Measurements of B Interpolation with the fixed probes Inflector fringe field uncertainty from muon distribution Other* Total

B. Lee Roberts, BNL PAC 9 September p. 39/29 Field Shimming Source of UncertaintySource of Uncertainty Absolute CalibrationAbsolute Calibration Calibration of TrolleyCalibration of Trolley Trolley Measurements of B0Trolley Measurements of B Interpolation with the fixed probesInterpolation with the fixed probes Inflector fringe fieldInflector fringe field uncertainty from muon distributionuncertainty from muon distribution Other*Other* TotalTotal * 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