Klaus P. Jungmann, Kernfysisch Versneller Instituut, Groningen, NL

1. The Muon g-2 Experiment Klaus P. Jungmann, Kernfysisch Versneller Instituut, Groningen, NL on behalf of the muon g-2 collaboration Lepton Moments II, Cape Cod, June 2003 Standard Model Precision Experiment Fundamental Constants Related Experiments Interpretation Future Possibilities

4. TRImP u d s c b t e ne m nm t nt Some Questions Left Open by Standard Model • Masses of Fundamental Fermions (leptons, quarks) • Why 3 generations? • Origin of Parity Violation in Weak Interactions • (nature prefers lefthandedness) • Dominance of Matterover Antimatter in Universe • CP - Violation, Time Reversal Symmetry

5. TRImP Possibilities to Test New Models  Low Energies & Precision Measurements High Energies & direct observations

6. Gravitation Electro- Magnetism Magnetism Maxwell Glashow, Salam, Weinberg, t‘Hooft, Veltman ? Electricity Weak Electro-Weak Standard Model Strong Grand Unification not yet known? Standard ModelDevelopment

10. minor error in calculations

11. The new measurement of the muon magnetic anomaly • at the Brookhaven National Laboratory aims for • 0.35 ppm relative accuracy. • Why? • We have in the listing of fundamental physical constants: • electron magnetic anomaly • 1.159 652 186 9(41) 10 -3 (0.0035 ppm) • muon magnetic anomaly • 1.165 916 02(64) x 10-3(0.55 ppm) Sensitivity to heavier objects larger by (mm/me)2 40 000

12. The new measurement of the muon magnetic anomaly • at the Brookhaven National Laboratory aims for • 0.35 ppm relative accuracy. • Why? • We have in the listing of fundamental physical constants: • electron magnetic anomaly • 1.159 652 186 9(41) 10 -3 (0.0035 ppm) • muon magnetic anomaly • 1.165 916 02(64) x 10-3(0.55 ppm)

13. QED - Contributions: am(QED) = 116 584 705.6(2.9) * 10-11(Kinoshita 2000) Weak Interaction Corrections: m m m m m m Dam(weak) = 151(4) * 10-11(Kutho 1992, Degrassi 1998)

14. QED - Contributions: am(QED) = 116 584 705.6(2.9) * 10-11(Kinoshita 2000) Weak Interaction Corrections: m m m m m m Dam(weak) = 151(4) * 10-11(Kutho 1992, Degrassi 1998)

16. ! ! Hadronic Corrections for gm-2 Dam(hadr.,1st order) = 6951(75)*10-11 (Davier, 1998) Dam(hadr., higherorder) = -101(6) *10-11 (Krause, 1996) Dam(hadr., light on light) = -79(15) *10-11 (Hayakawa, 1998) Situation Spring 2001

17. Early “Shopping List”

24. The fixed probes 4 ppm Proton NMR

25. The NMR-Trolley 17 probes - Proton NMR in water Electronics inside the trolley

26. Trolley NMR Probes NMR Trolley Fixed NMR Probes Electrostatic Quadrupole Electrodes Trolley Rails Vacuum Vessel

28. 900 000 000 positrons with E > 2GeV in 1999

30. Systematic Uncertainties, Results Spin Precession • Pileup 0.13 ppm • AGS background 0.10 ppm • Lost muons 0.10 ppm • Timing Shifts 0.10 ppm • E field and vertical CBO 0.08 ppm • Binning and Fitting procedure 0.07 ppm • Coherent Betatron Oscillations 0.05 ppm • beam debunching 0.04 ppm • Gain Instability 0.02 ppm total systematic uncertainty dwa,sy = 0.25 ppm total statistical uncertainty dwa,st = 1.25 ppm Magnetic Field • wp,0 spherical probe 0.05 ppm • wp(R,ti) 17 trolley probes 0.22 ppm • wp(R,t) 150 fixed probes 0.15 ppm • wp(R) aging - • wp (RI) inflector fringe field 0.20 ppm • < wp> muon distribution 0.12 ppm total systematic uncertainty dwp=0.4 ppm wp/2p = 61 791 256 (25) Hz wa/2p = 229 072.8 (0.3) Hz

31. m g-2 hadronic contribution weak contribution New Physics QED QED h mm, a, gm mm m+e- DnHFS, n=1 m+e- Dn1S-2S QED mm mm a QED corrections weak contribution mm QED corrections

32. Theory: * need a for muon ! * hadronic and weak corrections *various experimental sources of a<better 100ppb>need constants at very moderate *a no concern for (g-2)maccuracy wa wammc Experiment: wp = am = mm wa emB - wp mp * wa and B (wp) measured in (g-2)m experiment <better 0.35 and 0.1 ppm> * c is a defined quantity <“infinite” accuracy> *mm (mm) is measured in muonium spectroscopy (hfs) <better 120 ppb> NEW 1999 *em is measured in muonium spectroscopy (1s -2s) <better 1.2 ppb> NEW 1999 *mp in water known >> probe shape dependence<< <better 26 ppb> *m3He to mp in water >> gas has no shape effect << <better 4.5 ppb> being improved

38. Muonium Hyperfine Structure Yale - Heidelberg - Los Alamos Solenoid Dnexp = 4 463 302 765(53) Hz ( 12 ppb) Dntheo = 4 463 302 649(520)(34)(<100) Hz(<120 ppb) mm /mp = 3.183 345 13(39) (120 ppb) mm/me = 206.768 273(24) (120 ppb) a-1= 137.036 010 8(5 2)( 39 ppb) Sm m+ e- Detector m+in MW-Resonator W. Liu et al. Phys. Rev. Lett. 82, 711 (1999)

39. Muonium Hyperfine Structure Yale - Heidelberg - Los Alamos Solenoid Dnexp = 4 463 302 765(53) Hz ( 12 ppb) Dntheo = 4 463 302 649(520)(34)(<100) Hz(<120 ppb) mm /mp = 3.183 345 13(39) (120 ppb) mm/me = 206.768 273(24) (120 ppb) a-1= 137.036 010 8(5 2)( 39 ppb) Sm m+ e- Detector m+in MW-Resonator W. Liu et al. Phys. Rev. Lett. 82, 711 (1999)

40. Muonium 1S-2S Experiment Heidelberg - Oxford - Rutherford - Sussex - Siberia - Yale m++ e-+ Ekin 0 -.25 Rm 2S 244 nm Energy exp Dn 1s-2s = 2455 528 941.0(9.1)(3.7) MHz Dn 1s-2s = 2455 528 935.4(1.4) MHz mm+= 206.768 38 (17) me qm+= [ -1 -1.1 (2.1) 10-9 ] qe- 244 nm theo -Rm 1S m+ Detection m+ Laser Mirror m+e- Target Diagnostics m+in V.Meyer et al., Phys.Rev.Lett. 84, 1136 (2000)

42. 2.6 s deviation

43. Possible Explanations for Dam • am(exp) and am(latest theory) differ by 42(16) *10-10 • The probability for agreement is < 1% • Statistical Fluctuation • Undiscovered Error in Experiment • (not recognized systematics) • Not yet complete standard theory calculation • (hadronic contribution) • New Physics • 4 times more data on tape & data for m- being taken

45. About 1 year’s data needed Courtesy of W. Kluge, Karlsruhe (Summer 2001)

46. ! ! Hadronic Corrections for gm-2 ??SIGN ?? Dam(hadr.,1st order) = 6951(75)*10-11 (Davier, 1998) Dam(hadr., higherorder) = -101(6) *10-11 (Krause, 1996) Dam(hadr., light on light) = -79(15) *10-11 (Hayakawa, 1998)

47. ~ Muon Magnetic Anomaly in Super Symmetric Models Z k ~ ~ m m m m k k g g • no constraints from dark matter • constraint through dark matter ~ ~ w w + + - - m m ~ n • At, m0 vary over • parameter space • m0 < 1TeV/c2 approximate rule : DamSUSY» 1.4 * 10-9 * [ (100 GeV/c2) /mg ]2* tan b ~ goal BNL 821: am to 0.4 * 10-9 after: U. Chattopadyay and P. Nath, 1995

49. 2.6 s deviation 1.6 s deviation after light by light correction

50. Note:Even if there will be a difference between muon g-2 and theory established and unquestioned, it does not carry a tag about the nature of the difference! We will need further experiments then to learn more! Such as: - searches for rare muon decays - search for a muon edm - ..............................