Muon Particle Physics Masaharu Aoki Osaka University
Overview Introduction Static Properties Muon g-2 Muon EDM Dynamic Properties Lepton Flavor Violations e (MEG), e conversion (MECO,PRISM) Michel parameters Muon Factory Summary
Introduction Muon has been historically important Generation Structure (Flavor Conservation) V-A Structure of Weak Interaction VEV of Higgs field: Muon has been theoretically simple Pure Dirac fermion Muon has been experimentally convenient Easy to produce: T p > ~300 MeV Easy to handle: = 2.2 s Is Muon still attractive? YES OF CAUSE
NuFact04 6th International Workshop on Neutrino Factories and Neutrino Superbeams 26th July, 2004 ~ 1st August, 2004 Osaka University Working Group 4: Muon Physics MEG, MECO, PRISM, TWIST, e + polarization meas., Lan, FAST, g-2, EDM, etc.
Muon g-2
g-2 magnetic moment for spin 1/2 a is not zero
Theory J. Miller@NuFact04
BNL-E821 Results J. Miller@NuFact04
NEW Physics in g-2 J. Miller@NuFact04
Muon EDM
Muon Electric Dipole Moment Violate T, P SM prediction d ~2 x 10-38 e.cm The current experimental bound d ~(3.7 3.4) x 10-19 e.cm Beyond SM LRS + SeeSaw + -mixing: d ~ x 10-23 e.cm
EDM & g-2
Lepton Flavor Violation
Lepton Flavor Violation L i =1 Obviously LF is Violated for neutrinos. LFV referes to LFV for charged leptons. e, 3e, - A e - A, A A K L e, K L 0 e, K + + e e e e 0 ~ ~ 0 L i =2 + e - - e + A e e A, - A e + A, - A + A L =0 L =2
Recent Limits Reaction 90% CL Upper Limit + e + 1.2 x 10-11 + e + e - e + 1.0 x 10-12 - Ti e - Ti 4.3 x 10-12 - Pb e - Pb 4.6 x 10-11 - Au e - Au 4.4~6.8 x 10-13 - Ti e + Ca 3.6 x 10-11 - e + + e - 8.3 x 10-11 e 2.7 x 10-6 1.1 x 10-6 e e e 2.9 x 10-6 1.9 x 10-6 K L e 4.7 x 10-12 K L 0 e 6.2 x 10-9 K + + e 2.8 x 10-11 D 0 e, e 8.1 x 10-6, 3.4 x 10-5 B e, K e 1.5 x 10-6, 8 x 10-7 e, e, 1.7 x 10-6, 9.8 x 10-6, 1.2 x 10-5 J/, e 2.0 x 10-6, 8.3 x 10-6 Muon provides most sensitive limits Large number of muons available at Meson Factories Relatively longer muon life time = 2.2 s K = 12 ns
Oscillation & Muon LFV Lepton Flavor is already VIOLATED at sector. contribution to muon LFV process GIM suppression Very small Muon LFV indicates a physics beyond the simple oscillation
SUSY with RH Majorana neutrino SUSY + See-Saw Solar neutrino MSW large angle -LFV provides a clue to understand the oscillation MEG Goal MECO Goal PRISM/PRIME Goal
SUSY-GUT Prediction Process ~ Curren t Limit SUSY-GUT level Future Exp. PRISM/PRIME Goal N e N 10-13 10-16 10-18 (1) e 10-11 10-14 10-13 (2) 10-6 10-9 10-8 (3) e e 2 0-1 ab 1 ab -1 (4) (1) PRISM (2) MEG (3) Super-B (4) LC
SUSY Mass Matrix -LFV -EDM ~ ~ g-2 ~ ~ SUSY Mass Matrix Physics important as CKM and MNS
Leptogenesis CPV in CKM is not enough to explain Baryon Asymmetry New sources of CPV beyond the SM Oscillation + CPV in lepton sector leptogenesis (Fukugida & Yanagida 86) AND if SUSY exists T-violation in muon LFV muon EDM Imaginary part slepton mass matrix
New Generation of -LFV Experiments MEG BR( + e + ) < 10-13 MECO BR( - N e - N) < 10-16 PRISM/PRIME BR( - N e - N) < 10-18
MEG @ PSI + e + ICEPP, KEK, Waseda U., INFN, PSI, Budker Inst. PSI- E5 Beam Line R : 0.2-0.3 x 10 8 /s Run: 2006- Running Time: 4 x 10 7 s S.E.S.: 4 x 10-14
Signal and Background e + + e = 180 E e = E = 52.8 MeV T e = T signal + e + e + background correlated accidental e e e ee ez ez + e + + +
Required Performances Accidental Background Limited FWHM Exp./Lab Year Ee/Ee (%) E /E (%) te (ns) e (mrad) Stop rate (s-1) Duty cyc.(%) BR (90% CL) SIN 1977 8.7 9.3 1.4-5 x 10 5 100 3.6 x 10-9 TRIUMF 1977 10 8.7 6.7-2 x 10 5 100 1 x 10-9 LANL 1979 8.8 8 1.9 37 2.4 x 10 5 6.4 1.7 x 10-10 Crystal Box 1986 8 8 1.3 87 4 x 10 5 (6..9) 4.9 x 10-11 MEGA 1999 1.2 4.5 1.6 17 2.5 x 10 8 (6..7) 1.2 x 10-11 MEG 2007 0.7 4.5 0.1 19 2.5 x 10 7 100 1 x 10-13 - Liquid Xenon calorimeter (scintillation) - DC beam @PSI
Detector Outline Surface muon beam: 2~3 x 10 7 /sec in a 150 m target Solenoid spectrometer & drift chambers for e + momentum Scintillation counters for e + timing Liquid Xenon calorimeter for detection (scintillation) - fast: 4 / 22 / 45 ns - high LY: ~ 0.8 * NaI - short X 0 : 2.77 cm Construction on going Data Taking: 2006 ~
MECO @ BNL-AGS Superconducting Detector Solenoid (2.0 T 1.0 T) Muon Stopping Target Straw Tracker Crystal Calorimeter Muon Beam Stop Collimators Superconducting Transport Solenoid (2.5 T 2.1 T) Superconducting Production Solenoid (5.0 T 2.5 T) - Al e - Al BNL-AGS, pulsed proton beam Run: 2009- S.E.S.: 2 x 10-17 (equivalent to 5 x 10-15 of e ) Boston U., BNL, UCI, U. Houston, UMA, INR, NYU, Osaka U., U. Pennsylvania, Syracuse U., CWM
- -e - Conversion Muonic atom (1s state) nuclear muon capture nucleus - muon decay in orbit Source of BG Neutrinoless muon nuclear capture Single mono-energetic e - : E e = (M -B ) MeV (~105 MeV) Rate is normalized to the kinematically similar weak capture process:
Models: - N e - N SUSY-GUT (photonic process) BR ~ 10-15 SUSY with R-parity Violation Leptquarks Heavy Z -MZ > (5-100) TeV for R e~10-16 J. Bernabeu et al., NPB 409 (1993)69-86 Compositeness Multi-Higgs Models Higgs-Mediated Doubly Charged Higgs Boson
Potential Backgrounds No Accidental Background Muon Decay in Orbit Muon Decay in Orbit E max = E e, dn/de e (E max -E e ) 5 E e =900 kev FWHM N bg = 0.25 for R e =2 10-17 Energy Loss in the muon stopping target For the better resolution: thinner muon stopping target Thinner muon stopping target: narrow E spread of muon Signal
- N e - N vs. e - N e - N e Sensitive to non-photonic process Require new beam line No accidental background. New muon beam will boost the experiment further more. B( e ) = 200 B( - N e - N) for photonic process Strong physics motivation for both Existing surface muon beam Rate-limited due to accidental background. Possibly different systematics, thus complementary each others. Both should be done to maximize discovery potential -narrow p spread - thiner target
PRISM/PRIME Phase-Rotated Intense Slow Muon source PRIsm Muon Electron conversion exp. Accelerator Technology High Intensity 10 11-10 12 / sec High Brightness Phase Rotation dp/p: 20% 2% energy energy phase phase not in scale High Purity BR( N e N) < 10-16 BR( N e N) < 10-18
PRISM-Phase-Rotator Development AWARDED Grant-in-Aid for Creative Scientific Research A Study of A Super Muon Beam for New initiative on Muon Physics Five-years termed JFY2003 ~ JFY2007 Prove Phase Rotation Ionization Cooling Schedule 2003 : RF-PS development Mag. design 2004 : RF test Mag. prototyping 2005 : Mag. construction Ring construction 2006 : Commissioning 2007 : Phase Rotation Test Cooling Test Proposing to Install at J-PARC 0 5 10 15 20 0 5 10 15 (m)
L =2 i
L =0 Muonium-Antimuonium Conversion + e - - e double charged Higgs boson ++ heavy Majorana : M R > 10 4 GeV T.E. Clark, S.T. Love, Mod. Phys. Lett. A 19(2004)297-306 neutral scaler N bileptonic gauge boson X ++ Current limit: P MM < 8.3 x 10-11 @ PSI Future Plan: no concrete plans yet pulsed, high intensity, high brightness + beam (after K.P. Jungmann, however he mentioned slightly lower intensity and energy than PRISM, I think it s OK.) PRISM
Lepton No. Violation Majorana nature of e e N - e + N Conversion MECO by-product: BR( - e + N ) ~ 10-17 Correponding Kaon Process: K + - + e + BNL-E865 result: BR(K + - + e + ) = 5.0 x 10-10 equivalents to BR( - e + N ) ~ 3 x 10-11 L.S. Littenberg and R. Shrock, PLB 491(2000)285-290 - + N Conversion J.H.Missimer et al. PRD50(1994)2067-2070 BNL-E865 result: BR(K + - + + ) = 3.0 x 10-9 No direct measurements yet. R-parity violating SUSY: 5 x 10-9 y (BR~10-24 ) Need radioactive target high intensity, high brightness - beam
Muon Factory J-PARC 1 MW 50 GeV PS g-2: 0.05 ppm PRISM μ- Ν e- Ν: 10-18 PRISM-II μ-edm: 10-24~10-26 e.cm Muon Beam Manipulation Neutrino Factory Muon-Muon Collider
Summary Muon has been playing an important role in particle physics. is still providing us very important clues to understand the nature: g-2 will be also important in future of the particle physics: g-2, EDM, LFV Muon Factory
End of Slide