Lepton Flavor Violation - Experimental - Masaharu Aoki Osaka - PowerPoint PPT Presentation

Lepton Flavor Violation - Experimental - Masaharu Aoki Osaka University

Overview Introduction | Δ L i |=1 μ → e γ (MEG) μ → e conversion (MECO) PRISM | Δ L i |=2 Muon Factory Summary

Introduction

Obviously LF is Violated for neutrinos. LFV referes to LFV for charged leptons. Lepton Flavor Violation | Δ L i | =1 μ → e γ , μ → 3e, μ - A → e - A τ → μ γ , μ A → τ A’ K L → e μ , K L → π 0 e μ , K + → π + e μ ~ ~ e e → e μ χ 0 χ 0 | Δ L i | =2 μ + e - → μ - e + | Δ L|=0 A → e e A’, μ - A → e + A’, μ - A → μ + A’ | Δ L|=2

τ K = 12 ns Recent Limits Reaction 90% CL Upper Limit 1.2 x 10 -11 μ + → e + γ Muon provides most μ + → e + e - e + 1.0 x 10 -12 sensitive limits μ - Ti → e - Ti 4.3 x 10 -12 4.6 x 10 -11 μ - Pb → e - Pb μ - Au → e - Au 4.4~6.8 x 10 -13 Large number of muons μ - Ti → e + Ca 3.6 x 10 -11 available at Meson μ - e + → μ + e - 8.3 x 10 -11 Factories 2.7 x 10 -6 τ → e γ 1.1 x 10 -6 τ → μ γ Relatively longer muon life 2.9 x 10 -6 τ → e e e time 1.9 x 10 -6 τ → μ μ μ K L → μ e 4.7 x 10 -12 τ μ = 2.2 μ s K L → π 0 μ e 6.2 x 10 -9 K + → π + μ e 2.8 x 10 -11 D 0 → μ e, φ μ e 8.1 x 10 -6 , 3.4 x 10 -5 B → μ e, K μ e 1.5 x 10 -6 , 8 x 10 -7 Ζ → μ e, τ e, τμ 1.7 x 10 -6 , 9.8 x 10 -6 , 1.2 x 10 -5 2.0 x 10 -6 , 8.3 x 10 -6 J/ ψ → μ τ , e τ

Muon Lepton Flavor Violation - Experimental -

| Δ L i |=1

Lepton Flavor is already VIOLATED at ν sector. Muon LFV indicates a physics beyond the simple ν oscillation ν Oscillation & Muon LFV ν contribution to muon LFV process GIM suppression B ( µ → e γ ) = 2 m 2 � � 3 α m ν � 4 � 16 − 60 � � � � ν i � U µi U ∗ � � 10 − 2 eV ei M 2 32 π � W i Very small

to the ν oscillation μ-LFV provides a clue MEG Goal MECO Goal PRISM Goal SUSY with RH Majorana neutrino SUSY + See-Saw Solar neutrino MSW large angle

(4) LC PRISM Goal (3) Super-B (2) MEG (1) PRISM SUSY-GUT Prediction Current SUSY-GUT Future Process ~ Limit level Exp. 10 -13 10 -16 10 -18(1) μ N → e N 10 -11 10 -14 10 -13(2) μ → e γ 10 -6 10 -9 10 -8 (3) τ → μ γ e e → τ μ 2 χ 0 1 ab -1(4) - 1 ab

New Generation of µ -LFV Experiments MEG BR( μ + → e + γ ) < 10 -13 MECO BR( μ - N → e - N) < 10 -16 PRISM BR( μ - N → e - N) < 10 -18

MEG @ PSI μ + → e + γ ICEPP, KEK, Waseda U., INFN, PSI, Budker Inst. PSI- π E5 Beam Line R μ : 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 background signal accidental μ + → e + γ correlated μ → e ν ν μ → e γ ν ν μ → e γ ν ν e + γ ν μ + ee → γ γ e + γ eZ → eZ γ μ + θ e γ = 180° ν ν e + E e = E γ = 52.8 MeV μ + ν T e = T γ γ μ +

- DC beam @PSI FWHM Accidental Background Limited Required Performances BR acc ∝ R µ × ∆ E e × ∆ E 2 γ × ∆ θ 2 e γ × ∆ t e γ Δ Ee/Ee Δ E γ /E γ Δ te γ Δθ e γ Stop rate Duty BR Exp./Lab Year (%) (%) (ns) (mrad) (s-1) cyc.(%) (90% CL) 5 x 10 5 3.6 x 10 -9 SIN 1977 8.7 9.3 1.4 - 100 2 x 10 5 1 x 10 -9 TRIUMF 1977 10 8.7 6.7 - 100 2.4 x 10 5 1.7 x 10 -10 LANL 1979 8.8 8 1.9 37 6.4 4 x 10 5 4.9 x 10 -11 Crystal Box 1986 8 8 1.3 87 (6..9) 2.5 x 10 8 1.2 x 10 -11 MEGA 1999 1.2 4.5 1.6 17 (6..7) 2.5 x 10 7 1 x 10 -13 MEG 2007 0.7 4.5 0.1 19 100 - Liquid Xenon calorimeter (scintillation)

MECO @ BNL-AGS Muon Beam Crystal Stop Calorimeter Straw Superconducting Tracker Detector Solenoid (2.0 T – 1.0 T) Muon Stopping Target Collimators μ - Al → e - Al BNL-AGS, pulsed proton beam Superconducting Run: 2009- Transport Solenoid (2.5 T – 2.1 T) S.E.S.: 2 x 10 -17 (equivalent to 5 x 10 -15 of μ → e γ ) Boston U., BNL, UCI, U. Houston, UMA, Superconducting INR, NYU, Osaka U., U. Pennsylvania, Production Solenoid Syracuse U., CWM (5.0 T – 2.5 T)

Models: µ - N → e - N • SUSY with R-parity Violation • SUSY-GUT (photonic process) • Leptquarks – BR ~ 10-15 • Heavy Z’ - MZ’ > (5-100) TeV for R μ e~10-16 • J. Bernabeu et al., NPB 409 (1993)69-86 • Compositeness • Multi-Higgs Models • Higgs-Mediated • Doubly Charged Higgs Boson – Logarithmic enhancement in a loop diagram for µ -N → e-N, not for μ → e γ • M. Raidal and A. Santamaria, PLB 421 (1998) 250

Signal Muonic atom (1s state) nuclear muon capture µ − + ( A, Z ) → ν µ + ( A, Z − 1) nucleus μ - muon decay in orbit µ − → e − ν µ ν e Neutrinoless muon nuclear capture µ − ( A, Z ) → e − ( A, Z ) Single mono-energetic e - : E e = (M μ - B μ ) MeV (~105 MeV) Rate is normalized to the kinematically similar weak capture process: B ( µ − N → e − N ) = Γ ( µ − N → e − N ) Γ ( µ − N → ν µ N )

Potential Backgrounds No Accidental Background Muon Decay in Orbit Muon Decay in Orbit Signal E max = E e , dN/dE e ∝ (E max - E e ) 5 Δ E e =900 keV FWHM N bg = 0.25 for R μ e =2 × 10 -17 Radiative Pion Capture Limits allowed pion contamination in beam during detection time window. Radiative Muon Capture

Detector Outline Solenoid Pion Capture Crystal 1000 fold increase of muon rate Straw Calorimeter Tracker Pulsed Proton Beam Superconducting Detector Solenoid Eliminate prompt background. (2.0 T – 1.0 T) Good Detector Resolution and Large Acceptance Graded field around target Muon Stopping Target Long detector solenoid Superconducting Straw Tracker Transport Solenoid Optimized target thickness (2.5 T – 2.1 T) Superconducting Energy loss uncertainty Production Solenoid (5.0 T – 2.5 T) Muon stopping power

New muon beam will boost the experiment - narrow p μ spread - thiner target further more. µ - N → e - N vs. μ → e γ μ→ e γ μ -N → e-N • Sensitive to non-photonic process • B( μ→ e γ ) = 200 × B( μ -N → e-N) for photonic process Strong physics motivation for both • Existing surface muon beam • Require new beam line • Rate-limited due to accidental • No accidental background. background. Possibly different systematics, thus complementary each others. Both should be done to maximize discovery potential

Accelerator Technology PRISM Phase-Rotated Intense Slow Muon source !"(+,-)#(*'.%"/0) !#(*'4%3),"0 High Intensity 10%$'2,$3 !"#$%"&'!"()(* 10 11 - 10 12 μ ± / sec 4%3),"0'5(60*(#+ High Brightness A,(*'."%*73(") ."%*73(")'5(60*(#+ Phase Rotation dp/p:±20% → ±2% 8*90-)#(*'5&7)0$ 5 M energy energy ;<'4%=#)& <<>?'!@%70';()%)("';#*/ not in scale phase phase !@%70';()%)#(* High Purity :90-)#(*'5&7)0$ BR( μ N → e N) < 10-16 not in scale → BR( μ N → e N) < 10 -18

Install to J-PARC 電磁石電源 粒子検出器 取り出し光学系 入射光学系 高周波増幅器 高周波電源 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 (m) 0 5 10 15 15 20 0 Power Schedule 2003 : RF-PS development Injection Mag. design 5 RF 2004 : RF test Mag. prototyping 2005 : Mag. construction 10 Ring construction 2006 : Commissioning 2007 : Phase Rotation Test Extraction Cooling Test 15 15

| Δ L i |=2

Majorana nature of ν | Δ L|=2 Ν → e e N’ μ - Ν → e + N’ Conversion MECO by-product: BR( μ - Ν → e + N’) ~ 10 -17 Correponding Kaon Process: K + → π - μ + e + BNL-E865 result: BR(K + → π - μ + e + ) = 5.0 x 10 -10 equivalents to BR( μ - Ν → e + N’) ~ 3 x 10 -11 L.S. Littenberg and R. Shrock, PLB 491(2000)285-290 μ - Ν → μ + N’ Conversion J.H.Missimer et al. PRD50(1994)2067-2070 BNL-E865 result: BR(K + → π - μ + μ + ) = 3.0 x 10 -9 No direct measurements yet. R-parity violating SUSY: 5 x 10 -9 y (BR~10 -24 ) Need radioactive target PRISM high intensity, high brightness μ - beam

Muon Lepton Flavor Violation - Experimental -

Muon Lepton Flavor Violation and Other Muon Physics - Experimental -

slepton mass matrix Imaginary part Leptogenesis CPV in CKM is not enough to explain Baryon Asymmetry → New sources of CPV beyond the SM ν Oscillation + CPV in lepton sector → leptogenesis (Fukugida & Yanagida ‘86) AND if SUSY exists → T-violation in muon LFV muon EDM

SUSY Mass Matrix μ -LFV m 2 ∆ m 2 ∆ m 2   e ˜ ˜ e ˜ ˜ e ˜ ˜ e µ τ ∆ m 2 m 2 ∆ m 2   µ ˜ ˜ µ ˜ ˜ µ ˜ ˜ e µ τ ∆ m 2 ∆ m 2 m 2 τ ˜ ˜ τ ˜ ˜ τ ˜ ˜ e µ τ μ -EDM a μ (Exp)-a μ (e - e + ) = 2.7 σ o ff ~ ~ μ μ d μ < 10 -20 e.cm PRISM-II @ J-PARC g-2 PRISM for 500 MeV/ c muon ~ ~ μ μ d μ < 10 -24 e.cm (LoI to J-PARC)