-LFV and related topics M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Requests We were asked of focusing on the following items Physics motivation Technology aspects Cost estimates Manpower Interest in Italy … but I’ll discuss mainly the mLFV  x ~ M. Grassi – INFN Pisa Rome - November 7th , 2005

Examples of CLFV processes NeN’ ee  -LFV tlll t l t lp / lh / lh’ m N  t N’ X K system KL  e KL  p0e K±  p ± e Precise measurements -EDM g-2  decay parameters M. Grassi – INFN Pisa Rome - November 7th , 2005

Physics motivation they are experimentally accessible Charged Lepton Flavour Violation (CLFV) processes, like meg , meee , me conversion, and also teg , t m g , tlll , are negligibly small in the extended Standard Model (SM) with massive Dirac neutrinos (BR  10-50) Super-Symmetric extensions of the SM (SUSY-GUTs) with right handed neutrinos and see-saw mechanism may produce CLFV processes at significant rates CLFV decays are therefore a clean (no SM contaminated) indication of profound New Physics (mainly SUSY, but also on other exotic scenarios ) and they are experimentally accessible M. Grassi – INFN Pisa Rome - November 7th , 2005

Model independent indications Mag. Mom. Trans. Direct violat Effective interactions: Dependence upon arbitrary parameters  and F M. Grassi – INFN Pisa Rome - November 7th , 2005

Model independent indications The same effective interaction implies also a non zero mEDM and deviations for the muon gm-2 value with respect to the SM predictions M. Grassi – INFN Pisa Rome - November 7th , 2005

SUSY indications for meg LFV induced by finite slepton mixing through radiative corrections Experimental limit SUSY SU(5) predictions BR (meg)  10-14  10-13 SUSY SO(10) predictions BRSO(10)  100 BRSU(5) R. Barbieri et al., Phys. Lett. B338(1994) 212 R. Barbieri et al., Nucl. Phys. B445(1995) 215 small tan(b) excluded by LEP results M. Grassi – INFN Pisa Rome - November 7th , 2005

n-oscillation connection Additional contribution to slepton mixing from V21 (the matrix element responsible for solar neutrino deficit) Experimental limit tan(b)=30 tan(b)=1 J. Hisano, N. Nomura, Phys. Rev. D59 (1999)116010 M. Grassi – INFN Pisa Rome - November 7th , 2005

The muon trio gm-2 meg me conv mEDM In SUSY models the slepton mixing matrix links the three processes gm-2 meg me conv mEDM L. Roberts Y. Kuno M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 SU(5) LFV ratios 10-11 m<0 m>0 On large classes of SUSY-GUT BR(m-e conv)  10-2 BR(meg) BR(m3e)  10-2 BR(meg) BR(t mg)  10+5 BR(meg) m-e:Ti conv 10-20 meg J.Hisano et al., Phys.Lett. B391(1997)341 10-20 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 CLFV comparison BR(tmg) x 108 102 103 BR(meg) x 1012 10-2 Within the same, or among different unification models the predictions of CLFV processes have large variations J.Ellis et al., Eur.Phys.J. C14(2000)319 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Predictions ? Huge spread of SUSY prediction 10-12 – 10-19 In R-violating SUSY the dominant process are m3e and m-e conv Super Symmetry does not exist... Extra dimensions theories have parameters values with measurable BR Choice based on feasibility arguments M. Grassi – INFN Pisa Rome - November 7th , 2005

Experimental situation LFV searches Orders of magnitude improvement are required: experimental challenge! M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 m sector 3e e NeN’ -EDM g-2 ee dedicated beams dedicated experiments single purpose M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+e+e- background signal   eee accidental   e n n e+e- e+e- e+ + e+ e- correlated   e e e n n e+ + n e- e+ e+ + n Coplanarity Vertexing Ee = m Te+ = Te+ = Te- + n e+ e- M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+e+e- : SINDRUM I Present limit B(m3e ) < 1x10-12 U.Bellgardt et al. Nucl.Phys. B299(1988)1 No other experimental proposal This channel has only charged particles in the final state The experiment needs only a tracking system but Sustain the entire Michel decay rate Down to low momentum 4p coverage SINDRUM I parameters beam intensity 6x106 m+/s m+ momentum 25 MeV/c magnetic field 0.33T acceptance 24% momentum res. 10% FWHM vertex res.  2 mm2 FWHM timing res.  ns target length 220 mm target density 11 mg/cm2 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+e+e- : future SINDRUM: sensitivity  10-12 background  10-13 A new experiment should aim to a sensitivity: B  10-16 would require  109 m+/s but background  10-10 (6 order of magnitude !) Exercise: detector improvements for just a 104 factor momentum resolution 10% FWHM  1% FWHM bckg scales quadratically with momentum resolution co-planarity test ? vertex resolution 2 mm2  <1 mm2 target length 220 mm  ? target density 11 mg/cm2  ? timing resolution  ns   100 ps (accidental background increases quadratically with the muon stop rate) M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+e+e- : summary No other experimental proposal Six orders of magnitude of background reduction are required four orders of magnitude could be achieved, two more? This is not a relevant item M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 background signal   e g accidental   e n n   e g n n ee  g g eZ  eZ g correlated physical   e g n n e+ + g e+ + g n e+ + n qeg = 180° Ee = Eg = 52.8 MeV Te = Tg g M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+ : present Present limit B(e) < 1.2x10-11 by the MEGA Collab. M.L.Brooks et al. Phys.Rev.Lett. 83(1999)1521 Near to start data-taking experiment: MEG M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+ : MEG experimental method Easy signal selection with + at rest Detector outline Stopped beam of 3x107  /sec in a 150 mm target Liquid Xenon calorimeter for  detection (scintillation) fast: 4 / 22 / 45 ns high LY: ~ 0.8 * NaI short X0: 2.77 cm Solenoid spectrometer & drift chambers for e+ momentum Scintillation counters for e+ timing e+ + g Ee = Eg = 52.8 MeV qeg = 180° M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+ : MEG required performances The sensitivity is limited by the by the accidental background The  310-14 allows BR (meg)  10-13 but needs FWHM Exp./Lab Year DEe/Ee (%) DEg /Eg Dteg (ns) Dqeg (mrad) Stop rate (s-1) Duty cyc.(%) BR (90% CL) SIN 1977 8.7 9.3 1.4 - 5 x 105 100 3.6 x 10-9 TRIUMF 10 6.7 2 x 105 1 x 10-9 LANL 1979 8.8 8 1.9 37 2.4 x 105 6.4 1.7 x 10-10 Crystal Box 1986 1.3 87 4 x 105 (6..9) 4.9 x 10-11 MEGA 1999 1.2 4.5 1.6 17 2.5 x 108 (6..7) 1.2 x 10-11 MEG 2006 0.8 4 0.15 19 2.5 x 107 1 x 10-13 M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+ : correlated background The correlated background is smaller than the accidental one The correlated background has a complicate dependence on the photon (y) and positron (x) energy resolutions. Its rate depends linearly on the R The BR is 3x10-15 M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+ : MEG sensitivity summary Cuts at 1,4FWHM Detector parameters Signal  410-14 Single Event Sensitivity  310-14  310-15 Backgrounds Upper Limit at 90% CL BR (meg)  110-13 Discovery 4 events (P = 210-3) correspond BR = 210-13 M. Grassi – INFN Pisa Rome - November 7th , 2005

+e+ : MEG time profile 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Planning R & D Assembly Data Taking now LoI Proposal Revised document http://meg.psi.ch http://meg.pi.infn.it http://meg.icepp.s.u-tokyo.ac.jp More details at M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+ summary The PSI E5 can deliver up to 3x108 +/s The MEG sensitivity is accidental background limited With better detector resolutions a BR of 10-14 would be possible No need, at least for the next 10 years, for a more intense beam M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 +e+ comments Total MEG cost: 7.5 M€ At the limit of present-day technology Detector completion in spring 2006 Engineering runs 2006 Full statistic 3 years A few months data taking for a factor 10 improvement (2007) Italian collaboration: 4 groups fully committed (adding up ~20 fte) Near future: Detector improvement Polarized m beam (in case of signal !) M. Grassi – INFN Pisa Rome - November 7th , 2005

-e- conversion background Signal Ee = mm -EB -ER  (A,Z)  e (A,Z) coherent LFV decay  (A,Z)  e (A,Z) RPC (radiative pion capture)  (A,Z)   (A,Z-1) e- - g (A,Z) - g (A,Z) MIO (muon decay in orbit)  (A,Z)  e n n (A,Z) Ee = mm -EB -ER e- - n (A,Z) M. Grassi – INFN Pisa Rome - November 7th , 2005

-e- generalities 1 particle in the final state: no accidental Background chance for pushing down the limit on BR Event selection based on e- momentum only m lifetime ~.9 ms on Al or .35 ms on Ti Key element: beam quality ! Short (dt ~ 10ns) and intense (~ 1013 m/s) pulses of low momentum m (~ 68 MeV/c) Long beam off intervals ( Dt ~ 1 ms ) Extremely low p contamination (10-9 proton extinction or FFAG) Narrow momentum spread (<2 % with FFAG) M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 -e- : sensitivity R.Kitano et al Phys.Rev.D66(2002)096002 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 -e- conv. present Present limit B(me:Au ) < 8x10-13 by the SINDRUM II A. Van der Schaaf, NOON03 New approved experiment: MECO B(me) < 10-16 (2008 ? ) New project LOI to J-PARC: PRISM/PRIME B(me) < 10-18 (>2010 ? ) cancelled M. Grassi – INFN Pisa Rome - November 7th , 2005

-e- : SINDRUM II result SINDRUM II parameters beam intensity 3x107 m-/s m- momentum 53 MeV/c magnetic field 0.33T acceptance 7% momentum res. 2% FWHM S.E.S 3.3x10-13 B(me:Au ) 8x10-13 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 -e- : PRISM beam Phase Rotated Intense Slow Muon source To be operated at J-PARC (Japan) or elsewhere !!! (if J-PARC …) Based on a FFAG ring FFAG funded by Osaka Univ. Ready end 2007 M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 -e- : PRISM beam Muon momentum spread reduction by phase rotation down to 2  3 % FWHM Intensity  1012 m/s (no pions); Muon momentum 68 MeV/c. The small energy spread allows very thin targets (<100 mm) If a momentum resolution  350 keV FWHM is reached, the experiment could be sensitive to m  e conversion with SES ~ 6x10-19 BR ~ 10-18 Phase rotation concept M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 -e- : PRIME detector Only a LOI has been presented at J-PARC The detector is in form of conceptual design The Collaboration seed is formed by Jap and US researchers Cost ??? Timescale ??? The physics channel is a very challenging but really interesting M. Grassi – INFN Pisa Rome - November 7th , 2005

-e- and +e+ as probes of New Physics me conv. is more sensitive for all processes not mediated by photon e is more sensitive for processes mediated by photons The motivation is sufficiently strong that both experiments should be done Relative rates for e and me conv. would give information on underlying mechanism A significant rate for e with polarized muons could give additional information on mechanism M. Grassi – INFN Pisa Rome - November 7th , 2005

gm-2 and e+e- based prediction All E821 results were obtained with a “blind” analysis. ~2.7s difference with e+e- based SM prediction world average M. Grassi – INFN Pisa Rome - November 7th , 2005

Future gm-2 experiments Leading role of US groups E969 @ BNL 0.5 → 0.20 ppm (scientific approval but not funded) expected near-term improvement in theory, → the ability to confront the SM by ~ x 2 The next generation 0.20 → 0.06 ppm substantial R&D would be necessary M. Grassi – INFN Pisa Rome - November 7th , 2005

A gm-2 experiment to ~0.06 ppm? Makes sense if the theory can be improved to 0.1 ppm, which is hard, but maybe not impossible. With the present storage ring, we already have M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 The Physics Case Scenario 1 LHC finds SUSY MEG sees m → e g The trio will have SUSY enhancements to understand the nature of the SUSY space we need to get all the information possible to understand the nature of this new theory a la L. Roberts M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 The Physics Case Scenario 2 LHC finds Standard Model Higgs at a reasonable mass, nothing else … Then precision measurements come to the forefront, since they are sensitive to heavier virtual particles. μ-e conversion is especially sensitive to other new physics besides SUSY a la L. Roberts M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Muon EDM Present limit ~10-19 e-cm Could reach 10-24 at a high intensity muon source Developments and technology owned by US groups We could think of placing the ring not in the USA! J-PARC already was thought as an opportunity M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Muon channel Realm of an other WG … M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Conclusion  are sensitive probes of physics beyond the Standard Model SUSY theories require cLFV not far from present existing upper limits Strong case for experimental searches in all channels, together with improved measurement of gm-2 and mEDM +e+ results are expected in 2007 -e- conversion search is planned at the level of 10-18 -e- conversion is not accidental background limited could benefit of new high intensity pulsed beams M. Grassi – INFN Pisa Rome - November 7th , 2005

M. Grassi – INFN Pisa Rome - November 7th , 2005 Bibliography General J.Aysto et al. CERN-TH/2001-231 NuFact03 proceedings INFN WG 2004 SINDRUM coll., W Bertl et al. Nucl.Phys. B260(1988)1 SINDRUM2 coll., W Honecker et al. Phys.Rev.Lett. 76(1996)200 MECO coll., BNL proposal AGS P940 (1997) MEG coll., “The MEG proposal” (2002) m-A  t-A,X S.N. Gninenko et al.,Mod. Phys. Lett. A17 (2002) 1407, M. Sher et al.,Phys. Rev. D69 (2004) 017302) M. Grassi – INFN Pisa Rome - November 7th , 2005