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- LFV and related topics

- LFV and related topics. 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 m LFV.   x x ~. Examples of CLFV processes. -LFV 3e e NeN’ ee.

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- LFV and related topics

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

  2. 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 x ~ M. Grassi – INFN Pisa Rome - November 7th , 2005

  3. Examples of CLFV processes -LFV 3e e 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

  4. Physics motivation Charged Lepton Flavour Violation (CLFV) processes, like meg , meee , meconversion, and also teg , t mg , 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 mechanismmay 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 experimentallyaccessible M. Grassi – INFN Pisa Rome - November 7th , 2005

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

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

  7. SUSY indications for meg LFV induced by finite slepton mixing through radiative corrections • SUSY SU(5) predictions BR (meg)  10-14  10-13 • SUSY SO(10) predictions BRSO(10) 100 BRSU(5) Experimental limit 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

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

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

  10. SU(5) LFV ratios 10-11 m<0 m>0 On large classes of SUSY-GUT BR(m-e conv) 10-2BR(meg) BR(m3e)10-2BR(meg) BR(t mg)10+5BR(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

  11. 103 BR(meg) x 1012 10-2 10-2 102 BR(tmg) x 108 CLFV comparison 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

  12. Predictions ? • Huge spread of SUSY prediction 10-12 – 10-19 • In R-violating SUSY the dominant process are m3eand 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

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

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

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

  16. +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 6x106m+/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

  17. +e+e+e- : future • SINDRUM: sensitivity  10-12 background  10-13 • A new experiment should aim to a sensitivity: B  10-16 would require 109m+/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

  18. +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

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

  20. +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

  21. qeg = 180° e+ +g Ee= Eg=52.8MeV +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 fore+ momentum • Scintillation counters for e+ timing M. Grassi – INFN Pisa Rome - November 7th , 2005

  22. +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 M. Grassi – INFN Pisa Rome - November 7th , 2005

  23. +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

  24. Detector parameters Signal Single Event Sensitivity  410-14 Cuts at 1,4FWHM  310-14 Backgrounds  310-15 +e+ : MEG sensitivity summary 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

  25. Revised document now LoI Proposal Planning R & D Assembly Data Taking 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 +e+ : MEG time profile 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

  26. +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

  27. +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

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

  29. -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 (~ 1013m/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

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

  31. -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

  32. -e- : SINDRUM II result SINDRUM II parameters • beam intensity 3x107m-/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

  33. -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

  34. -e- : PRISM beam • Muon momentum spread reduction by phase rotation down to 2  3 % FWHM • Intensity  1012m/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 besensitive to m  e conversion with SES ~ 6x10-19 BR ~ 10-18 Phase rotation concept M. Grassi – INFN Pisa Rome - November 7th , 2005

  35. -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

  36. -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

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

  38. 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

  39. 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

  40. 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

  41. 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

  42. 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

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

  44. 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 limitedcould benefit of new high intensity pulsed beams M. Grassi – INFN Pisa Rome - November 7th , 2005

  45. 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

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