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MUON Physics Program at Fermilab

Dive into the forefront of muon physics research, exploring promising experiments to uncover charged lepton flavor violation and anomalous muon magnetic moments. Learn about the history, goals, and strategies in this PAC Presentation overview. Discover cutting-edge techniques and theoretical advancements that are reshaping the future of particle physics.

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MUON Physics Program at Fermilab

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  1. MUON Physics Program at Fermilab Eric Prebys, FNAL Summarizing steering committee working group, chaired by W. Molzon and A. de Gouvea E. Prebys - PAC Presentation

  2. Muon Physics at the Intensity Frontier • Two classes of muon experiments have been identified as particularly promising for an intensity-based program • m e conversion • A dramatic improvement in the search charged lepton flavor violation (CLFV) • Broadly sensitive to new physics • Complementary to proposed m eg searches (eg, MEG) • Can exploit voluminous work done for MECO proposal at BNL • Anomalous muon magnetic moment (g-2) • Already shows hint of possible new physics • Can transport apparatus from previous experiment at Brookhaven • Significant improvements in experimental technique and theoretical uncertainty E. Prebys - PAC Presentation

  3. m->e CLFV in the Standard Model • Forbidden in Standard Model • Observation of neutrino mixing shows this can occur at a very small rate • Photon can be real (m->eg) or virtual (mN->eN) First Order FCNC: Higher order dipole “penguin”: Virtual n mixing E. Prebys - PAC Presentation

  4. ? ? ? me Conversion vs. meg • We can parameterize the relative strength of the dipole and four fermi interactions. • This is useful for comparing relative rates for mNeN and meg Courtesy: A. de Gouvea MEG proposal Sindrum II MEGA E. Prebys - PAC Presentation

  5. History of Lepton Flavor Violation Searches 1 K0+e- K+++e- 10-2 - N  e-N +  e+ + e+ e+ e- 10-4 10-6 10-8 10-10 SINDRUM II 10-12 Initial MEG Goal 10-14 Initial mu2e Goal  10-16 10-16 19401950 1960 1970 1980 1990 2000 2010 E. Prebys - PAC Presentation

  6. Previous Limit on mNeN: Sindrum II High energy tail of coherent Decay-in-orbit (DIO) • Rate limited by need to veto prompt backgrounds! E. Prebys - PAC Presentation

  7. Mu2e (MECO) Philosophy • Eliminate prompt beam backgrounds by using a primary beam with short proton pulses with separation on the order of a muon life time • Design a transport channel to optimize the transport of right-sign, low momentum muons from the production target to the muon capture target. • Design a detector to strongly suppress electrons from ordinary muon decays ~100 ns ~1.5 ms Prompt backgrounds live window E. Prebys - PAC Presentation

  8. mu2e Muon Beam and Detector for every incident proton 0.0025 m-’s are stopped in the 17 0.2 mm Al target foils MECO spectrometer design E. Prebys - PAC Presentation

  9. Pre-Project X: “Boomerang” Scheme • Deliver beam to Accumulator/Debuncher enclosure with minimal beam line modifications and no civil construction. MI-8 -> Recycler done for NOvA Recycler(Main Injector Tunnel) New switch magnet extraction to P150 (no need for kicker) E. Prebys - PAC Presentation

  10. Staged Approach: Initial Goal • Exploit NOvA accelerator modifications and post-Run II availability of Accumulator and Debuncher rings to mount a m->e conversion experiment patterned after MECO • 4x1020 protons in ~2 years • Measure • Single event sensitivity of Rme=2x10-17 • 90% C.L. limit of Rme<6x10-17 • Improvement over existing limit of more than four orders of magnitude (one order of magnitude in effective mass reach) • ANY signal = Beyond Standard Model physics E. Prebys - PAC Presentation

  11. Example Sensitivities* Supersymmetry Compositeness Predictions at 10-15 Second Higgs doublet Heavy Neutrinos Heavy Z’, Anomalous Z coupling Leptoquarks *After W. Marciano E. Prebys - PAC Presentation

  12. Mu2e and Project X • The Project X linac would provide roughly a factor of ten increase in flux. • Or could allow this experiment to run concurrently with other experiments requiring similar intensity • Investigating scheme for proton delivery • Direct extraction from Recycler? • Injection into Accumulator, then manipulate as before? • Also investigating improvements to muon transport efficiency based on muon collider/neutrino factory R&D • The combination of increased flux and efficiency could potentially push the 90% C.L. sensitivity to ~10-18 E. Prebys - PAC Presentation

  13. Time Line

  14. Muon Anomalous Magnetic Moment (g-2) • To lowest order, the muon magnetic moment (g) is 2 • g is perturbed by contributions from virtual loops, from both the Standard Model and (possibly) beyond. • The calculation and measurement of the “anomalous magnetic moment” stands as one of the most precise tests of the Standard Model E. Prebys - PAC Presentation

  15. p p g m Z m p p B Weak Had LbL Had VP Had VP QED 2006 plot KEY REGION Standard Model Contributions to am E. Prebys - PAC Presentation

  16. New physics enters through loops … e.g., SUSY R-parity conserving Supersymmetry (vertices have pairs) And the diagrams are amplified by powers of tanb(here linearly) E. Prebys - PAC Presentation

  17. e wa Momentum Spin Measurement of g-2 • am is determined from the ratio of the muon precession frequency (wa) and the magnetic field (B). E. Prebys - PAC Presentation

  18. Status of g-2 Theory+exp. input TIME Compare K. Hagiwara, A.D. Martin, Daisuke Nomura, T. Teubner Rep.Prog.Phys. 70, 795 (2007). E. Prebys - PAC Presentation

  19. Improvements to g-2 at Fermilab • Increase muon flux with better beam optics • Decrease p contamination with long transport channel • Improve injection kicker to increase number of stores E. Prebys - PAC Presentation

  20. Booster-era Beam Transfer Scheme Ankenbrandt and Popovic, Fermilab g-2 Rare Kaon Decays m Test Facility Alternative ? E. Prebys - PAC Presentation

  21. Geant simulation using new detector schemes Event Method Same GEANT simulation Energy Method A complementary method of determining wa is to plot Energy versus Time E. Prebys - PAC Presentation

  22. Staged Approach at FNAL • Phase 1: m+ measurement to 0.1 ppm statistical • Requires Nova type upgrades, beam manipulations and ~4x1020 p • Can do in pre Project X era • Phase 2: m- measurement to 0.1 ppm (or lower) • Requires many more protons due to xsection for p- • Would benefit from Project X • Phase 3: All “integrating” with much higher proton beam and restricted storage ring acceptance to lower systematics • Requires Project X E. Prebys - PAC Presentation

  23. Systematic errors on ωa (ppm) E. Prebys - PAC Presentation

  24. E821 ωpsystematic errors (ppm) Future E. Prebys - PAC Presentation

  25. Typical CMSSM 2D space showing g-2 effect Future Dam = 295 ± 39 x 10-11 Present: Dam = 295 ± 88 x 10-11 Here, neutralino accounts for the WMAP implied dark matter density scalar mass 2s 1s Excluded for neutral dark matter gaugino mass With new experimental and theoretical precision and same Dam This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive Topical Review: D. Stöckinger hep-ph/0609168v1 E. Prebys - PAC Presentation

  26. Conclusion • Precision muon measurements offer powerful tools for the investigation of physics beyond the Standard Model. • Both the me conversion experiment and the g-2 measurement fit well into an intensity-based program at Fermilab. • These programs have the potential for a staged approach, beginning in the NOvA era and expanding in the Project X era. E. Prebys - PAC Presentation

  27. Backup SlideS E. Prebys - PAC Presentation

  28. What is the Competition? • MEG experiment (running) at Paul Scherrer Institute: m→eg to ~10-13 • Difficult to improve beyond that (perhaps to 10-14) due to accidental backgrounds • Reprise of MECO/mu2e at BNL • Fermilab has better time structure, duty cycle, running time per year, higher intensity • COMET at JPARC • Muon beam flux, time structure similar to MECO design • sensitivity below 10-16 • Detectors displaced from stopping target to reduce rates • PRISM/PRIME at JPARC • Very different muon beam: FFAG storage ring forphase rotation, very intense pulses at low frequency (<1kHz) • Very small, narrow momentum spread beam, thintarget, detector arrangement similar to COMET • Would require new building, technical advances • Prime disadvantage of both COMET and PRISM/PRIME is conflict with running neutrino beam William Molzon, UC Irvine Muon Physics at Fermilab

  29. Examples with k>>1 (no meg signal): Leptoquarks Z-prime Compositeness Heavy neutrino Sensitivity (cont’d) SU(5) GUT Supersymmetry:  << 1 Littlest Higgs:   1 Randall-Sundrum:   1 R(mTieTi) R(mTieTi) 10-10 MEG 10-10 10-12 10-12 10-14 10-14 10-16 10-16 mu2e 10-9 10-11 10-11 10-15 10-13 10-13 Br(meg) Br(meg) E. Prebys - PAC Presentation

  30. Consider the physics message carried by Dam(expt – thy) ~ 300 x 10-11 at present (E821: ±88 x 10-11 ) and future (E969: ±39 x 10-11 ) uncertainties in DamMuon g-2, like other precision measurements, has powerful discriminating input Snowmass Points and Slopes: 10-11 units Compare to present Dam =295 ± 88 293 318 16.5 135 490 86 169 237 173 -90 Next stage to dDam < ±39 http://www.ippp.dur.ac.uk/~georg/sps/sps.html

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