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Status of a Next-generation Muon g-2 Experiment David Hertzog, Illinois

Status of a Next-generation Muon g-2 Experiment David Hertzog, Illinois. In the LHC era, the motivation will be about precision input to pin down the parameters of a New Standard Model. hertzog@uiuc.edu. Low Energy Precision Electroweak Physics in the LHC Era. UED.

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Status of a Next-generation Muon g-2 Experiment David Hertzog, Illinois

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  1. Status of a Next-generation Muon g-2 ExperimentDavid Hertzog, Illinois • In the LHC era, the motivation will be about precision input to pin down the parameters of a New Standard Model hertzog@uiuc.edu Low Energy Precision Electroweak Physics in the LHC Era

  2. UED Here is an example, related to g-2 SUSY SUSY Extra Dimensions The future am measurement will separate the two models by more than 7 standard deviations and thus allow for a clear decision in favor of one of them The quest for new physics understanding requires different tools • LHC: direct search for new particles • But, what new physics will they reveal? • Precision measurements: • Lepton flavor violation (m, t) • EDMs of e, n, atoms, etc. • Rare decays • 0nbb • Unitarity tests • Muon g-2 Consider a post-LHC world with many new mass states found

  3. Standard Model Our Expt. Status of experiment / theory comparison • Key points: • Theory: 0.48 ppm • Experimental 0.54 ppm (0.46 ppm stat; 0.31 ppm syst.) • Dam(expt-thy) = (297±88) x 10-11 (3.4 s) deRafael, Glasgow MDM Arguably, strongest experimental evidence of Physics Beyond Standard Model

  4. p p g m Z m p p B Weak Had LbL Had VP Had VP QED 2006 plot KEY REGION g ≠ 2 because of virtual loops, many of which can be calculated very precisely A significant amount has happened in 2008; Lee Roberts will update us

  5. g m Z m p p p p B Weak Had LbL Had LbL QED Had VP Had VP g ≠ 2 because of virtual loops, many of which can be calculated very precisely • Hadronic Light by Light has a 36% relative uncertainty !! ~ 0.34 ppm • Leading contribution must be positive • But, then we need a hadronic model • Many constraints, but can we achieve 15% relative error ? • THIS IS A CHALLENGE TO NUCLEAR THEORISTS

  6. 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)

  7. Typical CMSSM 2D space showing g-2 effect(note: NOT an exclusion plot) Present: Dam = 297 ± 88 x 10-11 Future Dam = 297 ± 39 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

  8. Expt The Snowmass Points and Slopes give reasonable benchmarks to test observables with model predictionsMuon g-2 is a powerful discriminatorno matter where the final value lands!! Future? Model Version SPS Definitions

  9. Suppose the MSSM reference point SPS1a* is realized and parameters determined by global fit (from LHC results) • sgn(m) can’t be obtained from the collider • tanbcan’t be pinned down by collider Possible future “blue band” plot, where tan β is determined from aμ. D. Stockinger * SPS1a is a ``Typical '' mSUGRA point with intermediate tanb = 10 *Snowmass Points and Slopes: http://www.ippp.dur.ac.uk/~georg/sps/sps.html

  10. A next-generation experment is about the “precision”, not the absolute value. At the Galveston Long Range Plan meeting, we were encouraged to design a “legacy” experimentConsider 0.14 ppm overall level … x4 better • E821 final error: • ± 0.48 ppm statistical • ± 0.27 ppm systematic Need 21 x more muons Must reduce systematics Very challenging TODAY I update our progress, which might be called g-2FiNALe for reasons you will soon see

  11. Dam improvement requires both experimental and theoretical progress units: x 10-11 This would get to ~9s Combined Error Experimental Error Actual path ? Theory Error

  12. e Momentum Spin The experimental goal will be ~15 x 10-11

  13. A next-generation (g-2)m experiment will use the BNL Storage Ring* *However, creative ideas from Saito-san et al do consider something radically different

  14. wa 1 ppm contours The anomaly is determined by a ratio of two precision measurements:waand B(and some knowledge of the muon orbit) Improving here requires greater statistics … x 21 (to be discussed) And, reducing background and controlling fit parameters from beam motions B More uniform field in re-shimming effort. Improved procedure to calibrate and measure field – using pNMR; Future “contours” will require sub-ppm lines

  15. NA2 2.5 ns samples N A <A>=0.4 A classic “event” is an isolated electron above a threshold. e+

  16. Then, to accept the higher rate, changes in the experiment are required; e.g., 4 Segmented detectors The new BNL experiment identified some obvious places to improve the muon transmission and to prepare for higher rate Open inflector 2 1 Beamline changes 3 Improve kicker

  17. It is instructive to understand the muon production, first with the standard “forward-decay” beam The FLASH is a limiting factor to just “turning up the rate” for any new expt. Survive momentum selection Pions @ 3.15 GeV/c Decay muons @ 3.094 GeV/c The hadronic flash background limits fit start time Far side Near inflector Pedestal vs. Time

  18. p m Muon Accumulator Ring MAR How to get more muons AND avoid the flash • Take the 0-degree forward muons • High polarization, highest yield • Long beamline to remove flash by pion decay • “Recycle” by muon accumulator ring (MAR) • Very long beamline • Take 180-degree “backward” muons • High polarization (reversed), slightly smaller yield • Intrinsically, no flash because of p/m momentum difference

  19. Phil Pile suggested a dogbone instead … There’s actually space for this kind of thing in the parking lot area

  20. How long? Removed pions Got muons Ideal…

  21. Two major new projects at FNAL m e conversion g-2 Mu2e FiNALe

  22. Gives 18 Hz of ring fills BNL was 4.4 Hz Intensity being studied, but expect 1year run will achieve the x21 statistics goal Most items are costed Including moving the ring Goal is < $20 M Target area least understood We are vigorously exploring plan now for a “next-generation” experiment at FNAL

  23. pbar target 8 GeV/c protons not 120 GeV as is now s(p) & 3.1 GeV/c Not 24 GeV (~3 lower) Li lens recycling time issue Pion to muon decay line optics New building required for ring Use pbar complex as an 800 m long “dogbone” beamline

  24. Opening the inflector ends should increase muon transmission by about ~x2 Present: CLOSED End Proposed: OPEN End

  25. cyclotron period This kick affects the storage efficiency IDEAL kick  8% REAL kick  3 % ?? Would prefer a taller, narrower kick if that can be achieved Improvements in the storage ring kicker are (technially) challenging, but essential. Present one underkicks and lasts too long.

  26. Segmenting detectors will reduce pileup. New W-SciFi calorimeter built and tested • 20-fold segmentation • 0.7 cm X0 • 12%/Sqrt(E) • Greatly constrained space

  27. 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

  28. We can also improve the Muon EDM by as much as a factor of 100 at the same time • Three methods with ~equal sensitivities, but one was limited by statistics and the others have hit a systematic wall Next E821 paper • A x24 modern installation of this idea could bring in >10,000 more events of up going vs down going tracks

  29. Conclusions: • Physics motivation continues to be strong • But, see other talks if you have any doubt • https://www.npl.uiuc.edu/twiki/bin/view/NewG2/WebHome • Realistic possibilities at FNAL match next-generation experimental demands for “legacy” type effort • Aim to write a proposal by Spring • Looking for people to sign on and take on part of this effort • We’ll discuss more organizational details on Thursday • Meanwhile, SM must and will continue to evolve with, hopefully (!) more assuring consistency • HVP … data driven … but not settled within errors of measurements • HLbL … theory driven … while leading term verified, smaller contributions treated differently • Lattice, other original efforts badly needed

  30. SPS points and slopes • SPS 1a: ``Typical '' mSUGRA point with intermediate value of tan_beta. • SPS 1b: ``Typical '' mSUGRA point with relatively high tan_beta; tau-rich neutralino and chargino decays. • SPS 2: ``Focus point '' scenario in mSUGRA; relatively heavy squarks and sleptons, charginos and neutralinos are fairly light; the gluino is lighter than the squarks • SPS 3: mSUGRA scenario with model line into ``co-annihilation region''; very small slepton-neutralino mass difference • SPS 4: mSUGRA scenario with large tan_beta; the couplings of A, H to b quarks and taus as well as the coupling of the charged Higgs to top and bottom are significantly enhanced in this scenario, resulting in particular in large associated production cross sections for the heavy Higgs bosons • SPS 5: mSUGRA scenario with relatively light scalar top quark; relatively low tan_beta • SPS 6: mSUGRA-like scenario with non-unified gaugino masses • SPS 7: GMSB scenario with stau NLSP • SPS 8: GMSB scenario with neutralino NLSP • SPS 9: AMSB scenario SPS PLOT www.ippp.dur.ac.uk/~georg/sps/sps.html

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