Muonium – Physics of a Most Fundamental Atom Klaus Jungmann Kernfysisch Versneller Instituut & Rijksuniversiteit Groningen Simple Atomic System Atomic Theory Fundamental Constants Fundamental Symmetries Search for New Physics Atomic Physics at Accelerators Precision Measurements … Condensed Matter Physics Chemistry Low energy Muon Beams Muonium (M)

What is it ? What is it good for ? test of electromagnetic bound state theory test of electromagnetic bound state theory fundamental constants fundamental constants tests of fundamental symmetries tests of fundamental symmetries search for New Physics search for New Physics tool for condensed matter research tool for condensed matter research …… …… “Muonium is the bound state of a positive Muon and an Electron” positive Muon and an Electron” “point-like” particles “point-like” particles no (severe) strong interaction effects no (severe) strong interaction effects calculable to required accuracy calculable to required accuracy Muonium (M)

hydrogen-like atom but no strong interaction

Past of Muonium (Ground State Hyperfine Structure) Discovery of Muonium 1960 Hyperfine Structure addressed as an Important Quantity From: V. Telegdi, in: “A Festschrift for Vernon W. Hughes”, 1990 There was stimulating competition

Theorists are confident that muonium HFS Can be calculated to 10 Hz, if needed (Eides, Pachucki,…)  magnetic moment  , 

The worlds most intense quasi continuous muon source - the LAMPF Los Alamos Meson Physics Facility

Muonium Hyperfine Structure Solenoid   e    in SS Gated Detector MW-Resonator/Kr target Yale - Heidelberg - Los Alamos

Muonium Hyperfine Structure Solenoid   e    in SS Gated Detector MW-Resonator/Kr target Yale - Heidelberg - Los Alamos pulsed beam essential old Muonium freq. scan B scan

Results from LAMPF Muonium HFS Experiment measured: 12 = (35) Hz( 18 ppb) 34 = (43) Hz( 17 ppb) from Breit-Rabi equation: 12    exp = (53) Hz( 12 ppb)  theo = (520)(34)(<100) Hz (<120 ppb)  12      p = (37) (120 ppb) alternatively derived: m   m e = (24)(120 ppb)    ppb)

Results from LAMPF Muonium HFS Experiment measured: 12 = (35) Hz( 18 ppb) 34 = (43) Hz( 17 ppb) from Breit-Rabi equation: 12    exp = (53) Hz( 12 ppb)  theo = (520)(34)(<100) Hz (<120 ppb)  12      p = (37) (120 ppb) alternatively derived: m   m e = (24)(120 ppb)    ppb)

NEVIS CHICAGO-SREL LAMPF LAMPF latest experiment Quoted Uncertainty [kHz] Year History of Muonium Ground State Hyperfine Splitting Measurements

 -1 = (5)  -1 = X X (1) CODATA 2002

muonium and hydrogen hfs → proton structure

? m mm r 0 00 K KK || K     avg a | e a e a| avg g | e g e g| e r             CPTbreakb,a μμ Invariance LorentzbreakH,d,c,b,a μν μμ ? Lepton Magnetic Anomalies in CPT and Lorentz Non-Invariant Models CPT tests Are they comparable- Which one is appropriate  Use common ground, e.g. energies Leptons in External Magnetic Field Bluhm, Kostelecky, Russell, Phys.Rev. D 57,3932 (1998) For g-2 Experiments : Dehmelt, Mittleman,Van Dyck, Schwinberg, hep-ph/ μμ qAiiD 0D μ γ 5 γ μν id ν D μ γ μν ic μν σ H 2 1 μ γ 5 γ μ b μ γ μ am μ D μ (iγ equation DIRAC violating Lorentz and CPT generic    ψ ) 2 c l m a Δω l upspin E | l downspin E l upspin E| l r l 3 4b l a ω l a ω a Δω             avg ll 2 l c l a |aa| cm ω r     μ r e r      :: muonelectron CPT CPT – Violation Lorentz Invariance Violation What is best CPT test ? New Ansatz (Kostelecky) K 0  GeV/c 2 n  GeV/c 2 p  GeV/c 2 e-  GeV/c 2 Future: Anti hydrogen  GeV/c 2 often quoted: K 0 - K 0 mass difference ( ) e - - e + g- factors (2* ) We need an interaction with a finite strength ! What about Second Generation Leptons?

CPT and Lorentz Invariance from Muon Experiments Muonium: new interaction below 2 * GeV Muon g-2: new interaction below 4 * GeV (CERN) 15 times better expected from BNL V.W. Hughes et al., Phys.Rev. Lett. 87, (2001)

Present Status of Muonium Ground State Hyperfine Structure No Experimental Activities known at this time Refinement of Theory going on Refinement of Theory going one.g.  Eides, Grotch, “Three-Loop Radiative-Recoil Corrections to Hyerfine Splitting in Muonium”, Phys.Rev.D67, (2003) and hep-ph/ (2005) in Muonium”, Phys.Rev.D67, (2003) and hep-ph/ (2005)  Marciano, “Muonium Lifetime and Heavy Quark Decays”, hep-ph/ (2004) (2004) ... Exploitation of the Atom in Condensed Matter Science Exploitation of the Atom in Condensed Matter Sciencee.g.  Ivanter et al. “On the anomalous muonium hyperfine structure in silicon” J.Phys.: Condens. Matter 15, 7419 (2003) J.Phys.: Condens. Matter 15, 7419 (2003)  ….

NEVIS CHICAGO-SREL LAMPF LAMPF latest experiment Quoted Uncertainty [kHz] Year History of Muonium Ground State Hyperfine Splitting Measurements

Future Possibilities for Muonium Ground State Hyperfine Structure LAMPF Experiment limited by STATISTICS  more MUONS needed  factor > 100 over LAMPF – pulsed > 5*10 8  + /s  factor > 100 over LAMPF – pulsed > 5*10 8  + /s below 28 MeV/c below 28 MeV/c  new ACCELERATORS  J-PARC ?  Neutrino Factory ?  Eurisol ?  GSI ?  FNAL  ……..

What other experiments besides the Ground State Hyperfine Structure are possible ?

Gas Stop Gas Stop Yields up to 100% foreign gas effects Polarization up to 50% (B=0) 100% (B>>1T)  + +e   ++ Kr, Ar Beam Foil Beam Foil Muonium in Vacuo keV energy n=2 state populated fast muonium   + 50%  + e  1%  + e  e  0.01% ++ SiO 2 Powder SiO 2 Powder thermal Muonium in Vacuo M(2s) /M(1s) < Yields up to 12% Polarization 39(9)% velocity 1.5 cm/   ++ M Methods of Muonium Production

Completed Experiments on Muonium 1s-2s Interval Pioneering effort at KEK Pioneering effort at KEK ( Chu,Mills,Nagamine et al.) ( Chu,Mills,Nagamine et al.) Precision measurement at RAL Precision measurement at RAL ( Heidelberg – Oxford – Rutherford – Strathclyde – Siberia –Yale ( Heidelberg – Oxford – Rutherford – Strathclyde – Siberia –Yale Collaboration) Collaboration)

Muonium 1S-2S Experiment -.25 R  1S 2S 244 nm Energy -R  0    e   kin Laser Diagnostics   Detection   in  ee Target Mirror Heidelberg - Oxford - Rutherford - Sussex - Siberia - Yale

The most intense pulsed muon source – ISIS at the RAL Rutherford Appleton Laboratory

Muonium 1S-2S Experiment -.25 R  1S 2S 244 nm Energy -R  0    e   kin Laser Diagnostics   Detection   in  ee Target Mirror Heidelberg - Oxford - Rutherford - Sussex - Siberia - Yale

Muonium1s-2s At RAL

Results:  1s-2s = (9.1)(3.7) MHz  1s-2s = (1.4) MHz m    = (17) m e (0.8ppm) q     = [ (2.1) ] q e-  (2.2 ppb) exp theo

Future Possibilities for Muonium 1s-2s Interval No Precision Experiment Activities known at this time No Precision Experiment Activities known at this time Exploitation of Laser Spectroscopy to obtain Exploitation of Laser Spectroscopy to obtain “Slow Muons” Condensed Matter Science (K. Nagamine et Y Matsuda et al J. Phys. G: Nucl. Part. Phys. 29, 2039 (2003)

Future Possibilities for Muonium 1s-2s Interval RAL Experiment limited by STATISTICS RAL Experiment limited by STATISTICS  more MUONS needed  factor > 1000 over RAL – pulsed > 5*10 8  + /s below 28 MeV/c below 28 MeV/c  would enable cw laser spectroscopy ! (precision !)  new ACCELERATORS  J-PARC ?  Neutrino Factory ?  Eurisol ?  GSI ? .....

QED mm mm  , , g   + e -  HFS, n=1  QED corrections weak contribution  + e -  1S-2S m  QED corrections  g-2 hadronic contribution weak contribution New Physics

a  = a m ca m c e  B = aa pp aa pp  pp - Experiment: Fundamental Constants of Interest to g-2 Theory: * need  for muon ! * hadronic and weak corrections * various experimental sources of  better 100ppb>  need constants at very moderate *  no concern for (g-2)  even with recent corrections accuracy *  a and B (  p ) measured in (g-2)  experiment * c is a defined quantity * m  (   ) is measured in muonium spectroscopy (hfs) NEW 2000 * e  is measured in muonium spectroscopy (1s -2s) NEW 1999 *  p in water known >> probe shape dependence *  3He to  p in water >> gas has no shape effect being improved

 Any New Effort to improve significantly on the Muon Magnetic Anomaly will need better constants ! Where should they come from, if not from Muonium Spectroscopy ?

Muonium – Antimuonium Conversion up to Now Did first Search for Conversion Amato et al. Phys.Rev.Lett. 21, 1709 (1968) Predicted M-M Conversion Named System “Muonium” ?

The most intense continuos source of muons – the Cyclotron Facility at the PSI Paul Scherrer Institut

Present Activities concerning Muonium – Antimuonium Conversion No Experimental Activities known at this time No Experimental Activities known at this time Theory is proposing lots of models Theory is proposing lots of modelse.g.  Clark, Love “Muonium-Antimuonium Oscillations and Massive Majorana Neutrinos”, hep-ph/ (2003) hep-ph/ (2003)  Gusso, Pires, Pires, Rodrigues da Silva “Minimal Model, lepton Mixing and Muonium- Antimuonium Conversion”, hep-ph/ (2002) Muonium- Antimuonium Conversion”, hep-ph/ (2002)  Cvetic,Dib, Kim, Kim, “Muonium-Antimuonium Conversion in models with heavy neutrinos”, hep-ph/ (2005) hep-ph/ (2005)  Applequist, Christensen, Piai, Schrock “ Flavour-Changing Processes in Extended Technicolor”, Phys. Rev.D70, (2004) Phys. Rev.D70, (2004)  ….

Future Possibilities for Muonium – Antimuonium Searches PSI Experiment limited by STATISTICS  more MUONS needed  factor > 1000 over PSI – pulsed > 1*10 9  + /s  factor > 1000 over PSI – pulsed > 1*10 9  + /s below 28 MeV/c below 28 MeV/c  new ACCELERATORS  J-PARC ?  Neutrino Factory ?  Eurisol ?  GSI ?  FNAL .....

Old Muonium for Muonium-Antimuonium Conversion ? P(M)  sin 2 [const * (G MM /G F )*t]*exp[-  *t] Background  exp(- n  *t) ; n-fold coincidence detection For G MM << G F M gains over Background P(M) / Background  t 2 * exp[+(n-1)*  *t]  Pulsed ACCELERATOR

There is not only Muonium Spectroscopy waiting for a push by Intense Muon Beams

Summary Muonium has provided information on –QED –lepton flavor conservation –fundamental constants fine-structure constant  m  /m e   /  p – proton structure At a high-flux muon facility all of these could be improved.

Muon Experiments Possible at a CERN Neutrino Factory - Expected Improvements Muon Physics Possibilities at Any High Power Proton Driver i.e.  4 MW

< < < < Muon Physics Possibilities at Any High Power Proton Driver i.e.  4 MW K Jungmann 18-Apr-2001

J-PARC is one Possibility There are others as well: as well: Neutrino Factory ? Neutrino Factory ? Muon Collider ? Muon Collider ? GSI ? GSI ? …. ….

Thank You Vernon for providing us the perhaps most perhaps most Ideal Atom Muonium (M)