1. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Lecture II: Neutrons beyond the SM Motivation Right-handed W bosons –Classical theory of neutron decay –Search for traces of W R in decay asymmetries CP violation beyond the SM –Search for CP violation in neutron decay –Electric dipole moments –Measurement of the neutron EDM Baryon number violation –Scenarios of Baryon number violation –Search for neutron-antineutron oscillations

2. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutron Decay beyond the Standard Model (broken) SU(2) L  SU(2) R  deviation from maximal parity violation (V+A)  additional phases for CP violation Exotic (non V,A) couplings  scalar, tensor, or pseudo- tensor interactions Standard Model SU(2) L (V-A interaction) Leptoquark exchange  additional phases for CP violation  exotic couplings

3. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutrons and New Physics Search for processes which are unobservably small in the SM are not allowed in the SM deviate observables from the SM values CP violation Electric dipole moment Triple correlations D or R of the decay products Baryon number violation Neutron-Antineutron- Oscillations Right-handed currents Neutrino asymmetry B CP-violating phases (d n, D, R) Unification scenarios Left-right symmetric models New interactions (SuSy…)  new phases Baryon asymmetry

4. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Why should we search for CP or B violation? Baryon Asymmetry in the Universe Baryon number violation C and CP violation Thermal non-equilibrium A.D. Sakharov: JETP 5 (1967) 24 Standard Model B violation in sphalerons (B–L conserved) C violation in weak interaction CP violation in Kaons, B mesons Thermal non-equilibrium in electroweak phase transition But Not enough CP violation for Baryogenesis Higgs boson too heavy to create first order phase transition  New physics required

5. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Classical Theory of Weak Decay Standard Model: General Hamiltonian:

6. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Find the Parameters… J.D. Jackson et al.: Phys. Rev. 106 (1957) 517 Surviving in the SM:

7. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Find the Parameters… or T violation beyond SM Test for right handed currents

8. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Example: Right-Handed Currents Standard Model (V-A) + SM + (V+A)-contributions and ft(0 +  0 + ) and  n B = 0.983(4) [PDG 2004] From K  3 , K  2  B = 0.983(2) [just for fun] From K  3 , K  2  and  n B = 0.983(4) [PDG2004] From K  3 , K  2  Mainly B Mainly A

9. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Proton detection: E p < 750 eV  acceleration prior to detection  special low noise detectors needed Challenges in Neutron Decay Experiments Electron detection: E e < 780 keV  typical energy of gamma background  sophisticated techniques difficult Life time:  =885.7(8) s Velocity: 1000 m/s  only 10 -7 of the passing neutrons decay, low statistics  all others can create background

10. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutron Decay and Right-handed Currents Neutrino asymmetry World average: B = 0.983(4) Serebrov et al, JETP 86 (1998) 1074 B=0.9801  0.0046

11. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner How to Improve? 2  2  spectrometer Better statistical sensitivity Backscattering suppressed Solid angle: Magnetic field Detector function: Electron and proton in same detector

12. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner First Experiment (2001) E p < 750 eV from decay ~20 keV after acceleration) (4-5)  20 keV in detector B=0.967  0.006 stat  0.010 sys Main limitations Polarisation Instable high voltage Scintillator after pulses High-voltage related background M. Kreuz et al, PLB 619 (2005) 263 Serebrov et al, JETP 86 (1998) 1074

13. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutrons and CP (T) Violation Triple correlations in the decay D SM  10 -12 D FSI =1.1·10 -5 D exp  10 - 3 R SM  10 -12 R FSI =1·10 -3 R exp(goal)  5  10 - 3 d SM =10 -33 …10 -31 e  cmd exp  10 -25 e  cm Electric dipole moment

14. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner R & D R coefficientD coefficient P. Herczeg, Prog. Part. Nucl. Phys. 46 (2001) 413. P conserving  sensitive to V,A type T violating d  ue e interactions P violating  sensitive to S,T type T violating d  ue e interactions Limits from P,T violating electron- nucleon interaction more stringent EDM more stringent for left-right, exotic fermions D more stringent for leptoquark New T violation may contribute on the tree level  theoretical uncertainties more reliable than for loop type contributions Left-right Exotic fermionsLeptoquark Present sensitivity for D tests M X in TeV range

15. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Principle Set-Up Measurement of D P violation  Asymmetry with spin-flip Breaking of detector symmetry  Systematic effects D = 0 in SM

16. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Measurement of D L.J. Lising et al, PRC 62 (2000) 055501. Optimise for Systematics Optimise for Statistics D = (–2.8  6.4 stat  3.0 syst )·10 -4 T. Soldner et al, Phys. Let. B 581 (2004) 49. D = (–6  12 stat  5 syst )·10 -4

17. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner D & d n P. Herczeg, Prog. Part. Nucl. Phys. 46 (2001) 413.

18. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Electric Dipole Moments Comparable sensitivity to fundamental CP violation, e.g. superpartner masses and CP-violating phases – complementary observables Probe flavour-diagonal CP violation (negligible in the SM) Schiff’s theorem: Electric fields will be shielded by redistribution of electrons – no EDM of atoms Paramagnetic atoms and molecules d( 205 Tl) < 9  10 -25 e cm Incomplete due to relativistic effects, net enhancement of atom EDM relative to electron EDM CP from electron EDM Diamagnetic atoms (L = 0) d( 199 Hg) < 2  10 -28 e cm Incomplete due to finite size of nucleus; atom EDM still suppressed compared to nucleus EDM, but not fully CP from CP-odd nucleon- nucleon interactions Hadrons, in particular nucleons d n < 6  10 -26 e cm CP in quark sector M. Pospelov & A. Ritz: hep-ph/0504231 W. Bernreuther & M. Suzuki: Rev. Mod. Phys. 63 (1991) 313

19. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Electric Dipole Moments Probe flavour-diagonal CP violation (negligible in the SM) Paramagnetic atoms and molecules d( 205 Tl) < 9  10 -25 e cm EDM of unpaired electron Contributions from CP-odd electron-nucleon interactions (e.g. CP violation in Higgs sector) Apart from this insensitive to QCD effects Enhancement of d e  500, Even larger for molecules (e.g. YbF, PbO) Diamagnetic atoms (L = 0) d( 199 Hg) < 2  10 -28 e cm CP-odd nuclear moments, caused by CP-odd nucleon- nucleon interactions or nucleons EDM In general less important: d e, electron-nucleon interaction Nuclear moment calculations very difficult; suppression of individual contribution by factor  100 due to cancellations Hadrons, in particular nucleons d n < 6  10 -26 e cm d n composed of contributions from quarks and gluons No additional atomic or nuclear physics M. Pospelov & A. Ritz: hep-ph/0504231

20. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Electric Dipole Moments Probe flavour-diagonal CP violation (negligible in the SM) Paramagnetic atoms and molecules d( 205 Tl) < 9  10 -25 e cm Diamagnetic atoms (L = 0) d( 199 Hg) < 2  10 -28 e cm Hadrons, in particular nucleons d n < 6  10 -26 e cm S.M. Barr: Int. Journ. Mod. Phys. A 8 (1993) 209 eelectron q quark G gluon N nucleon d EDM d C chromo EDM MQMmagnetic quadrupole moment At scales up to 10 3 TeV M. Pospelov & A. Ritz: hep-ph/0504231

21. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutron and Electron EDM EDMs in the SM Single CP-violating invariant: J CP = Im(V tb V td * V cd V cb * )  3  10 -5  Four electroweak vertices needed Quark & nucleon EDMs All EDM vanish on two- loop level Three-loop for quark EDM d q CKM  10 -34 e cm Main contribution for d n from four-quark operator, enhanced by long-distance effects (pion loops) d n CKM  10 -32 e cm Lepton EDMs Via diagrams with closed quark loops Non-vanishing only at four-loop level d e CKM  10 -38 e cm CKM-like phases in lepton sector, Majorana d e SeeSaw < 1.5  10 -43 e cm (up to 10 10 enhancement by fine-tuning) M. Pospelov & A. Ritz: hep-ph/0504231 10 -32 10 -20 10 -22 10 -24 10 -30 SUSY 10 -34 10 -36 10 -38 Left-Right Multi Higgs Standard Model Electro- magnetic Neutron d e = (6.9±7.4)  10 -28 e cm d n = –(1±3.6)  10 -26 e cm Electron

22. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner CP Problems Strong CP ProblemSuSy CP Problem CP violating contribution to QCD Lagrangian suppressed to  < 10 -9 – why? CP violating phases are small Or Soft-breaking masses significantly larger than 1TeV Proposals: Axions CP or P exact symmetry at higher energy scale (e.g. some LR models) Proposals: Heavy superpartners Assume exact CP in soft- breaking sector Accidental cancellations M. Pospelov & A. Ritz: hep-ph/0504231

23. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Measuring the Neutron EDM – Principle

24. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Measuring the Neutron EDM – Resonance Method 4. 3. 2. 1. Free precession... Apply  /2 spin flip pulse... “Spin up” neutron... Second  /2 spin flip pulse. B Sensitivity  Visibility of resonance fringe EElectric field strength TTime of free precession NNeutron number

25. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner The Rutherford-Sussex-ILL-Experiment N S Four-layer mu-metal shield High voltage lead Quartz insulating cylinder Coil for 10 mG magnetic field Upper electrode Main storage cell Hg u.v. lamp PMT to detect Hg u.v. light Vacuum wall Mercury prepolarising cell Hg u.v. lamp RF coil to flip spins Magnet UCN polarising foil UCN guide changeover Ultracold neutrons (UCN) UCN detector  = 0.5 E = 4.5 kV/m T = 130 s (time of cycle: 210 s) N = 13000 per bunch P.G. Harris et al. : NIM A 440 (2000) 479 Sensitivity improved steadily, 2003:

26. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Rutherford-Sussex-ILL-Experiment – Hg Magnetometer In-situ measurement of magnetic field by observing precession of 199 Hg atoms Precision: 2 nG per cycle (Neutron counting error: 10 nG per cycle)

27. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Systematic Effects Leakage currents –Create additional magnetic field and precession –I leak  1nA  effect small Sparks –Automatically identified and rejected by magnetometer v  E effect –Magnetic field in neutron rest frame due to electric field –Averages out if there is no net rotational motion of neutrons Effects estimated to be below 10 -26 e cm P.G. Harris et al. : PRL 82 (1999) 904 Geometric phases –Caused by v  E effect in combination with gradient of B –Works differently on n and Hg (velocity, distribution) –On Hg: 1  10 -26 e cm (for 1nT/m) –On n: -1  10 -27 e cm (for 1nT/m)  Transfer more dangerous than direct effect on d n –Correction possible  But dangerous for future projects M. Pendlebury et al. : PRA 70 (2004) 032102

28. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutron EDM – Projects New UCN sources Superfluid 4 He RAL-Sussex-ILL LANCSE / SNS Solid D 2 Paul Scherrer Institut FRM II Munich Gain factors of  10 3 New n-EDM Projects RAL-Sussex-ILL: Cryo-EDM PSI-IN2P3-... LANSCE / SNS Attempted final precisions:  10 -28 e  cm RAL-Sussex-ILL Higher fields inside 4 He New magnetometers

29. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner An Alternative – CrystalEDM? Not competitive with proposed UCN projects, but with existing one Completely different systematics, does not require magnetic field Idea: Use high electric field inside some crystals up to 10 9 V/cm for certain crystals and higher density of cold neutrons Prestudies at PNPI: Fedorov, Voronin et al.

30. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Neutrons and Baryon Number Violation Motivation– needed to create Matter-Antimatter-Asymmetry in Universe – implied by GUTs, SuSy, Left-Right-symmetric models Classes of B violation |  B| = 1 p  leptons, n  leptons, p  mesons, n  mesons Probes high scales (GUT) |  (B – L)| = 0 |  B| = 2 p + n  mesons (  s) n  n Probes intermediate scales |  (B – L)| = 2

31. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Models with n  n Traditional Large extradimsSuSy seesaw “Large class” of seesaw models for masses allow observable n n Parity and (B – L) breaking close to conventional GUT scale 2  10 16 GeV Majorana R mass and n n created by same operators K.S. Babu & R.N. Mohapatra: Phys. Lett. B 518 (2001) 269 S. Nussinov & R. Shrock: Phys. Rev. Lett. 88 (2002) 171601 Consider 2 large extra dimensions Fermion wave- functions localised Effective scale M I for n n: Interesting for GUT breaking schemes, e.g. (embedded in SO(10)): Relates (B – L) breaking, parity breaking, and small neutrino masses: n n observable for scale  100TeV Today Neutrinos very light, required mass scale makes n n unobservable in these models Review: R.N. Mohapatra: NIM A 284 (1989) 1

32. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Phenomenology of n n Free neutrons Numbers 0.1s free flight (100m at 1000 m/s) Flux 10 11 n/s Observation time 1 day Neutrons in Medium / Field B < 10nT (0.1mG) Vacuum < 10 -4 mbar Inside nucleus: V  500 MeV (could also change  m)

33. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner n n – Experiment M. Baldo-Ceolin et al: Z. Phys. C 63 (1994) 409 10 11 n/s  600 m/s, 81 m free flight B < 10 nT (Mumetal) p < 10 -4 mbar 200  m C target Effective running time 280 days Analysis by -event visible energy -TOF between SCs -vertex reconstruction

34. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Other Methods n n in Nuclei Inside nucleus: V  500 MeV Interaction can change  m  Require model-dependent corrections for nuclear effects Soudan 2 iron tracking calorimeter (5.6 kT  yr): J. Chung et al.: Phys. Rev. D 66 (2002) 032004 T Fe > 7.2  10 31 yr Background limited! Cold neutronst  0.1 s UCNst  800 s n n with UCNs? But: n phase is absorbed and reset in wall collision 0.1s free flight (100m at 1000 m/s) Flux 10 11 n/s Observation time 1 day Very optimistic Numbers 0.2s free flight (1m at 5 m/s) 800 s storage Density 10 4 cm -3, 1m 3 Observation time 1 day Same number of neutrons/s in very opti- mistic UCN scenario, only gain: (t free /t) 1/2

35. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner Summary – Neutrons beyond the Standard Model Precise absolute measurements of SM observables and consistency checks –Beta asymmetry, Antineutrino asymmetry, Lifetime  Search for right-handed currents below 1TeV Search for effects unobservably small in the SM (deviations from 0) –CP violation in the decay  Search for leptoquarks (up to 10 TeV) –CP violation in electric dipole moment  Search for new phases due to SuSy, LR, exotic fermions (1 to 10 3 TeV) Search for processes forbidden in the SM –Neutron-antineutron oscillations  Test of intermediate unification (B-L, LR) scale at 100TeV Nothing found yet, but this is already something…

36. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner The Neutron Guide to the Universe New PhysicsStandard Model Temperature 10 19 GeV Planck GUTs - - Inflation Electroweak Chiral transition Nucleon freeze out Nuclear freeze out Atomic freeze out Galacticfreeze out 10 -43 s 1 s Time 10 -11 GeV 10 -35 s10 -12 s10 5 y10 9 ytoday Diagram from D. Dubbers Neutron energies: peV…meV Decay energy: 780 keV Instead of E   E/E  0

37. Particle Physics with Slow Neutrons II LNGS Summer Institute, September 2005Torsten Soldner The Neutron Guide to the Universe  Gravitational/inertial mass gMagnetic monopole moment d n Electric dipole moment  nn Neutron-antineutron oscillation time  CP violating phase in decay m W,  W R -W L mixing parameters q n Neutron charge a WM Strength of weak magnetism Ratio of axial vector to vector coupling  N Nucleon-neutrino scattering cross section N Number of light neutrino families V ud Quark mixing element  pp Weak interaction in proton-proton interaction  n Electric polarisibility of the neutron A , P  Parity violating correlations in n-Nucleon and n-Nucleus interactions  Fine structure constant