It may be that the next exciting thing to come along will be the discovery of a neutron or atomic or electron electric dipole moment.

Transcription

1 It may be that the next exciting thing to come along will be the discovery of a neutron or atomic or electron electric dipole moment. These electric dipole moments... seem to me to offer one of the most exciting possibilities for progress in particle physics. - S. Weinberg 1

2 EDM Searches Why search for permanent electric dipole moments? How to measure EDM? Which systems are studied experimentally? What are the fields involved? What are the technologies involved? What is the present status? What will come next? 2

3 EDM Searches Why search for permanent electric dipole moments? CP-violating and very small in the Standard Model expect clean signals of New Physics: discovery potential in some BSM scenarios the best or only hope highly sensitive techniques available or being developed multiple complementary systems can help unravelling the underlying theory highly complementary to collider physics How to measure EDM? Which systems are studied experimentally? What are the fields involved? What are the technologies involved? What is the present status? What will come next? 3

4 EDM Searches Why search for permanent electric dipole moments? How to measure EDM? search for an interaction of the spin with the electric field Which systems are studied experimentally? many: particles, nucleons, nuclei, atoms, molecules, solids What are the fields involved? many: molecular, atomic, neutron, nuclear, particle, solid state, accelerator physics, surface science, chemistry,... What are the technologies involved? many: particle&neutron sources, radioactive ions, exotic molecules, laser, trapping, high voltage, magnetometry, magnetic shields, unprecedented magnetic field control, new materials,... What is the present status? new results further squeeze BSM parameter space many new projects started during the last few years What will come next? some results in the next couple of years major improvements within a decade 4

5 ... ideally, I should now cover everything (which doesn t work)... let s start at the beginning: 5

6 Nature has probably violated CP when generating the Baryon asymmetry!? Observed*: _ (n B -n B ) / n = 6 x γ SM expectation: _ (n B -n B ) / n γ ~ Sakharov 1967: B-violation C & CP-violation non-equilibrium [JETP Lett. 5 (1967) 24] * WMAP + COBE, 2003 n B / n γ = (6.1 ± 0.3 ) x

7 Nature has probably violated CP when generating the Baryon asymmetry!? New theories provide the CP-violation to describe Nature Sakharov 1967: B-violation C & CP-violation non-equilibrium [JETP Lett. 5 (1967) 24] 7

8 Nature has probably violated CP when generating the Baryon asymmetry!? New theories provide the CP-violation to describe Nature Experiments must access with high sensitivity CP-violating observables Sakharov 1967: B-violation C & CP-violation non-equilibrium [JETP Lett. 5 (1967) 24] 8

9 EDM and symmetries + _ P _ + T + _ A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau 9

10 Klaus Kirch 10 St. Petersburg FL, May 30, 2012 ( ) H B σ σ) ( µ E σ σ) ( d TH H B σ σ µ E) ( σ σ d PH B σ σ µ E σ σ d H + = + = + = P T EDM and symmetries A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau

11 How to measure the neutron (or other) electric dipole moment? B E hν = 2 (µb+d n E) hν = 2 (µb- d n E) h ν = 4 d n E 11

12 Standard Model EDM-expectations? Leptons: electroweak negligible Neutron, proton, nuclei: electroweak negligible, strong? 12

13 Standard model lepton EDMs Fourth order electroweak, F. Hoogeveen: The Standard Model Prediction for the Electric Dipole Moment of the Electron, Nucl. Phys. B 241 (1990) new physics? 13

14 Standard model lepton EDMs Fourth order electroweak, F. Hoogeveen: The Standard Model Prediction for the Electric Dipole Moment of the Electron, Nucl. Phys. B 241 (1990) 322 Completely negligible at any experimental sensitivity we can imagine today! + new physics? Much greater sensitivity to new, CP-violating physics! 14

15 Standard model lepton EDMs Fourth order electroweak, Completely negligible at any experimental sensitivity we can imagine today! F. Hoogeveen: The Standard Model Prediction for the Electric Dipole Moment of the Electron, Nucl. Phys. B 241 (1990) 322 Expect from SM, approximately: d e e cm d µ e cm d τ e cm Experimentally so far: d e < 1 x e cm d µ < 2 x e cm d τ < 3 x e cm + new physics? Much greater sensitivity to new, CP-violating physics! 15

16 Neutron: Standard Model prediction 16

17 Neutron: Standard Model prediction Completely negligible at any experimental sensitivity we can imagine today! Expect from electro-weak SM, approximately: d n e cm Experimentally so far: d n < 3 x e cm 17

18 The strong CP problem [e cm] QCD θ L QCD L QCD =0 QCD + g 2 /(32π 2 ~ ) θ QCD GG Smith, Purcell, Ramsey PR108(1957)120 d n e cm θ QCD θ QCD < ~ Why is θ QCD so small? EDM upper limit [e cm] RAL-Sussex-ILL d n < 2.9 x e cm C.A.Baker et al., PRL 97 (2006) here, e.g., d p = - d n and d D ~ 1/3 d n

19 The SUSY CP problem (for neutron and electron!) [e cm] d n e cm ( 300 GeV/c M SUSY 2 2 )sinφ SUSY Why is φ SUSY so small? (this is testing M already to 10TeV and you may also ask: why are the masses so huge?) EDM upper limit [e cm] SUSY Pospelov, Ritz, Ann. Phys. 318(2005)119 for M SUSY = 500GeV, tan β =

20 Origin of EDMs This is what we need µ neutron & proton EDMs Solid state EDM effects GdIG,GdYIG, (EU,Ba)TiO 3 EDMs of paramagnetic atoms & molecules Tl,Cs..,YbF,,ThO) PbO,ThO,HfF +,WC.. EDMs of diamagnetic atoms Hg, Xe, Ra, Rn.. Adapted from: Pospelov, Ritz, Ann. Phys. 318 (2005) 119 St. Petersburg FL, May 30, 2012 M. Raidal et al., Eur. Phys. J. C 57 (2008) 13 Klaus Kirch 20

21 Origin of EDMs This is what we need µ neutron & proton EDMs These we can access Solid state EDM effects GdIG,GdYIG, (EU,Ba)TiO 3 EDMs of paramagnetic atoms & molecules Tl,Cs..,YbF,,ThO) PbO,ThO,HfF +,WC.. EDMs of diamagnetic atoms Hg, Xe, Ra, Rn.. Adapted from: Pospelov, Ritz, Ann. Phys. 318 (2005) 119 St. Petersburg FL, May 30, 2012 M. Raidal et al., Eur. Phys. J. C 57 (2008) 13 Klaus Kirch 21

22 Origin of EDMs µ This is what we need CP-violating parameters: should be deduced neutron & proton EDMs These we can access Solid state EDM effects GdIG,GdYIG, (EU,Ba)TiO 3 EDMs of paramagnetic atoms & molecules Tl,Cs..,YbF,,ThO) PbO,ThO,HfF +,WC.. EDMs of diamagnetic atoms Hg, Xe, Ra, Rn.. Adapted from: Pospelov, Ritz, Ann. Phys. 318 (2005) 119 St. Petersburg FL, May 30, 2012 M. Raidal et al., Eur. Phys. J. C 57 (2008) 13 Klaus Kirch 22

23 Origin of EDMs... of mostly composite systems! Direct limits Active R&D µ Theory Solid state EDM effects GdIG,GdYIG, (EU,Ba)TiO 3 EDMs of paramagnetic atoms & molecules Tl,Cs,YbF,,ThO) Fr,PbO,ThO,HfF +,WC.. EDMs of diamagnetic atoms Hg, Xe, Ra, Rn.. neutron & proton EDMs Experiment Adapted from: Pospelov, Ritz, Ann. Phys. 318 (2005) 119 St. Petersburg FL, May 30, 2012 M. Raidal et al., Eur. Phys. J. C 57 (2008) 13 Klaus Kirch 23

24 gin of EDMs neutron & proton EDMs State of the art neutron d n < 2.9 x e cm PRL97(2006) Hg-199 d Hg < 3.1 x e cm PRL102(2009) d p < 8 x e cm* Xe-129 d Xe < 6 x e cm PRL86(2001)22 Tl-205 d Tl < 9 x e cm d e < 1.6 x e cm* PRL88(2002) YbF d e < 1.05 x e cm* Nature473(2011)493 muon d µ < 1.8 x e cm PRD80(2009) * using the 1-miracle assumption, i.e. no cancelations with other CP-odd effects. EDMs of diamagnetic atoms Hg, Xe, Ra, Rn.. Only for one fundamental fermion, the muon, a direct EDM-limits exist. Many people consider the neutron almost fundamental -- so we may perhaps count two direct basic EDM limits. 24

25 Complex composite systems have constituents and interactions Paramagnetic atoms Paramagnetic molecules enhancement additional enhancement from large internal electric fields of order 10 GV/cm or more, influenced by molecular level structure Diamagnetic atoms suppression of order 10 3 enhancement factors possible due to atomic state mixing and nuclear deformation. 25

26 Hg-199 EDM at Seattle The best EDM limit in absolute terms: d Hg < 3.1 x e cm (95% C.L.) Limiting various CP-violating parameters: 26

27 EDM landscape More than 30 efforts under way world-wide (plus many ideas...) Neutrons Ions+Muons Atoms Molecules Solids collaborations ranging from university groups of 2-3 or 10 to relatively large international collaborations 27

28 EDM @J-PARC 28

29 EDM @J-PARC Essentially all projects aim at sensitivities of a few x ecm within the next decade. Some promise intermediate results of a few x ecm within the next 3 years. 29

30 EDM 30

31 EDM Dedicated p and d storage ring experiments aiming at ecm. Proposals at BNL and FZJ. JEDI at FZJ aims at d d ~10-24 ecm. Muon EDM can be improved to better than e cm at the planned new g-2 experiments within the next decade. Dedicated muon EDM experiments at PSI (5x10-23 ecm) and J-PARC (10-24 ecm) presently not pushed further. Variants of frozen spin technique PRL93(2004)

32 EDM landscape Atoms

33 EDM landscape Atoms Hg-199 EDM plans to improve to few x ecm by Xe-129 efforts aim at ecm as a first/next step. Cs exps. aim at few x ecm for d e around Fr aims at few x ecm for d e after Ra at KVI aims at ecm (and ecm for d e ) 33

34 EDM landscape Molecules 34

35 EDM landscape Molecules YbF works on improvement by factor 3 in x10-28 ecm and aims at sensitivity for de of 4x10-29 ecm by ThO presently taking data, to either soon discover the electron edm or to significantly reduce the current limit. HfF+ and WC aiming at ecm in a few years. 35

36 EDM landscape Solids 36

37 EDM landscape Solids Gadolinium Gallium Garnet aims at ecm for d e in Estimated reach (S. Lamoreaux, PRA2002) ~10-30 ecm. Studies on various ferro-electric substances. 37

38 @JPARC ~50 Molecules ~10 Solids Rough estimate of numbers of researchers, in total ~500 (with some overlap) ~100 Atoms

39 Technology & Fields particle and neutron sources atom and molecular beam sources radioactive ion beams exotic molecules laser, trapping high voltage magnetometry & shields magnetic field control new materials... Experiment&Theory of: particle physics neutron physics atomic physics nuclear physics molecular physics accelerator and beam physics solid state physics surface science chemistry... 39

40 Technology & Fields particle and neutron sources atom and molecular beam sources radioactive ion beams exotic molecules laser, trapping high voltage magnetometry & shields magnetic field control new materials... Major common issues (for different subsets): - statistics and (cold) sources - magnetic field homogeneity, gradients and stability - state preparation and spin coherence times - control of HV, noise, reversal, leakage currents - stability of lasers, trapping, pumping - motional fields, geometric phases,... Experiment&Theory of: particle physics neutron physics atomic physics nuclear physics molecular physics accelerator and beam physics solid state physics surface science chemistry... 40

41 courtesy: Koichiro Asahi Setup for the spin oscillator experiment Si photodiode Bandwidth : khz magnetic shield (4-layer) permalloy B 0 Solenoid coil (static field) B 0 = 30.6 mg (I = ma) λ/4 plate Heater T 70 C spin precession signal 129 Xe gas cell 18 mm 129 Xe : 230 torr N 2 : 100 torr Rb : ~ 1 mg Pyrex glass SurfaSil coating PEM Probe laser DFB laser λ = nm (Rb D1line) λ = nm Power : 15 mw Pumping laser λ = nm (Rb D1line) λ = 3 nm Power ~ 11 W 41

42 YbF: d e <1.05 x e cm Nature 473(2011)10104 YbF-EDM@Imperial courtesy: Ben Sauer 42

43 courtesy: Huanqian Loh, Eric Cornell 43

44 Laser cooling leaky systems: Barium 1 P 1 3 D 1 Multiple repump transitions Efficient capture from atomic beam (>1%) λ 1 1 D 2 3 D 123 Radium similar level scheme. Laser cooling approach transferable 1 S 0 Ra-EDM@KVI courtesy: Lorenz Willmann Rate [10 6 /s] MOT signal Doppler-free beam signal X λ 1 [MHz] S. De et al., Phys. Rev. A 79, (R) (2009) 44

45 Search for the electron-edm with cold Cs and Rb atoms in optical lattices Kunyan Zhu, Neal Solmeyer, Cheng Tang and David Weiss NSF E courtesy: David Weiss Simultaneously measure with two opposite E-fields and minimal bias B-field. Use in situ measurements of 5 to 10 cm long linear arrays of atoms to cancel magnetic field gradients and monitor potential systematic errors. The atomic physics can be unraveled from a measurement with ~1% accuracy. E Rbatoms provide an ultimate check on any Cs result. We expect >200x improved sensitivity. 45

46 courtesy: Yasuhiro Sakemi 46

47 Labs to host S.R. EDM experiments BNL, USA: proton magic ring COSY, Jülich/Germany deuteron ring: JEDI courtesy: Yannis Semertzidis, Frank Rathmann 47

48 Two storage ring projects being pursued BNL for protons all electric machine Jülich, focus on deuterons, or a combined machine CW and CCW propagating beams (from R. Talman) (from A. Lehrach) 48 48

49 courtesy: Anatoli Serebrov 49

50 Japan-Canada nedm experiment Spherical coil for DC field Xe-129 nuclear-spin buffer-gas comagnetometer Room-temp experiment, keeping EDM cell size small, anticipating gains in UCN density Modern magnetic shielding, cost reduced with cell size Superfluid He-4 UCN source Basic prototype in operation courtesy: Yasuhiro Masuda, Jeff Martin 50

51 Sussex et courtesy: Philipp Harris 51

52 Neutron SNS Aiming at sensitivity of 3 x e cm, construction ends 2018 courtesy: Brad Filippone 52

53 Installing nedm at PSI in 2009 nedm.web.psi.ch Coming from ILL Sussex-RAL-ILL collaboration PRL 97 (2006)

54 nedm.web.psi.ch 54