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Search for the Electron Electric Dipole Moment Val Prasad Yale University Experiment: D.DeMille, D. Kawall, R.Paolino, V. Prasad F. Bay, S. Bickman, P.Hamilton, Y. Jiang, Y.Gurevich Yale University L.R.Hunter (Amherst) Theory: M. Kozlov (PNPI, St. Petersburg), D. DeMille
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An EDM Violates Parity and Time Reversal Symmetries and may provide evidence of new physics T-violation: a window to new physics P T D S look different after P reversal look different after T reversal CPT theorem T-violation = CP-violation
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Feynman Diagram ee not renormalizable loop diagrams
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Std Model: Standard Model LR-S: Left-Right Symmetric L-FC: Lepton flavor-changing M-H: Multi-Higgs TC: Technicolor AC: Accidental Cancellations HsF: Heavy sFermions A-CP: Approx. CP A-Un: Approx Universality Align: Alignment E-Un: Exact Universality M-H NAIVE SUSY AC A-CP A-Un Align HsF SO(10) GUT LR-S L-FC TC 10 -26 10 -28 10 -30 d e (e·cm) Berkeley Yale I (projected) 10 -32 E-Un 10 -40 Std Model Experimental limit: |d e | < 1.610 -27 ecm (Berkeley) Yale II (projected) Theoretical Predictions for d e
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General Method to Detect an EDM spin E B Energy Shift Resolution ~ ____(d e.E eff )_______ (T coh.√(dN/dt T meas )) -1
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Schiff’s theorem Near nucleus, v, E, large + substantial amplitude for valence e-: r ~ a 0 /Z; v ~ Z c; E ~ Ze/r 2 ; B ~ ea 0 ; (0) ~Z 1/2 | | Z 3 2 (e/a 0 2 ) P Cannot apply an electric field to a free electron for long times Use a neutral object (atoms, molecules)
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Molecules enhance electric fields Atoms Large laboratory fields ~50 kV/cm Leakage currents=BAD!!! Smaller enhancement factors Pb O E E ext ~10 V/cm E int ~10 10 V/cm Molecules Unpaired electron=free radical Boltzmann distribution over many rovibrational states M. G. Kozlov and D. DeMille Phys. Rev. Lett. 89, 133001 (2002)
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An aside: what’s an -doublet? Symmetric-antisymmmetric states split by tunneling =0 =-1 =+1 = 1 states coupled in 2 nd order via molecular rotation (Coriolis) E ~ ( E rot ) 2 / E st ~ 10 -3 E rot Non-rotating molecule has internal tensor Stark shift
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Thallium vs PbO* Atom/MoleculeThalliumPbO* GroupBerkeley Yale/ Amherst Applied field (V/cm)10 5 >15 Effective field (V/cm) 6 10 7 3-6 10 10 !! Coherence time T (ms)30.1 Count rate (1/s) 2 10 9 10 11 Figure of merit1240 Projected sensitivity (e cm)2 10 -28 10 -29 /10 -31 Present limit (e cm)<1.6 10 -27 ??? PbO*: ΔE edm = 2.5 x 10 25 Hz x d e (e-cm)
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Excitation scheme 0+0+ 1-1- 2+2+ X(0)[ 1 Σ + ] 1-1+1-1+ 2+2-2+2- a(1) [ 3 Σ+] ~10 GHz ~12 MHz Laser pulse λ~571 nm t~10 ns Bandwidth~1GHz~Δ ν Doppler R 0 208 Pb J’’= 0→J’=1
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Molecular Spectra R0(J”=0 J’=1 - ) 208 Pb X(v’’ = 1) a(v’ = 5) excitation ( = 571 nm) a(v’ = 5) X(v’’ = 0) detection ( = 548 nm) Integrated over ~200 s after each pulse Tune laser here Integrated intensity
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Omega Doublet m=-1 m=0 m=1 B =0 E ν Zeeman ~300 kHz ν ~11.2 MHz
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Excitation Scheme B E RF pulse
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Excitation Scheme B E RF pulse
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Excitation Scheme B E RF pulse
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Quantum Beats Coherent superposition of two states decaying to the same state Precession frequency proportional to energy difference between states Allows for Doppler free, very precise spectroscopy (<1mHz) x y
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Systematics Considerations Motional Magnetic Fields Magnetic Noise Leakage Currents Multi-photon ionization E-field gradients Inhomogeneities in E-field Stray B-fields and E-fields
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g-factor measurement Results help constrain calculation of enhancement-factor -doublet useful as Co-Magnetometer To what extent is the - doublet a perfect mirror image?
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Typical Data Averaged over 0.5 s, B z ~60 mG
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Rabi Flopping
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Stark Shift = Zeeman Shift
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Omega Doublet m=-1 m=0 m=1 B =0 E ν Zeeman ~300 kHz ν ~11.2 MHz
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Conclusions Many preliminary steps have been successfully demonstrated Improvements in excitation and detection efficiencies look promising Attacking a few remaining experimental issues before we take a first look at the data …………….
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