Seminar KVI, 1 July 2004 EDMs in Storage Rings: Powerful Probes of Physics Beyond the SM and of CP-Violation Yannis K. Semertzidis Brookhaven National Laboratory • EDMs: Why are they important? • Our Universe: The Symmetry that isn’t • EDM Experimental Techniques • EDMs in Storage Rings • Prospects of the Field
+ - + - Phenom.: only the component along the spin survives... Spin is the only vector…
+ T - + - P - + A Permanent EDM Violates both T & P Symmetries:
T P A Permanent EDM Violates both T & P Symmetries:
T OK P OK 1st order Stark effect. Forbidden! 2nd order Stark effect. Allowed! Reality Check: Induced EDMs…
T P Reality Check: MDMs are Allowed…
CPT T-Violation CP-Violation Andrei Sakharov 1967: CP-Violation is one of three conditions to enable a universe containing initially equal amounts of matter and antimatter to evolve into a matter-dominated universe, which we see today….
Flashback Before 1929: • Universe is Static-Eternal • Cosmological Constant is Invented to Stabilize it! • Dirac Equation 1928: • g=2 for Point-like, Spin ½ Particles • Negative Energy States
Hubble 1929: • Universe is Expanding • …If the Universe Expands… a Beginning and a BIG BANG! • Km/MPa/s or 10-18s-1 • Discovery of Positron by Anderson: 1933
At Accelerators: • 1955: Antiproton Discovery at Berkeley • 1956: Antineutron Discovery • 1957: Parity Violation, Lee-Yang • 1964: CP-Violation at Brookhaven • Universe: Matter Dominated; Initial Condition Maintained by B, L Number Conservation.
Andrei Sakharov 1967: • Three conditions to enable a universe containing initially equal amounts of matter and antimatter to evolve into a matter-dominated universe, which we see today: • Proton Decay (Baryon Number Violation) • CP-Violation • Universe Undergoes A Phase of Extremely Rapid Expansion
Extension of the SM Needed? • SM: CP-Violation not Enough by Several Orders of Magnitude for Baryogenesis • Leptogenesis: CP-Violation in Neutrino Mixing? • Heavy, Weakly Interacting, Right-Handed Neutrinos Produced in Early Universe • Their Decays Produces Lepton Number Asymmetry. • Further Interactions Conserving B-L Convert it to Baryon Number Asymmetry
EDM Searches are Excellent Probes of Physics Beyond the SM: SM: One CP-Violating Phase (CKM), Needs loops with all quark families for a non-zero result (Third Order Effect). 42 CP-Violating Phases, Needs one loop for a non-zero result (First Order Effect). SUSY:
ála Fortson d ~
Carrier Signal E Small Signal + Compare the Zeeman Frequencies When E-field is Flipped: - Usual Experimental Method
Schiff Theorem:A Charged Particle at Equilibrium Feels no Force……An Electron in a Neutral Atom Feels no Force Either: …Otherwise it Would be Accelerated…
S. Lamoreaux at “Lepton Moments”, June 2003 E=5MV/m, T=108s R&D
Cost of the n-EDM Experiment at LANSCE • $10M for the experimental apparatus • $9M for the Beamline • R&D? • Total $19M plus R&D
Schiff Theorem:A Charged Particle at Equilibrium Feels no Force……An Electron in a Neutral Atom Feels no Force Either. However: …the net E-field is not zero!
Electron EDM 10-20 Cs 10-22 Cs 10-24 Xe* Hg Experimental Limit on de (e .cm) Cs 10-26 Tl Tl Tl ?? 10-28 10-30 1960 1970 1980 1990 2000 2010
Current Atomic EDM Limits • Paramagnetic Atoms, 205Tl: electron |de| < 1.610-27e·cm (90%CL) PRL 88, 071805 (2002) • Diamagnetic Atoms, 199Hg Nucleus: |d(199Hg)| < 2.110-28e·cm (95%CL) PRL 86, 2505 (2001)
Electric Dipole Moments in Storage Rings e.g. 1T corresponds to 300 MV/m!
Spin Precession in g-2 Ring(Top View) Momentum vector m Spin vector Angle: a / turn
Energy Spectrum of Detected Positrons Momentum vector Spin vector Momentum vector Spin vector Software Energy Threshold
Indirect Muon EDM limit from the g-2 Experiment z y s β x B Ron McNabb’s Thesis 2003:
Canceling g-2 with a Radial E-field z B E y s β x
Radial E-field to Cancel/Control the g-2 Precession • Radial E-Field: The method works well for particles with small anomalous magnetic moment a, e.g. Muons (a = 0.0011), Deuterons (a = -0.143), etc.
Effect of E-Field to g-2 Precession In a B-Field In an E-Field
Momentum vector Spin vector Spin Precession in g-2 Ring(Top View) m
Momentum vector Spin vector Spin Precession in EDM Ring(Top View) m
(U-D)/(U+D) vs Time (U-D)/(U+D)
Statistical Error (Muon Case): : 11s. Muon Lifetime A : 0.3 Vertical Asymmetry NTot P2: 51016 The beam intensity at J-PARC per year. ER : 2MV/m Radial electric field value per year
Two Major Ideas: • Radial E-field to Cancel the g-2 Precession • Injecting CW and CCW • Sensitivity: 10-24 e·cm statistical (1 yr, 0.75MW) • Sensitivity: 10-27 e·cm systematic error • Muon EDM LOI: (http://www.bnl.gov/edm) to J-PARC.
Muon EDM Letter of Intent to J-PARC/Japan, 2003 † † # • †Spokesperson • # Resident Spokesperson
Predictions in Specific Models 50 effect at 10-24 ecm Exp. Sensitivity! The predicted value for the electron is 10 times less than the current experimental limit.
g-2 Values • Electron 0.0016 done • Muon 0.0017 doing • Proton 1.8 ------ • Deuteron -0.143 OK!
Deuteron Coherence Time • E, B field stability • Multipoles of E, B fields • Vertical (Pitch) and Horizontal Oscillations • Finite Momentum Acceptance ΔP/P At this time we believe we can do p>10s
Nuclear Scattering as Deuteron EDM polarimeter • IDEA: • make thick target defining aperture • scatter into it with thin target detector system U “defining aperture” primary target L “extraction” target - ribbon R D R Δ D Target could be Ar gas (higher Z). Detector is far enough away that doughnut illumination is not an acceptance issue: Δ < R. Hole is large compared to beam. Every- thing that goes through hole stays in the ring. Target “extracts” by Coulomb scattering deuterons onto thick main target. There’s not enough good events here to warrant detectors.
Deuteron Statistical Error (200MeV): p : 10s. Polarization Lifetime (Coherence Time) A : 0.5 The left/right asymmetry observed by the polarimeter P : 0.55. The beam polarization Nc: 41011d/cycle. The total number of stored particles per cycle TTot: 107s. Total running time per year f : 0.01 Useful event rate fraction ER : 3.5MV/m. Radial electric field per year