Electric Dipole Moments: Searches at Storage Rings September 2017 | Hans Ströher (Forschungszentrum Jülich)

New physics: empirical evidence (n-oscillations, dark matter, baryon asymmetry) doesn´t a priori point to a specific mass scale Direct searches („energy frontier“) Indirect searches („precision frontier“) Precision observables that vanish (or are suppressed) by symmetry in the SM allow for new physics searches with indirect reach in both Energy scale Strength of coupling Example: new CP-odd sources  EDMs Required for baryogenesis (Sakharov conditions) Strong CP problem (suppression of q QCD) 2

Permanent Electric Dipole Moments (EDM) of non- degenerate fundamental systems (particles): A vector (d), connecting the centroids of positive and negative charge distributions, in the direction of the spin vector (µ). 3

Permanent Electric Dipole Moments (EDM) of non- degenerate fundamental systems (particles): violate P- and T-, and (via CPT) also CP-symmetry 4

Permanent Electric Dipole Moments (EDM) of non- degenerate fundamental systems (particles): F. Wilczek, Jan. 2014 5

Multiple experimental input is required to disentangle the fundamental source(s) of EDMs: Jordy de Vries, 2012 6

A huge ongoing experimental effort … Multiple experimental input is required to disentangle the fundamental source(s) of EDMs: A huge ongoing experimental effort … 7

Experimental status of EDMs: best limits for bare nucleon (n, p), lepton (e, m), diamagnetic atom (199Hg), paramagnetic atom (205Tl) and molecules (YbF, ThO): Aim: few times 10-28 ecm Direct measurements:  srEDM ThO |de| < 8.7 x 10-29 ecm 90% C.L. factor 10 in next 10 yrs P. Harris, K. Kirch, July 2012 8

Charged particle (p, d) EDMs - principle of experiment: Inject polarized particles into a storage ring Apply radial electric field E: Non-zero EDM  spin rotation out of the plane

Charged particle (p, d) EDMs - principal challenges: Spin motion („Thomas-BMT equation“)  effect due to magnetic moment Way out: (i) B = 0 („all-electric ring“) (ii) „magic momentum“, i.e.: (only for G > 0, proton) „frozen spin“ method (NB: for deuteron: combined E-B fields)

+ - Charged particle (p, d) EDMs - principal challenges EDMs are very (!) small:  systematics, fake EDM effects + <10 µm - Neutron 1 fm 1022 fm

Charged particle (p, d) EDMs: technological challenges Current solution:  dedicated precision storage ring with two beams (CW, CCW)  goal: sensitivity of 10-29 e cm (stepwise approach: R&D, precursor, srEDM-ring) pEDM: (all-electric) one ring dEDM: (combined E-B) two separate rings

Charged particle (p, d) EDMs – Step-1: key technologies Spin tune measurement: Measurement at COSY: 970 MeV/c: ns = 120 kHz u/d asymmetry dC scattering precision ~ 10-8 (Dt = 2.6 s) precision ~ 10-10 (Dt = 100 s) “COSY-Jülich” PRL 115, 094801 (2015) PR STAB 20, 072801 (2017)

Charged particle (p, d) EDMs – Step-1: key technologies Spin coherence time (SCT): Optimization of SCT at COSY: Beam bunching Electron cooling Sextupole field corrections Limit in beam current SCT ~ 1000s “COSY-Jülich” PRL 117, 054801 (2016) CERN Courier, Aug. 2016

Charged particle (p, d) EDMs – Step-1: key technologies Phase locking of spin precession:  Prerequisite for precursor experiment … Control/feedback at COSY: 970 MeV/c: ns = 120 kHz Real-time synchronisation w/ an RF-solenoid - Control of phase s = 0.21 rad “COSY-Jülich” PRL 119, 014801 (2017)

Charged particle (p, d) EDMs – Step 2: dEDM at COSY Precursor experiment  (w/ „RF Wien-filter“): 1st commissioning done 1st measurement in 2018 sensitivity 10-24 e.cm (stat.) NIM A 828 (2016) 116 AdG „srEDM“, No.694390 www.sredm-ercgrant.de

Charged particle (p, d) EDMs – Step 3: final ring design CDR (or TDR) of CPEDM-ring: Design parameters (p): Momentum: 0.701 GeV/c Energy: 1.171 GeV Circumference: ~ 500 m Bending sections: ~ 10 m Straight sections: ~ 21 m E-Field: 8 MV/m

Charged particle (p, d) EDMs – Summary: Science case (CP-V) New option srEDM Stepwise approach  JEDI at COSY: PBC at CERN

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