The Search for Axions Pierre Sikivie Axion Dark Matter Conference & Oscar Klein Centre Colloquium December 5, 2016

Outline Axion motivation and properties Production in the early universe Axion dark matter detection Other methods

The Strong CP Problem where The absence of P and CP violation in the strong interactions requires from upper limit on the neutron electric dipole moment

A level pooltable on an inclined floor g

The Standard Model does not provide a reason for to be so tiny, but a relatively small modification does …

is a symmetry of the classical action is spontaneously broken has a color anomaly Peccei and Quinn, 1977

If a symmetry is assumed, relaxes to zero, and a light neutral pseudoscalar particle is predicted: the axion. Weinberg, Wilczek 1978

A self adjusting pooltable 1 ton

f f a a = 0.97 in KSVZ model 0.36 in DFSZ model

Searching for the pooltable oscillation quantum 1 ton

Axions are constrained by beam dump experiments rare particle decays radiative corrections the evolution of stars

from G. Raffelt, 0611350

The remaining axion window laboratory searches cosmology stellar evolution

Thermal axions g a q these processes imply an axion decoupling temperature thermal axion temperature today: = effective number of thermal degrees of freedom at axion decoupling

There are two cosmic axion populations: hot and cold. When the axion mass turns on, at QCD time,

Effective potential V(T, ) axion strings axion domain walls

Axion production by vacuum realignment initial misalignment angle J. Preskill, M. Wise & F. Wilczek, L. Abbott & PS, M. Dine & W. Fischler, 1983

A self adjusting pooltable 1 ton

If inflation after the PQ phase transition . may be accidentally suppressed . produces isocurvature density perturbations CMBR constraint

If no inflation after the PQ phase transition . cold axions are produced by vacuum realignment, string decay and wall decay . S. Borsanyi et al. 1606.07494 axion miniclusters appear

Axions are cold dark matter Density Velocity dispersion Effective temperature

Searching for relic pooltable oscillations 1 ton

Axion Search Techniques the cavity haloscope the axion helioscope shining light through walls axion mediated long-range forces NMR methods LC circuit atomic transitions

Axion dark matter is detectable PS '83 a X A/D FFT

conversion power on resonance search rate for s/n = 4

Axion Dark Matter eXperiment

ADMX hardware high Q cavity experimental insert

ADMX in its second generation *Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, NSF Grant PHY-1067242, and the Livermore LDRD program

Upgrade with SQUID Amplifiers IB The basic SQUID amplifier is a flux-to-voltage transducer SQUID noise arises from Nyquist noise in shunt resistance scales linearly with T However, SQUIDs of conventional design are poor amplifiers above 100 MHz (parasitic couplings). F Vo (t) Flux-bias to here

Quantum-limited SQUID-based amplification SQUIDs have been measured with TN ~ 50 mK Compared to ~ 2 K for HFET amplifiers Near quantum– limited noise Provides a large increase in ADMX sensitivity SQUID amplifiers J. Clarke et al.

Will scan the lower-mass decade at or below DFSZ sensitivity Gen 2 ADMX sensitivity Will scan the lower-mass decade at or below DFSZ sensitivity

ADMX-HF at Yale Multi-post system that consists of 3 rotors connected on common axis and 3 stators. 4” ID cavity: Six 0.5” diameter rods Freq. span 4.7- 6.0 GHz

B. Brubaker et al., arXiv: 1610.02580

Center for Axion and Precision Physics (CAPP) in Korea

Axion Search Techniques the cavity haloscope the axion helioscope shining light through walls axion mediated long-range forces NMR methods LC circuit atomic transitions

Axion to photon conversion in a magnetic field Theory P. S. ’83 L. Maiani, R. Petronzio and E. Zavattini ’86 K. van Bibber et al. ’87 G. Raffelt and L. Stodolsky, ‘88 K. van Bibber et al. ’89 Experiment D. Lazarus et al. ’92 R. Cameron et al. ‘93 S. Moriyama et al. ’98, Y. Inoue et al. ’02 K. Zioutas et al. 04 E. Zavattini et al. 05 x conversion probability with

Tokyo Axion Helioscope

Cern Axion Solar Telescope Decommissioned LCH test magnet Rotating platform 3 X-ray detectors X-ray Focusing Device Sunset Photon detectors Sunset axions Sunrise axions Sunrise

CAST Collaboration: Phys. Rev. Lett. 112 (2013) 091302

Primakoff conversion of solar axions in crystals on Earth Solax, Cosme ’98 a Ge DAMA ‘01 x NaI (100 kg) CDMS ‘09 few keV Ge Bragg scattering on crystal lattice Edelweiss ‘13 Ge

from C. Eleftheriadis (CAST), arXiv: 0706.0637

Axio-Electric Effect Theory Experiment F. Avignone et al., '87 S. Dimopoulos, G.D. Starkman & B.W. Lynn, '86 F. Avignone et al., '87 E. Aprile et al., '09 E. Armengaud et al. ‘13

Linearly polarized light in a constant magnetic field

Rotation

Rotation and Ellipticity Maiani, Petronzio and Zavattini, 1986

PVLAS

Shining light through walls K. van Bibber et al. ‘87 A. Ringwald ‘03 R. Rabadan, A. Ringwald and C. Sigurdson ‘05 P. Pugnat et al. '05 C. Robilliard et al. '07 A. Afanasev et al. '08 A. Chou et al. '08 K. Ehret et al. '10 a x x rate

Limits from "light through wall" axion searches

Resonantly Enhanced Axion-Photon Regeneration Wall Photon Detector a  Laser L B0 Magnet Matched Fabry-Perots IO Laser Magnet Photon Detectors (b) Hoogeveen (1996); P.S., Tanner and van Bibber (2007) & G. Mueller (2009)

Macroscopic forces mediated by axions Theory: J. Moody and F. Wilczek ’84 Experiment: A. Youdin et al. ’96 W.-T. Ni et al. ‘96 forces coupled to the f spin density forces coupled to the f number density background of magnetic forces

NMR with long range axion field A. Arvanitaki and A. Geraci, 2014 th the rotating mass on the left produces an oscillating axion field the oscillating axion field is an effective magnetic field in an NMR experiment

Axion Search Techniques the cavity haloscope solar axion searches shining light through walls NMR methods axion mediated long-range forces LC circuit atomic transitions

NMR techniques P. Graham, S. Rajendran; D. Budker, M. Ledbetter, A. Sushkov

the axion field induces an oscillating nuclear electric dipole moment

Axion dark matter detection using an LC circuit PS, D. Tanner and N. Sullivan, 2013 to re circuit should be cooled to milli-Kelvin temperatures

Wire array detector - pass currents through superconducting wires PS, D. Tanner and Y. Wang, 1992 G. Rybka, A. Wagner et al. 2004 - pass currents through superconducting wires - produce - enhance the quality factor by placing the array in a confocal resonator - tune to

Dielectric Haloscope A. Caldwell et al., arXiv 1611.05865

Dish antenna D. Homs, J. Jaeckel, A. Lindner, A. Lobanov, J. Redondo & A. Ringwald, 2013 B. Doebrich et al. ,2014

Axion dark matter detection using atomic transitions PS 2014 - tune using the Zeeman effect - use laser techniques to count axion induced transitions - must cool to milli-Kelvin temperatures

Conclusions Axions solve the strong CP problem A population of cold axions is naturally produced in the early universe which may be the dark matter today Axion dark matter is detectable