georg raffelt, mpi physics, munich 4 th schrödinger lecture, university vienna, 24 may 2011 axions...

Georg Raffelt, MPI Physics, Munich 4th Schrödinger Lecture, University Vienna, 24 May 2011

AxionsGeorg G. Raffelt, Max-Planck-Institut für Physik, MünchenGeorg G. Raffelt, Max-Planck-Institut für Physik, München

AxionsAxionsMotivation, Cosmological Roleand Astrophysical LimitsMotivation, Cosmological Roleand Astrophysical Limits

4th Schrödinger Lecture, Universität Wien, 24 May 20114th Schrödinger Lecture, Universität Wien, 24 May 2011


CP Violation in Particle Physics

Physics Nobel Prize 2008

Discrete symmetries in particle physicsC – Charge conjugation, transforms particles to antiparticles violated by weak interactionsP – Parity, changes left-handedness to right-handedness violated by weak interactionsT – Time reversal, changes direction of motion (forward to backward)CPT – exactly conserved in quantum field theoryCP – conserved by all gauge interactions violated by three-flavor quark mixing matrix

M. Kobayashi T. Maskawa

All measured CP-violating effects derive from a single phase in the quark mass matrix (Kobayashi-Maskawa phase), i.e. from complex Yukawa couplings Cosmic matter-antimatter asymmetry requires new ingredients


Measurements of CKM Unitarity Triangle

CKMfitter Grouphttp://ckmfitter.in2p3.fr

UTfit Collaborationhttp://www.utfit.org


Kobayashi and Maskawa


The CP Problem of Strong Interactions

ℒQCD=∑𝑞

𝜓𝑞( i𝐷−𝑚𝑞𝑒i 𝜃𝑞 )𝜓𝑞−

14𝐺𝜇𝜈𝑎𝐺𝑎

𝜇𝜈−Θ𝛼 s8𝜋

𝐺𝜇𝜈 𝑎

~𝐺𝑎𝜇𝜈

𝜓𝑞→𝑒❑−𝑖𝛾 5𝜃𝑞 /2𝜓𝑞

ℒQCD=∑𝑞

𝜓𝑞 (i𝐷−𝑚𝑞)𝜓𝑞−14𝐺𝐺− (Θ− arg det𝑀𝑞)⏟

−𝜋 ≤Θ≤+𝜋

𝛼s8𝜋

𝐺~𝐺

Real quarkmass

Phase fromYukawa coupling

Anglevariable

CP-oddquantity

Remove phase of mass term by chiral transformation of quark fields

can be traded between quark phases and term No physical impact if at least one Induces a large neutron electric dipole moment (a T-violating quantity)

Experimental limits: Why so small?


Neutron Electric Dipole Moment

Violates time reversal (T) andspace reflection (P) symmetries

Natural scale𝑒

2𝑚𝑁

=1.06×10−14𝑒cm

Experimental limit|𝑑|=0.63×10− 25𝑒 cm

Limit on coefficient

Θ𝑚𝑞

𝑚𝑁

≲10−11


Dynamical SolutionPeccei & Quinn 1977, Wilczek 1978, Weinberg 1978

• Re-interpret as a dynamical variable (scalar field)

is pseudoscalar axion field, axion decay constant (Peccei-Quinn scale)

ℒCP=−𝛼 s8𝜋

ΘTr (𝐺~𝐺 )→−𝛼 s8𝜋

𝑎(𝑥)𝑓 𝑎

Tr (𝐺~𝐺 )

• Axions generically couple to two gluons and mix with, , , mesons, inducing a mass (potential) for

𝑚𝑎 𝑓 𝑎=√𝑚𝑢𝑚𝑑

𝑚𝑢+𝑚𝑑

𝑚𝜋 𝑓 𝜋 (A xion mass& couplings )∼( Pion mass

& couplings)×𝑓 𝜋𝑓 𝑎

𝑎

𝑉 (𝑎)

Θ=0

• Potential (mass term) induced by drives to CP-conserving minimum

CP-symmetry dynamicallyrestored


The Pool Table Analogy (Pierre Sikivie 1996)

GravitySymmetricrelativeto gravity

Pool table

New degree of freedom Axion

𝚯

(Weinberg 1978, Wilczek 1978)

Axis

Symmetrydynamicallyrestored

(Peccei & Quinn 1977)

Symmetrybroken

Floor inclined

fa


33 Years of Axions


The Cleansing Axion

Frank Wilczek

“I named them after a laundry detergent, since they clean up

a problem with an axial current.” (Nobel lecture 2004)


Axion Bounds

Directsearches

Too muchcold dark matter (classic)

TelescopeExperiments

Globular clusters(a-g-coupling)

Too manyevents

Too muchenergy loss

SN 1987A (a-N-coupling)

Too muchhot dark matter

CAST ADMXCARRACK

Classicregion

Anthropicregion

103 106 109 1012 [GeV] fa

eVkeV meV meVma

neV

1015


Supernova 1987A Energy-Loss Argument

SN 1987A neutrino signal Neutrinosphere

Neutrino

diffusion

Volume emission of novel particles

Late-time signal most sensitive observable

Emission of very weakly interactingparticles would “steal” energy from theneutrino burst and shorten it.(Early neutrino burst powered by accretion, not sensitive to volume energy loss.)


Diffuse Supernova Axion Background (DSAB)

Raffelt, Redondo & Viauxwork in progress (2011)

• Neutrinos from all core-collapse SNe comparable to photons from all stars• Diffuse Supernova Neutrino Background (DSNB) similar energy density as extra-galactic background light (EBL), approx 10% of CMB energy density • DSNB probably next astro neutrinos to be measured

• Axions with near SN 1987A energy-loss limit• Provide DSAB with compable energy density as DSNB and EBL• No obvious detection channel


Do White Dwarfs Need Axion Cooling?

Isern, Catalán, García-Berro & TorresarXiv:0812.3043

White dwarf luminosity function(number of WDs per brightness interval)No axions

With axion cooling( near SN1987A limit)


Axion as a Nambu-Goldstone Boson

• New U(1) symmetry, spontaneously broken at a large scale • Axion is “phase” of new Higgs field: angular variable • By construction couples to term with strength , e.g. triangle loop with new heavy quark (KSVZ model)• Mixes with -- mesons• Axion mass (vanishes if or )

𝑚𝑎=√𝑚𝑢𝑚𝑑

𝑚𝑢+𝑚𝑑

𝑚𝜋

𝑓 𝜋 𝑓 𝑎

ℒCP=𝛼𝑠8𝜋

Θ𝐺𝑎~𝐺𝑎→

α s8π (Θ− 𝑎(𝑥)𝑓 𝑎 )⏟

𝐺𝑎~𝐺𝑎

Periodic variable (angle)

Φ=𝑓 𝑎+𝜌 (𝑥 )

√2𝑒𝑖𝑎 (𝑥 )𝑓 𝑎


Creation of Cosmological Axions

(very early universe)

• UPQ(1) spontaneously broken• Higgs field settles in “Mexican hat”• Axion field sits fixed at

𝑎

𝑉 (𝑎)

𝑎

𝑉 (𝑎)

Θ=0

( eV)

• Axion mass turns on quickly by thermal instanton gas• Field starts oscillating when • Classical field oscillations (axions at rest)

Axions are born as nonrelativistic, classical field oscillationsVery small mass, yet cold dark matter


Axion Cosmology in PLB 120 (1983)


Killing Two Birds With One Stone

Peccei-Quinn mechanism• Solves strong CP problem• May provide dark matter in the form of axions


Cosmic Axion DensityModern values for QCD parameters and temperature-dependent axion massimply (Bae, Huh & Kim, arXiv:0806.0497)

If axions provide the cold dark matter:

• implies GeV and meV (“classic window”)

• GeV (GUT scale) or larger (string inspired) requires (“anthropic window”)

Ω𝑎h2=0.195Θi

2( 𝑓 𝑎1012GeV )

1.184

=0.105Θi2( 10𝜇eV𝑚𝑎

)1.184

Θi=0.75( 1012GeV𝑓 𝑎 )

0.592

=1.0 ( 𝑚𝑎

10𝜇eV )0.592


Cold Axion PopulationsCase 2:Reheating restores PQ symmetry

• Cosmic strings of broken UPQ(1) form by Kibble mechanism• Radiate long-wavelength axions• independent of initial conditions• or else domain wall problem

Inhomogeneities of axion field large,self-couplings lead to formation of mini-clustersTypical properties• Mass • Radius cm• Mass fraction up to several 10%

Case 1:Inflation after PQ symmetry breaking

Homogeneous mode oscillates after Dependence on initial misalignmentangle

• Isocurvature fluctuations from large quantum fluctuations of massless axion field created during inflation• Strong CMB bounds on isocurvature fluctuations• Scale of inflation required to be small

Dark matter density a cosmic randomnumber (“environmental parameter”)


Inflation, Axions, and Anthropic SelectionIf PQ symmetry is not restored after inflation• Axion density determined by initial random number • Different in different patches of the universe• Our visible universe, after inflation, from a single patch• Axion/photon ratio a cosmic random number, chosen by spontaneous symmetry breaking process

Allows for small and thus for at the GUT or string scale• Is this “unlikely” or “unnatural” or “fine tuned”?• Should one design experiments for very small-mass axion dark matter?

Difficult to form baryonic structures if baryon/dark matter density is too low,

posterior probability for small not necessarily small

• Linde, “Inflation and axion cosmology,” PLB 201:437, 1988• Tegmark, Aguirre, Rees & Wilczek, “Dimensionless constants, cosmology and other dark matters,” PRD 73:023505, 2006 [astro-ph/0511774]


Lee-Weinberg Curve for Neutrinos and Axions

log (Ω𝑎)

log (𝑚𝑎)

Ω𝑀

10 eV 10 meV

CDM HDM

Axions Thermal RelicsNon-ThermalRelics

10 eV

CDMHDM

10 GeV

Neutrinos& WIMPs

Thermal Relicslog (Ω𝑎)

Ω𝑀

log (𝑚𝜈)


Neutrino and Axion Hot Dark Matter Limits

Marginalizing over neutrinohot dark matter component

eV (95% CL)

Assuming no axions

eV (95% CL)

Credible regions for neutrino plusaxion hot dark matter(WMAP-7, SDSS, HST)Hannestad, Mirizzi, Raffelt & Wong[arXiv:1004.0695]

95%68%


Axion Bounds

Directsearches

Too muchcold dark matter (classic)

TelescopeExperiments

Globular clusters(a-g-coupling)

Too manyevents

Too muchenergy loss

SN 1987A (a-N-coupling)

Too muchhot dark matter

CAST ADMXCARRACK

Classicregion

Anthropicregion

103 106 109 1012 [GeV] fa

eVkeV meV meVma

neV

1015


New BBN limits on sub-MeV mass axions

Cadamuro, Hannestad, Raffelt & Redondo, arXiv:1011.3694 (JCAP)

• Axions essentially in thermal equilibrium throughout BBN• e+e- annihilation partly heats axions missing photons• Reduced photon/baryon fraction during BBN• Reduced deuterium abundance, using WMAP baryon fraction


Creation of Adiabatic vs. Isocurvature PerturbationsInflaton field Axion field

Slow roll

Reheating

De Sitter expansion imprintsscale invariant fluctuations

Inflaton decay matter & radiationBoth fluctuate the same:Adiabatic fluctuations

Inflaton decay radiationAxion field oscillates late matterMatter fluctuates relative to radiation:Entropy fluctuations

De Sitter expansion imprintsscale invariant fluctuations


Power Spectrum of CMB Temperature Fluctuations

Acoustic Peaks

Sky map of CMBR temperaturefluctuations

Multipole expansion

Angular power spectrum

Δ (𝜃 ,𝜑 )=𝑇 (𝜃 ,𝜑 )− ⟨𝑇 ⟩⟨ 𝑇 ⟩

Δ (𝜃 ,𝜑 )=∑ℓ=0

∞

∑𝑚=−ℓ

ℓ

𝑎ℓ𝑚𝑌 ℓ𝑚 (𝜃 ,𝜑 )

𝐶ℓ= ⟨𝑎ℓ𝑚∗ 𝑎ℓ𝑚⟩= 12 ℓ+1 ∑

𝑚=−ℓ

ℓ

𝑎ℓ𝑚∗ 𝑎ℓ𝑚


CMB Angular Power Spectrum

Purely adiabatic

Purely isocurvature

Hamann, Hannestad, Raffelt & Wong, arXiv:0904.0647


Parameter Degeneracies


WMAP-5WMAP-5 + LSSPlanck forecastCosmic VarianceLimited (CVL)


Isocurvature Forecast

Hubble scale during inflation

Axio

n de

cay

cons

tant



Experimental Tests of Invisible Axions

Primakoff effect:

Axion-photon transition in externalstatic E or B field(Originally discussed for by Henri Primakoff 1951)

Pierre Sikivie:

Macroscopic B-field can provide alarge coherent transition rate overa big volume (low-mass axions)• Axion helioscope: Look at the Sun through a dipole magnet• Axion haloscope: Look for dark-matter axions with A microwave resonant cavity


Search for Solar Axions

g a

Sun

Primakoff production

Axion Helioscope(Sikivie 1983)

gMagnet S

Na

Axion-Photon-Oscillation

Tokyo Axion Helioscope (“Sumico”) (Results since 1998, up again 2008) CERN Axion Solar Telescope (CAST) (Data since 2003)

Axion flux

Alternative technique: Bragg conversion in crystal Experimental limits on solar axion flux from dark-matter experiments (SOLAX, COSME, DAMA, CDMS ...)


Tokyo Axion Helioscope (“Sumico”)

Moriyama, Minowa, Namba, Inoue, Takasu & YamamotoPLB 434 (1998) 147Inoue, Akimoto, Ohta, Mizumoto, Yamamoto & MinowaPLB 668 (2008) 93

m


CAST at CERN


Sun Spot on CCD with X-Rays

ROI

„suspicious pressure“

90 min tracking result


Axion-Photon-Conversion

Stationary Klein-Gordon equationfor photons and axionsin external transverse B-field

−𝑖𝜕𝑧 (𝐴𝑎 )=[𝜔+ 12 ( 0 𝑔𝑎𝛾𝐵

𝑔𝑎𝛾𝐵 𝑚𝑎2 /𝜔)](𝐴𝑎 )

𝑚𝑎=0Conversion probability

𝑃 (𝑎→𝛾 )=(𝑔𝑎𝛾𝐵𝐿2sin (𝑥 )𝑥 )

2

𝑥=√(𝑚𝑎2

4𝜔 )2

+(𝑔𝑎𝛾𝐵𝐿2 )2

Saturation of at for sufficiently largemass eV for CAST)

𝑳𝑩


Helioscope Limits

CAST-I results: PRL 94:121301 (2005) and JCAP 0704 (2007) 010 CAST-II results (He-4 filling): JCAP 0902 (2009) 008


Next Generation Axion Helioscope

• CAST has one of the best existing magnets that one could “recycle” for axion physics (LHC test magnet)

• Only way forward is building a new magnet, especially conceived for this purpose

• Work ongoing, but best option up to now is a toroidal configuration:

– Much bigger aperture than CAST: per bore – Lighter than a dipole (no iron yoke) – Bores at room temperature

I. Irastorza et al., “Towards a new generation axion helioscope”, arXiv:1103.5334


Helioscope Prospects

SN 1987ALimits


Axion-Like Particles (ALPs)Particles with two-photon vertex: Pseudoscalars: • Gravitons• Neutral pions ()• Axions and similar hypothetical particles

Two-photondecay

Γ 𝑎𝛾=𝑔𝑎𝛾

2 𝑚𝑎3

64𝜋

Primakoffeffect

BextStarGalaxy

Magnetically induced vacuumbirefringence

Bext Bext

Vacuum Cotton-Mouton effect

Gravitationallight deflection


Recent “shining-light-through-a-wall” or vacuum birefringence experiments:• ALPS • BMV • BFRT• GammeV • LIPPS • OSQAR • PVLAS

Photon Regeneration Experiment at DESY (ALPS)Ehret et al. (ALPS Collaboration), arXiv:1004.1313

(DESY, using HERA dipole magnet) (Laboratoire National des Champs Magnétiques Intens, Toulouse) (Brookhaven, 1993) (Fermilab) (Jefferson Lab) (CERN, using LHC dipole magnets) (INFN Trieste)


Limits on Axion-Like Particles from Laser Experiments

Ehret et al. (ALPS Collaboration), arXiv:1004.1313

Limits on pseudoscalars, similar plot for scalars


Search for Galactic Axions (Cold Dark Matter)

Power

Frequency ma

Axion Signal

Thermal noise of cavity & detector

Power of galactic axion signal

Microwave Energies (1 GHz 4 meV)

Dark matter axions Velocities in galaxy Energies therefore

ma = 1-100 meV

va 10-3 c

Ea (1 10-6) maAxion Haloscope (Sikivie 1983)

Bext 8 Tesla

Microwave ResonatorQ 105

Primakoff Conversionga

Bext

Cavityovercomesmomentummismatch

4×10−21W 𝑉

0.22m3 ( 𝐵8.5 T )

2 𝑄105×( 𝑚a

2𝜋 GHz )( 𝜌𝑎5×10−25 g / cm 3 )


Axion Dark Matter Searches

Limits/sensitivities, assuming axions are the galactic dark matter

1. Rochester-Brookhaven- Fermilab, PRD 40 (1989) 3153

2. University of Florida PRD 42 (1990) 1297

3. US Axion Search ApJL 571 (2002) L27

4. CARRACK I (Kyoto) hep-ph/0101200

4

123

5. ADMX (US) foreseen RMP 75 (2003) 777

5

6. New CARRACK (Kyoto) K.Imai (Panic 2008)

6


ADMX Hardware

Gianpaolo Carosi, Talk at Fermilab (May 2007)


SQUID Microwave Amplifiers in ADMX

Gianpaolo Carosi, Talk at Fermilab (May 2007)


ADMX phase I: First-year science data (2009)


And if the axion be found? Karl van Bibberat IDM 2008


Fine Structure in the Axion Spectrum• Axion distribution on a 3-dim sheet in 6-dim phase space• Is “folded up” by galaxy formation• Velocity distribution shows narrow peaks that can be resolved• More detectable information than local dark matter density

P.Sikivie& collaborators


CARRACK

Kenichi Imai


New CARRACK (Kyoto)


CARRACK Apparatus

Kenichi Imai


Assume axions are galactic dark matter: 300 MeV/cm3

Independently of expect

Expect time-varying neutron EDM, MHz frequency for GeV

Experimental limit on static EDM

Use much larger electric fields within atoms, small energy shifts withinpolarized molecules: Molecular interferometry techniques may work,a factor 100 off at present. Best in kHz-MHz regime (anthropic window).

Searching for Axions in the Anthropic Window

Graham & Rajendran, arXiv:1101.2691


Summary

• Peccei-Quinn dynamical CP symmetry restoration is better motivated than ever and provides an excellent CDM candidate

• Realistic full-scale search in “classic window” (1-100 meV) is finally beginning (ADMX and New CARRACK)

• Isocurvature fluctuations could still show up (Planck, future CVL probe)

• CAST solar axion search almost complete and has crossed into hot dark matter region. No axions found, new limits.

• Hint for additional cooling in white dwarfs by axions? Leads to significant diffuse supernova axion background (DSAB). Parameters testable with Next Generation Helioscope?

georg raffelt, mpi physics, munich 4 th schrödinger lecture, university vienna, 24 may 2011 axions...

Documents

mpi physics

munich4th schrdinger

university vienna

nobel lecture

maskawa georg raffelt

coefficientgeorg raffelt

years of axions georg

new ingredientsgeorg