Dark matter searches Lecture 1. Neutrinos and axions A ... · Dark matter searches Lecture 1. Neutrinos and axions «ETTORE MAJORANA» FOUNDATION AND CENTRE FOR SCIENTIFIC CULTURE

Dark matter searches

Lecture 1. Neutrinos and axions

«ETTORE MAJORANA» FOUNDATION AND CENTRE FORSCIENTIFIC CULTURE

INTERNATIONAL SCHOOL OF SUBNUCLEAR PHYSICS

52nd Course: Status of theoretical understanding and ofexperimental power for LHC physics and beyond

28 June 2014 A. Bettini. Padova University and INFN; LSC 1

A. BettiniCanfranc Underground Laboratory. Spain

G. Galilei Physics Dept. Padua University. ItalyINFN

Dark matter searches

Lecture 1. Neutrinos and axions

A 80-year old unsolved problem

Fritz Zwicky, 1933: “If this [over-density] is confirmed we would arrive at theastonishing conclusion that dark matter {dunkle Materie} is present [in Coma] with amuch greater density than luminous matter.From these considerations it follows that the large velocity dispersion in Coma [andin other clusters of galaxies] represents an unsolved problem.” [S. van den Berghastro-ph/9904 251]


F. Zwicky, Helv. Phys. Acta. 6, 110 (1933).

Dark Matter everywhereDark matter needed at all the scales and in all the epochs, in the same quantityEvidence coming only from gravitational interaction

Galaxy rotation curves

Bullet cluster merger 1E 0657-558Normal matter (X rays) pinkTotal matter (Grav. Lens.) blu


Lars Bergström. Rep. Prog. Phys. 63(2000) 793 hep-ph/0002126

D. Clowe et al., Astr. Journ, 648:L109-L113,2006

CMB. Planck 2013H0=67.3±1.2 km s–1Mp–1≈≈1.5 x 10–42 GeV≈≈ 2.3 x 10–18 s–1

H0=67.3±1.2 km s–1Mp–1≈≈1.5 x 10–42 GeV≈≈ 2.3 x 10–18 s–1


Planck 2013 results. XVI http://arxiv.org/pdf/1303.5076v3.pdf.

h2 H0 km s1Mp1 /100 2 0.45 1 Mpc = 3.1 1022 m

Gravitational LensingThe gravitational field of matter between us and the source deflects its lightAll matter distribution (luminous and dark) can be reconstructed


BICEP 21 km from the South Pole


BICEP2BICEP2 observes in a unique band at 150 GHz[but cross correlation checks with BICEP1maps @ 100 GHz]Telescope in a liquid He cryostat (@ 4 K).Aperture = 26 cmObserved 380 square degRefracting optical system equipped with afocal plane of 512 antenna coupled transitionedge sensor (TES) @ 270 mKOptics tube provides rigid structural supportfor the optical chain.The sub-kelvin focal plane assembly sitswithin a superconducting Nb magnetic shield.


BICEP2 observes in a unique band at 150 GHz[but cross correlation checks with BICEP1maps @ 100 GHz]Telescope in a liquid He cryostat (@ 4 K).Aperture = 26 cmObserved 380 square degRefracting optical system equipped with afocal plane of 512 antenna coupled transitionedge sensor (TES) @ 270 mKOptics tube provides rigid structural supportfor the optical chain.The sub-kelvin focal plane assembly sitswithin a superconducting Nb magnetic shield.

http://bicepkeck.org/b2_respap_arxiv_v1.pdfhttp://www.cfa.harvard.edu/news/2014-05

http://www.cfa.harvard.edu/CMB/bicep2/

BICEP2•Inflation quantum effects @ energies near 1016 GeV, and timescales < 10–32 s.

•Quantization of the gravitational field + exponential expansion primordialbackground of stochastic gravitational waves with a characteristic spectral shape.

•These inflationary gravitational waves (IGW) local quadrupole anisotropies inCMB

•Polarization pattern will include a characteristic non-irrotational component (calledB-mode) at degree angular scales.

•Its amplitude depends upon the tensor-to-scalar ratio, r , which is a function of theenergy scale of inflation.

•However, gravitational lensing between CMB and us induces rot≠0 in the originallyirrotational field (E-mode)

•The IGW B -mode, however, is predicted to peak at multipole l=80 making itpossible to distinguish from lensing effects

PRL 112, 241101 (2014)arXiv:1403.3985v2


•Inflation quantum effects @ energies near 1016 GeV, and timescales < 10–32 s.

•Quantization of the gravitational field + exponential expansion primordialbackground of stochastic gravitational waves with a characteristic spectral shape.

•These inflationary gravitational waves (IGW) local quadrupole anisotropies inCMB

•Polarization pattern will include a characteristic non-irrotational component (calledB-mode) at degree angular scales.

•Its amplitude depends upon the tensor-to-scalar ratio, r , which is a function of theenergy scale of inflation.

•However, gravitational lensing between CMB and us induces rot≠0 in the originallyirrotational field (E-mode)

•The IGW B -mode, however, is predicted to peak at multipole l=80 making itpossible to distinguish from lensing effects

BICEP2B-mode angular spectrumContinuous curve= lensing onlyDotted curve= with fitted B-mode added

PRL 112, 241101 (2014)arXiv:1403.3985v2


H0=67.3±1.2 km s–1Mp–1≈ 1.5 x 10–42 GeVHI= 6.00±0.91 x 1014 GeVH0=67.3±1.2 km s–1Mp–1≈ 1.5 x 10–42 GeVHI= 6.00±0.91 x 1014 GeV

Energy density at inflation V 1/4 2.21016 r0.2 GeV

Caveat.Foreground due to powderspolarisation estimated, not measuredPLANCK 1 year r< 0.11Wait PLANCK delivery (soon?)

Caveat.Foreground due to powderspolarisation estimated, not measuredPLANCK 1 year r< 0.11Wait PLANCK delivery (soon?)

BICEP2. Foreground PRL 112, 241101 (2014)arXiv:1403.3985v2

•Galactic foreground (in the very clean angular range) r<0.01•Polarised powders foreground. No map available, cannot be measured from surface

•Consider different models


Caveat.PLANCK 2013 r< 0.11Wait PLANCK delivery (soon?)

Caveat.PLANCK 2013 r< 0.11Wait PLANCK delivery (soon?)

Three candidates consideredDark matter is a big challenge for particle physics

A large number of candidates for dark matter have been imagined

We shall consider three of them, which require

less radical enlargement of the Standard Model

less arbitrary assumptions

•Right neutrinos (meaning negative chirality = γ5 eigenvalue)

•keV mass sterile neutrinos

•Axions (different fromAxion Like Particles, ALPs)

•Sub-meV mass pseudoscalar particle

•WIMPs

•SUSY neutralinos, assuming R parity conservation


Dark matter is a big challenge for particle physics

A large number of candidates for dark matter have been imagined

We shall consider three of them, which require

less radical enlargement of the Standard Model

less arbitrary assumptions

•Right neutrinos (meaning negative chirality = γ5 eigenvalue)

•keV mass sterile neutrinos

•Axions (different fromAxion Like Particles, ALPs)

•Sub-meV mass pseudoscalar particle

•WIMPs

•SUSY neutralinos, assuming R parity conservation

Three neutrinos from LEP

LEPThe line shape of the Zwidth becomes largerpeak becomes lowerwith increasing neutrinos numbers


N 2.984 0.008

Three neutrinos from cosmology

Neff 3.360.34

“effective” neutrino density=density of non interactingradiation (m < MeV) at decoupling.

Prediction of SM = N νeff=3.046 [Mangano et al. hep-ph 0506164]

Planck + CMB at High L + Polarisation (WP)

Cosmology gives two pieces of information on neutrinos

ν


Neff 3.360.34

3 favoured, 4 not excluded

Upper limits on the sum of neutrino masses

m 0.66 eV (95%; Planck+WP+highL)

m 0.23 eV (95%; Planck+WP+highL+BAO)

During the large scale structureformation neutrinos velocities arelarger than the escape velocities fromthe smaller (galaxy clusters) structuresFreely streaming out, they slow downtheir growthEffect not seen limit on sumneutrino mass

Tighter constraint adding BAO

Neff 3.300.27ν

ν

ν

More than three?nmne appearanceContradictory “evidence” reported by LSND & MiniBoonE?Large systematic uncertaintiesLSND (1995) observed a 3.8 σ excess in anti νµanti νe. If oscillation ∆m2>0.2 eV2.KARMEN (2001) excluded almost all the LSND parameter spaceMiniBooNE (2007-9). νµνe. Higher E, same L/E. NO signal @ LSND claim. Excess at lowenergies, where background model is most uncertain, not compatible with oscillationsMiniBoone (2010) anti νµanti νe claims signal in oscillation region observing excess of20.9±14.0 events


MiniBooNEarXiv:1207.4809v2

OPERA arXiv:1303.3953

ICARUS arXiv:1209.0122

Larger mixing regionexcluded by CNGS

ICARUSNeutrino 2014

More than three?nmne appearance

Larger mass region excludedby cosmology

15A. Bettini.

“neutrinos” are weakly interacting particles behaving as radiation @ decouplingLimits valid for masses <1 MeV“Neutrinos” saturate dark matter density for Σm≈10 eVHeavier “neutrinos” must be out of thermal equilibrium

S. Tremaine and J. E. Gunn, Phys. Rev. Lett. 42, 407 (1979)

More than three?ne disappearance

Gallium anomaly?Both GALLEX/GNO and SAGE performed two runs each with radioactive neutrino sourcesfor checking the overall extraction efficiencyAveraging (!?) the four ratios found/expected one finds R=0.86±0.05Neither experiment used R to calibrate due to due to the uncertainties in theνe+71Ga71Ge+e– (detector) and e– +51Cr51V+νe (source) cross sectionsTo be tested by Borexino + source


Gallium anomaly?Both GALLEX/GNO and SAGE performed two runs each with radioactive neutrino sourcesfor checking the overall extraction efficiencyAveraging (!?) the four ratios found/expected one finds R=0.86±0.05Neither experiment used R to calibrate due to due to the uncertainties in theνe+71Ga71Ge+e– (detector) and e– +51Cr51V+νe (source) cross sectionsTo be tested by Borexino + source

More than three?ne disappearanceReactor antineutrino anomaly?2011. Th. A. Mueller et al. [Phys. Rev., C83:054615] re-evaluation of the reactor antineutrino flux.Up by 3%, with a systematic uncertainty of about 5%2011. G. Mention et al.[ Phys. Rev., D83:073006]: the average of the measured flux at distances <100 m accounts for only 0.943± 0.023 (2.5s). Claim evidence for sterile neutrino (!!)2013. C. Zhang et al. [Phys. Rev. D 87, 073018]. Nowq13 is known. Calculate flux at the distancesof the measurements. Extrapolate to 0 distance.0.959± 0.009 (exp)± 0.027(syst) of the Mueller re-evaluation; difference is 1.4sRecently (Neutriono 2014) confirmed by Daya Bay experiment


Neutrino masses

Neutrino masses, which are not inthe Standard Model, looksubstantially different from theother partiles


Neutrino masses, which are not inthe Standard Model, looksubstantially different from theother partiles

See-saw mechanism

MRTR

Assume neutrinos are Majorana particlesMajorana mass term allowed by SU2 x U1

L and L–B violation ate scale M, very large

Dirac mass term mDLR mD M

0 mDmd M


0 mDmd M

Eigenvalues mlight mD

2

Mmheavy M

With mD≈VEV=υ ≈ 200 GeVmlight≈ 100 meVM ≈ 1014 - 1015 GeVClose to GUT and (BICEP2) inflation scales !!

νSMA. Boyarsky, O. Ruchayskiy, M. ShaposhnikovarXiv 0901:0011

•3 right neutrinos•A degenerate doublet 100 MeV scale•A singlet N1 at keV scale•Small neutrino masses “explained” bysmall Yukawa couplings (|y2|<10–13)

mlight ylight

2 2

M; mheavy M


•N1 “explains” dark matter•Astrophysical and LEP limits areevaded assuming very smallmixing (q2<10–8)•N1 decouples from and is not inthermal equilibrium wit the rest•Decays N1 ν + γand otherchannels

νSMA. Boyarsky, O. Ruchayskiy, M.Shaposhnikov arXiv 0901:0011


keV neutrino?arXiv:1402:2301

“Evidence” in a stacked XMMspectrum of 73 galaxy clusters withred-shifts 0.01 < z < 0.35Marginally statistically significant(about 3 σ)Corresponds to a minimum of theeffective detection areaDepends on the (concave) shape ofthe background modelDiscrepancies between line positionand intensity in different sub-samples


“Evidence” in a stacked XMMspectrum of 73 galaxy clusters withred-shifts 0.01 < z < 0.35Marginally statistically significant(about 3 σ)Corresponds to a minimum of theeffective detection areaDepends on the (concave) shape ofthe background modelDiscrepancies between line positionand intensity in different sub-samples

mN= 7 keVq2 2 x 10–11

Next generation X-ray observatories(Astro-H) needed for a sensitive search

The strong CP problem

L

s8

12

G

G

s8

%GG

The QCD symmetry properties allow the presence in the Lagrangian of the term (G isthe gluon field strength)

that is pseudoscalar (violates P), changes sign under time reversal, hence violates CPNB. Corresponding term in electrodynamics can be eliminated, being AbelianThe phases in the mass term

Lm

s8

Arg DetM %GG

would violate CP too, but can be eliminated by a phase rotation. The physically meaningfulquantity is


argdetM

It gives a time reversal violating neutron dipole momentdn / e : 1016 cm

The experimental limit |dn|/e <2.9 x 10–26 cm, corresponds to the extremely small upper limit

< 1010

Why isqso small?

would violate CP too, but can be eliminated by a phase rotation. The physically meaningfulquantity is

Peccei QuinnMake theqparameter dynamical introducing a new pseudoscalar fieldfa

Assume that the Lagrangian originally possesses a U(1) invariance involving the quarks Yukawacouplings.The U(1) symmetry spontaneously breaks down at the energy scale fa

L s8

%GG

afa


R. D. Peccei and H. R. Quinn. Phys Rev Lett 38 (1977) 1440

The valley is extremely narrow, with a huge curvature. Very high frequency field oscillationsperpendicular to the valley correspond to very large masses and decay immediatelyOscillations along the canyon have zero frequency, corresponding to massless Goldston boson,the axion

a x,t fa x,t

Peccei QuinnQCD axial (ABJ) anomaly ('t Hooft) in non Abelian theories one vacuum state is chosenamong an infinity of possible vacua.The potential corresponds to a particular choice of the phase of the scalar vacuum expectationvalue.This phase appears in the fermion mass termsPQ showed that when all fermion masses are made real by rotations of the fermion fields, theresulting θ is zero.

The θ-term in the QCD Lagrangian can then be eliminated by absorbing it into the axion field,


R. D. Peccei and H. R. Quinn. Phys Rev Lett 38 (1977) 1440

The θ-term in the QCD Lagrangian can then be eliminated by absorbing it into the axion field,

a a faThe topological charge densityinduced by topological fluctuationsof the gluon fields such as QCDinstantons, provides a potential forthe axion field which is minimized atzero expectation value

a 0

This second phase transition happens when the temperature is about ΛQCD

Invisible axions modelsIn the original PQ paper fa was tied to the EW breaking scaleThis was subsequently ruled out by the experiments

Models were later developed in which fa >> VEVma and the axion coupling to other particles very small: “Invisible axions”Extend SM with additional Higgs bosons, and/or fermions with PQ charge

In particular

KSVZ: J. E. Kim [Phys Rev Lett. 43 (1979) 103], M. Shifman, A. Vainstein, V. Zacharov[Nucl Phys B 166 (1980) 493]Additional heavy quarks with PQ-charges

DSZ: M. Dine, W. Fischler, M. Srednicki [Phys Lett B 104 (1981) 199, A. R. Zhitniski[Sov. J. Nucll. Phys. 31 (1980) 260]Two Higgs doublets, normal quarks and leptons have PQ charges


Models were later developed in which fa >> VEVma and the axion coupling to other particles very small: “Invisible axions”Extend SM with additional Higgs bosons, and/or fermions with PQ charge

In particular

KSVZ: J. E. Kim [Phys Rev Lett. 43 (1979) 103], M. Shifman, A. Vainstein, V. Zacharov[Nucl Phys B 166 (1980) 493]Additional heavy quarks with PQ-charges

DSZ: M. Dine, W. Fischler, M. Srednicki [Phys Lett B 104 (1981) 199, A. R. Zhitniski[Sov. J. Nucll. Phys. 31 (1980) 260]Two Higgs doublets, normal quarks and leptons have PQ charges

Axion properties

ma

mu /md1mu /md

fm

fa; 6 meV 109 GeV

fa

If fa is very large, the axion is a veryweakly interacting sub-eV mass particle.It can contribute to dark matter

Axion is coupled to the photon

Ga4F%Fa GaE Ba

Axion is the Goldston boson of the broken PQ U(1) symmetryAxions have predictable properties, which depend mainly on faAxion mass is inversely proportional to fa


Ga ; n

2 fa

mam

: 1Ga

2 ma3

1ma

5Axion decay in two photons = age of the universe for ma=20 eVOnly very small mass axions canbe dark matter

Coupling to fermionsC f2 fa

f5 fa Cf model dependent coefficient

n: number, order of 1

Axions couple to baryons and mesons too

Axion detection

Axions may be produced in the stars by Primakoff effectIn the Sun energy spectrum has a maximum at 3 keVFlux on earth

a Ga 1010 GeV 2 3.751015 m2s1


Can be detected converting back to photons, X rays,in a strong magnetic filed

Neither axions or photons are propagation eigenstatesAxion-photon conversion should be viewed as an oscillationIt is at the basis of their detection

Bounds from astrophysics


Axion photon coupling axion radiation by astrophysical bodiesToo large energy loss contradicts observed stellar evolution limits on the coupling

Where are the axions?

Scenario A.PQ symmetry breaks before inflation

fa >1038 GeV10–12 < ma < 10–2 eV

EXCLUDED


fa >1038 GeV10–12 < ma < 10–2 eV

EXCLUDED

ma: axion massfa: energy scale of the breakdownma: axion massfa: energy scale of the breakdown

Scenario B.PQ symmetry breaks after inflationCosmic defects may decay to axions witha relative weightadec=0.2-200

fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7

ma = (71±0.2) (1+adec)6/7 µeV

Axion mass is now predicted in anarrow range70 µeV < ma < 1.2 meV


fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7

ma = (71±0.2) (1+adec)6/7 µeV


r 0.20.050.07

The BICEP2 measurement of the tensor to scalar ratiosharpens to a narrow mass range the predictions of the PQtheory

gives Hubble parameter at the inflation H I 61014 GeV and fa = 1015 GeV


L. Visinelli and P. Gondolo arXiv: 1403.4594


fa >1038 GeV10–12 < ma < 10–2 eV

EXCLUDED


fa >1038 GeV10–12 < ma < 10–2 eV

EXCLUDED


fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7

ma = (71±0.2) (1+adec)6/7 µeV



fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7

ma = (71±0.2) (1+adec)6/7 µeV


CAVEAT: wait for confirmation or rebuttal by PlanckCAVEAT: wait for confirmation or rebuttal by Planck

Narrow window for axions


Helioscopes and DM detectros look at too large masses and too large couplingsIf BICEP2 is right ADMX looks at too small masses

20 GHz ma / 2

Axion parameter spaceYellow excluded before BICEP2BICEP2: fa = 1015 GeVexcludes region on the leftColoured lines in the region on theright correspond to different modelsof axion production throughtopological defects decays

fa≈ 1012-1014 MeVma≈ 10–8-10–10 MeV


CAST ma 0.1-1 eVIAXO ma 0.01-1 eV

fa≈ 1012-1014 MeVma≈ 10–8-10–10 MeV

fama 104 MeV2 mQCD QCD2

Large scales – small scales


m VEV 2

M N

ma QCD

2

fa

HelioscopesAxion energy few (keV) photon frequency O(1018 Hz: X-rays)

a Ga 1010 GeV 2 3.751015 m2s1


CAST


Fanourakis CTEQ 2006

CAST p

2 Neqe

2

0me

k2 2 – p2

In its 1st phase CAST did not reach the axion regionIn its 2nd phase, the magnet was filled of 4He and subsequently 3He gasNe = number of electrons (free and bound) per cubic metreDispersion relation of the light above the plasma frequency (X-rays)

Photons behave a “free particles” on masswpCan be changed (scanned) by changing the gas pressureAt level crossing a togconversion probablity resonates

KSVZ axion reached, but atlarge mass (1 eV scale)


M. Arik et al. Phys. Rev. Lett. 112, 091302, arXiv: 1307.1985

IAXO. International Axion ObservatoryLetter of Intent to CERN SPSC-I-242Same principles as for CAST, with several improvementsProjected sensitivity still around 0.1 eV masses


Existing boundsAstrophysical bounds come primarily from not having observed effect on star evolution ofaxion radiation


Axion Haloscope


How ADMX works


Gray Rybka - TAUP 2013 - Asilomar, CA - Sept. 10, 2013

ADMX Tuning rods


ADMX. Results


Gray Rybka - TAUP 2013 - Asilomar, CA - Sept. 10, 2013

ADMX. Next stepsScan speed to be increased by factor 100Scan speed ≈ 1/TnoiseReduce both physical and amplifier noise


ADMX. Next steps

Higher frequency (10-100 GHz) resonators neededR&D programme ongoing by ADMXIncluding open resonators


Gray Rybka TAUP 2013

Axions & photonsPropagation eigenstates are superpositions of the axion and electromagnetic fieldsIn an external magnetic field

2 k2 1 00 1

0 gaB

gaB ma2

A||

a

L ga4F%F gaB E

axion mixes with the A component parallel to the magnetic field


Jaeckel and Redondo, arXiv:1308.1103

;gaBma

Dish experimentFocus light-axion wave with a spherical mirror in a strong magnetic fieldSensitivity dominated by S/N

DetectorCryogenic toreduce noise

Horns et al , JCAP04(2013)016

Assumequantum limit of the squid temperatureis reachedMirror area A=10 m2

Magnetic field B = 4 TBandwidth ∆w/w=106

Exposure life = 1 yrAxion mass ma=10 µeVSignal/Noise ≈ 14


Jaeckel and Redondo, arXiv:1308.1103

DetectorCryogenic toreduce noise

Assumequantum limit of the squid temperatureis reachedMirror area A=10 m2

Magnetic field B = 4 TBandwidth ∆w/w=106

Exposure life = 1 yrAxion mass ma=10 µeVSignal/Noise ≈ 14

Signal proportional to ma–3/2

Axions in dwarf galaxiesMany dwarf galaxies exist in the local groupSome of them do not emit much light but appear reach of dark matterSignature for two-photon decay of axions is a very narrow and very weak line at ma /2Expect very narrow line ∆ν/ν 6


Axions in dwarf galaxiesSearch with the Haystack radio observatory (on three dwarf galaxies)B.D. Blout et al., Astrophys. J. 546, 825 (2001)


In the interesting axion mass rangeNeed improving sensitivity in ga by 5-6 orders of magnitudesUse larger telescopes.Progress in cryogenic detectors technique

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Dark matter searches Lecture 1. Neutrinos and axions A ... · Dark matter searches Lecture 1. Neutrinos and axions «ETTORE MAJORANA» FOUNDATION AND CENTRE FOR SCIENTIFIC CULTURE