Physics Case for Axion or ALP DM. Andreas Ringwald (DESY)

Physics Case for Axion or ALP DM. Andreas Ringwald (DESY) IDM2016 Sheffield, UK, 22-28 July 2016

Introduction > Many dark matter candidates > Strongest physics case based on UV completions of the Standard Model which solve also other problems Hierarchy Problem Neutrino Masses and Mixing Baryon Asymmetry Strong CP Problem > MSSM: Neutralino or Gravitino Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 2

Introduction > Many dark matter candidates > Strongest physics case based on UV completions of the Standard Model which solve also other problems Hierarchy Problem Neutrino Masses and Mixing Baryon Asymmetry Strong CP Problem > MSSM: Neutralino or Gravitino > numsm: Lightest sterile neutrino [M. Shaposhnikov, Phil. Trans. R. Soc. A 373 (2014) 0038] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 3

Introduction > Many dark matter candidates > Strongest physics case based on UV completions of the Standard Model which solve also other problems Hierarchy Problem Neutrino Masses and Mixing Baryon Asymmetry Strong CP Problem > MSSM: Neutralino or Gravitino > numsm: Lightest sterile neutrino > PQSM: Axion < 10 mev 0 0 A Axion [wikipedia] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 4

PQSM: Peccei-Quinn Extensions of the Standard Model > A global (or accidental) U(1) PQ symmetry featuring a chiral anomaly is added to the SM > Symmetry is broken by the vev of a new hidden (SM singlet) scalar field Radial excitation: Nambu-Goldstone boson: the axion > Couplings of axion to SM suppressed by powers of [Raffelt] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 5

PQSM: Peccei-Quinn Extensions of the Standard Model > The field acts as space-time dependent theta parameter and thus solves strong CP problem since QCD dynamics dictates [Peccei,Quinn 77; Weinberg 78; Wilczek 78] > Axion acquires a small mass from mixing with the pion Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 6

Axion-Like Particles (ALPs) > Often, there is more than one global symmetry and therefore more than one Nambu-Goldstone boson Global lepton number symmetry: Majoron [Chikashige et al. 78; Gelmini,Roncadelli 80] Global family symmetry: Familon [Wilczek 82; Berezhiani,Khlopov 90] > Then the particle corresponding to the excitation of the field combination is the axion > Particle excitations of the fields orthogonal to this field combination are called Axion-Like-Particles (ALPs) > String theory suggests a plenitude of ALPs [Witten 84; Conlon 06; Arvanitaki,Dimopoulos,Dubovsky,Kaloper,March-Russell 10; Cicoli,Goodsell,AR 12] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 7

Axion-Like Particles (ALPs) > 4D low-energy effective field theory emerging from string theory predicts natural candidates for the axion, often even an `axiverse, containing many additional ALPs KK zero modes of 10D antisymmetric tensor fields, the latter belonging to the massless spectrum of the bosonic string [Witten 84; Conlon 06; Arvanitaki et al. 09; Acharya et al. 10; Cicoli, Goodsell, AR 12] NGBs from accidental PQ symmetries appearing as low energy remnants of discrete symmetries from compactification [Lazarides,Shafi 86; Choi et al. 09; Dias et al. 14] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 8

Axion/ALP Dark Matter > DM from vacuum realignment: [Preskill et al 83; Abbott,Sikivie 83; Dine,Fischler 83,...] In early universe, axion/alp frozen at random initial value Later, field feels pull of mass towards zero and oscillates around it Spatially uniform oscillating classical field = coherent state of many, extremely non-relativistic particles = CDM > Key quantity: Topological susceptibility, χ[fm -4 ] 10 2 10 0 10-2 10-4 10-6 10-8 [Petrecky et al. `16] 10-1 10-2 10-3 10-4 100 150 200 250 10-10 10-12 [Borsanyi et al. `16] 100 200 500 1000 2000 T[MeV] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 10

Axion/ALP Dark Matter > DM from vacuum realignment: [Preskill et al 83; Abbott,Sikivie 83; Dine,Fischler 83,...] In early universe, axion/alp frozen at random initial value Later, field feels pull of mass towards zero and oscillates around it Spatially uniform oscillating classical field = coherent state of many, extremely non-relativistic particles = CDM > Key quantity: Topological susceptibility, > DM from topological defects Important contribution if PQ symmetry restored after inflation Inflated away if SSB happens before inflation and not restored after [Hiramatsu et al. 12] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 11

Axion/ALP Dark Matter > DM from vacuum realignment: [Preskill et al 83; Abbott,Sikivie 83; Dine,Fischler 83,...] In early universe, axion/alp frozen at random initial value Later, field feels pull of mass towards zero and oscillates around it Spatially uniform oscillating classical field = coherent state of many, extremely non-relativistic particles = CDM > Key quantity: Topological susceptibility, > DM from topological defects Important contribution if PQ symmetry restored after inflation Inflated away if SSB happens before inflation and not restored after Θ 0 10 0 10-1 10-2 10-3 10-4 10 19 10 18 10 17 10 16 10 15 10 14 10 13 10 12 10 11 10 10 pre-inflation initial angle f A [GeV] post-inflation misalignment range 10-6 10-5 10-4 10-3 10-2 10-1 10 0 10 1 10 2 10 3 m A [µev] [Borsanyi et al. `16] 10 9 Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 12

Axion/ALP Dark Matter > DM from vacuum realignment: [Preskill et al 83; Abbott,Sikivie 83; Dine,Fischler 83,...] In early universe, axion/alp frozen at random initial value Later, field feels pull of mass towards zero and oscillates around it Spatially uniform oscillating classical field = coherent state of many, extremely non-relativistic particles = CDM > Key quantity: Topological susceptibility, > DM from topological defects Important contribution if PQ symmetry restored after inflation Inflated away if SSB happens before inflation and not restored after [Arias et al. `12] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 13

SM*A*S*H: Solving Five Problems at One Stroke > may play the role of the inflaton field, if it has a non-minimal coupling to gravity, [Fairbairn et al. `14; Ballesteros et al. `16] [Ballesteros,Redondo,AR,Tamarit, 1607.nnnn] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 14

SM*A*S*H: Solving Five Problems at One Stroke > may play the role of the inflaton field, if it has a non-minimal coupling to gravity, [Fairbairn et al. `14; Ballesteros et al. `16] N=N 0.05 Mpc -1 (quartic oscillations) [Ballesteros,Redondo,AR,Tamarit, 1607.nnnn] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 15

SM*A*S*H: Solving Five Problems at One Stroke > may play the role of the inflaton field, if it has a non-minimal coupling to gravity, [Fairbairn et al. `14; Ballesteros et al. `16] > Augmenting PQSM with three SM singlet neutrinos, getting their Majorana masses also through the vev No strong CP problem Axion dark matter Inflation Neutrino masses and mixing Thermal leptogenesis [Dias et al. `14; Ballesteros et al. `16 ] [Ballesteros,Redondo,AR,Tamarit, 1607.nnnn] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 16

Astro-Hints on Axion/ALPs? > Modest hints for excessive energy losses of stars in various evolutionary stages, photon-alp conversion in astrophysical magnetic fields [Copyright Addison Wesley] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 17

Hints of Axion/ALP Energy Losses of Stars? > Excessive energy losses of Red Giants (RGs), Helium Burning stars (HBs) and White Dwarfs (WDs): HB RG WDLF (M Bol ~9) PG 1351 R 548 G117-B15A -1 0 1 2 3 ΔL/L st [Giannotti,Irastorza,Redondo,AR, arxiv:1512.08108] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 18

Hints of Axion/ALP Energy Losses of Stars? > Excessive energy losses of RGs, HBs and WDs can all be explained at one stroke by production and emission of axion/alp with coupling both to electrons and photons: [Giannotti,Irastorza,Redondo,AR, arxiv:1512.08108] - CAST γ [ - ] - - IAXO HB/RG (1σ) WD+RG (1σ) WD+RG (2σ) ALPS-IIc - - - - - 26 = g 2 ae/(4 )/10 26 α Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 19

Photon ALP Conversion in Cosmic Magnetic Fields? > Gamma ray spectra from distant AGNs should show an energy and redshift dependent exponential attenuation, due to pair production at Extragalactic Background Light (EBL) Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 20

Photon ALP Conversion in Cosmic Magnetic Fields? > Gamma ray spectra from distant AGNs should show an energy and redshift dependent exponential attenuation, due to pair production at Extragalactic Background Light (EBL) > Indication of anomalous gamma transparency: attenuation observed by IACT and Fermi-LAT too small [Aharonian et al. 07; de Angelis,Roncadelli et al. 07;...;Horns,Meyer 12;...;Rubtsov,Troitsky 14] [Horns,Meyer 12] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 21

Photon ALP Conversion in Cosmic Magnetic Fields? > Possible explanation: photon <-> ALP conversions in magnetic fields [De Angelis et al 07; Simet et al 08; Sanchez-Conde et al 09; Meyer,Horns,Raue 13] [Manuel Meyer 12] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 22

Photon ALP Conversion in Cosmic Magnetic Fields? > Possible explanation: photon <-> ALP conversions in magnetic fields [De Angelis et al 07; Simet et al 08; Sanchez-Conde et al 09; Meyer,Horns,Raue 13] [Meyer,Horns,Raue 13] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 23

Photon ALP Conversion in Cosmic Magnetic Fields? > Possible explanation: photon <-> ALP conversions in magnetic fields [De Angelis et al 07; Simet et al 08; Sanchez-Conde et al 09; Meyer,Horns,Raue 13] - CAST γ [ - ] HB/RG (1σ) - IAXO ALPS-IIc - WD+RG (1σ) [Meyer,Horns,Raue WD+RG (2σ) 13] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 24

Photon ALP Conversion in Cosmic Magnetic Fields? > Part of parameter space of interest ruled out by non-observation of spectral irregularities by Fermi-LAT in gamma-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster, due to photon-alp oscillations, at significant level [Fermi-LAT PRL 116 (2016) 161101] Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 25

Photon ALP Conversion in Cosmic Magnetic Fields? > Part of parameter space of interest ruled out by non-observation of spectral irregularities by Chandra in X-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster, at O(30%) level [Berg et al. 16] - 8 Massive Stars - 10 SN1987A γ - Ray Burst ALPS - II Log 10 g a γ [GeV - 1 ] - 12-14 - 16 PIXIE / PRISM B.1 γ - Ray Transparency A Soft X - Ray Excess from Coma C.1 IAXO B.2 C.2 3.55 kev Line from Decaying ALP DM [Berg et al. 16] - 18-40 - 38-36 - 34-32 - 30-28 - 26-24 - 22-20 - 18-16 - 14-12 - 10-8 - 6-4 - 2 0 2 4 6 Log 10 m a [ ev ] [adapted from Carvajal et al. 15] > O(10%) irregularities at 2.2 and 3.5 kev may be explained by ALP with Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 26

Conclusions > Strong physics case for axion and ALPs: Axion and ALPs occur naturally as NG bosons from breaking of well motivated symm. Solution of strong CP problem Candidates for dark matter Explanation of astrophysical hints (energy losses of stars; photon-alp conversions in astrophysical magnetic fields) > Need terrestrial experiments which can probe the parameter space suggested by astro and cosmo hints ALPS II IAXO ADMX Andreas Ringwald Physics Case for Axion or ALP Dark Matter, IDM2016, Sheffield, UK, 18 22 July 2016 Page 27