Implications of the positron/electron excesses on Dark Matter - - PowerPoint PPT Presentation
Implications of the positron/electron excesses on Dark Matter properties 1) The data 2) DM annihilations? 3) and constraints 4) DM decays? Alessandro Strumia, GGI, March 23, 2010 Indirect signals of Dark Matter DM DM annihilations in
1) The data 2) DM annihilations? 3) γ and ν constraints 4) DM decays? Alessandro Strumia, GGI, March 23, 2010
DM DM annihilations in our galaxy might give detectable γ, e+, ¯ p, ¯ d.
DM velocity: β ≈ 10−3. DM is spherically distributed with uncertain profile: ρ(r) = ρ⊙
r⊙
r
γ
1 + (r⊙/rs)α 1 + (r/rs)α
(β−γ)/α
r⊙ = 8.5 kpc is our distance from the Galactic Center, ρ⊙ ≡ ρ(r⊙) ≈ 0.38 GeV/cm3, DM halo model α β γ rs in kpc Isothermal ‘isoT’ 2 2 5 Navarro, Frenk, White ‘NFW’ 1 3 1 20 ρ(r) is uncertain because DM is like capitalism according to Marx: a gravitational system (slowly) collapses to the ground state ρ(r) = δ(r). Maybe our galaxy, or spirals, is communist: ρ(r) ≈ low constant, as in isoT.
0.001 0.01 0.1 1 10 100 0.001 0.1 10 1000 Galactocentric radius r in kpc DM density Ρ in GeVcm3 Earth isoT Burkert Einasto, Α 0.17 NFW Moore
N-body simulations suggest that DM might clump in subhalos: Annihilation rate ∝
dV ρ2 increased by a boost factor B = 1 ↔ 100 ∼ a few
Simulations neglect normal matter, that locally is comparable to DM.
Φe+ = ve+f/4π where f = dN/dV dE obeys: −K(E) · ∇2f − ∂ ∂E( ˙ Ef) = Q.
2
ρ
M
2
σvdNe+ dE from DM annihilations.
˙ E = E2 · (4σT/3m2
e)(uγ + uB).
Propagation model δ K0 in kpc2/Myr L in kpc Vconv in km/s min 0.85 0.0016 1 13.5 med 0.70 0.0112 4 12 max 0.46 0.0765 15 5
min med max
Small diffusion in a small volume, or large diffusion in a large volume? Main result: e± reach us from the Galactic Center only in the max case
The data
e±, p±, He, B, C... Their directions are randomized by galactic magnetic fields B ∼ µG. The info is in their energy spectra. We hope to see DM annihilation products as excesses in the rarer e+ and ¯ p. Experimentalists need to bring above the atmosphere (with balloons or satel- lites) a spectrometer and/or calorimeter, able of rejecting e− and p. This is difficult above 100 GeV, also because CR fluxes decrease as ∼ E−3. Energy spectra below a few GeV are ∼useless, because affected by solar activity.
Consistent with background
100 101 102 103 106 105 104 103 102 101 p kinetic energy T in GeV p flux in 1m2sec sr GeV BESS 9597 BESS 98 BESS 99 BESS 00 WizardMASS 91 CAPRICE 94 CAPRICE 98 AMS01 98 PAMELA 08
Future: PAMELA, AMS
PAMELA is a spectrometer + calorimeter sent to space. It can discriminate e+, e−, p, ¯ p, . . . and measure E up to ∼200 GeV. e− are primaries and e+ secon- daries, so e+/e− decreases as the containment time τ ∼ E−δ. Spectra below 10 GeV distorted by the present solar polarity. Growing excess above 10 GeV
1 10 102 103 1 10 3 30 Energy in GeV Positron fraction PAMELA 09 HEAT 9495 CAPRICE 94 AMS01 MASS 91
The PAMELA excess suggest that it might manifest in other experiments: if e+/e− continues to grow, it reaches e+ ∼ e− around 1 TeV...
These experiments cannot discriminate e+/e−, but probe higher energy.
102 103 104 0.01 0.003 0.03 Energy in GeV E3eeGeV2cm2sec FERMI HESS08 HESS09 ATIC08
Hardening at 100 GeV + softening at 1 TeV Are these real features? Likely yes. Hardening also in ATICs. Systematic errors, not yet defined, are here incoherently added bin-to-bin to the smaller statistical error, allowing for a power-law fit.
1) Maybe secondaries are produced in the acceleration region: then e+/e− can grow with E, but also ¯ p/p, B/C, Ti/Fe... 2) A pulsar is a neutron star with a rotating intense magnetic field. The result- ing electric field ionizes and accelerates e− → γ → e+e−, that are presumably further accelerated by the pulsar wind nebula (Fermi mechanism).
Epulsar = −B2
surfaceR2ω4/6c3 = magnetic dipole radiation.
Known nearby pulsars (B0656+14, Geminga, ?) would need an unplausibly (?) large fraction ǫ of energy that goes into e±: ǫ ∼ 0.3. Test: angular anisotropies (but can be faked by local B( x), pulsar motion).
Model-independent theory of DM indirect detection
Indirect signals depend on the DM mass M, non-relativistic σv, primary BR: DM DM →
W +W −, ZZ, Zh, hh Gauge/higgs sector e+e−, µ+µ−, τ+τ− Leptons b¯ b, t¯ t, q¯ q quarks, q = {u, d, s, c} No γ because DM is neutral. Direct detection bounds suggest no Z. The energy spectra of the stable final-state particles e±, p∓,
(ν)
e,µ,τ,
¯ d, γ depend on the polarization of primaries: WL or T and µL or R. The γ spectrum is generated by various higher-order effects: γ = (Final State Radiation) + (one-loop) + (3-body) We include FSR and ignore the other comparable but model dependent effects
Non-relativistic s-wave DM annihilations can be computed in a model-independent way because they are like decays of the two-body D = (DM DM)L=0 state. If DM is a fundamental weakly-interacting particle, its spin J can be 0, 1/2 or 1, so the spin of D can only be 0, 1 or 2: 1 ⊗ 1 = 1, 2 ⊗ 2 = 1asymm ⊕ 3symm, 3 ⊗ 3 = 1symm ⊕ 3asymm ⊕ 5symm So:
µν and to
higgs Dh2, not to light fermions: DℓLℓR is mℓ/M suppressed.
PAMELA motivates a large σ(DM DM → ℓ+ℓ−): only possible for Dµ[¯ ℓγµℓ].
DfLfR + h.c. = D ¯ ΨfΨf with Ψf = (fL, ¯ fR) in Dirac notation. It means zero helicity on average, and is typically suppressed by mf/M. Huge weak corrections if M ≫ MW.
Dµ[ ¯ fLγµfL]
Dµ[ ¯ fRγµfR] i.e. fermions with Left or Right helicity. Decays like µ+ → ¯ νµe+νe give e+ with dN/dx|L = 2(1 − x)2(1 + 2x) dN/dx|R = 4(1 − x3)/3
0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.5 1.0 1.5 2.0 Positron energy fraction x dNdxN Μ with negative helicity Μ with positive helicity
DFµνǫµνρσFρσ and DF 2
µν
give vectors with Tranverse polarization (with different unobservable helicity corre- lations), that decay in f ¯ f with E = x M as: dN/d cos θ = 3(1 + cos2 θ)/8 dN/dx = 3(1 − 2x + 3x2)/2,
µ
gives Longitudinal vectors (accon- ting for DM annihilations into Higgs Gold- stones), that decay as dN/d cos θ = 3(1 − cos2 θ)/4 dN/dx = 6x(1 − x).
0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Fermion energy fraction x dNdxN Transverse vector Longitudinal vector
Two-body primary channels: e, µL, µR, τL, τR, WL, WT, ZL, ZT, h, q, b, t.
10 102 103 106 105 104 103 Energy in GeV Positron fraction
e
e Μ ΤL ΤR q b t WT WLZTZL h 10 102 103 107 106 105 Energy in GeV Antiproton fraction
p
q b t WT WL ZT ZL h 10 102 103 102 101 1 10 Energy in GeV dlogNΓdlogE
Γ
1 10 102 103 1010 109 108 Energy in GeVnucleon T dddT in 1m2sec sr
d
q b t W Z h
Annihilations into leptons give qualitatively different energy spectra.
¯ d forms when DM produces a ¯ p and a ¯ n with momentum difference below p0 ≈ 160 MeV. The analytical appoximation assuming spherical-cow events dN¯
d
dT¯
d
= p3 3k¯
dmp
dN¯
n,¯ p
dT
2
T=T¯
d/2
misses the jet structure of events, such that N¯
d ∝ 1/M2 is very wrong.
Relativity demands that higher M boosts ¯ p, ¯ n, ¯ d, leaving N¯
d ∼ constant.
Running PYTHIA on GRID we find orders of magnitude enhancement:
102 103 104 107 106 105 104 103 DM mass in GeV Total d yield Spherical approximation MonteCarlo tt bb qq hh ZZ WW
Implications of the data
Ai and pi = 0 ± 0.05, and marginalize over Ai, pi.
±6% at 10 GeV, ±30% at 1 GeV.
(MED is favored?).
100 1000 10000 300 3000 30000 5 10 15 20 DM mass in GeV Χ2 e ΜL ΜR ΤL,R q WT WL ZT ZL h
h ZL ZT WL WT t b q ΤR ΤL ΜR ΜL e
If M > TeV everything fits. At smaller M only annihilations into leptons or W.
100 1000 10000 300 3000 30000 1 10 102 103 104 105 106 1025 1024 1023 1022 1021 1020 DM mass in GeV Boost factor Be Be Σv in cm3sec
h ZL ZT WL WT t b q ΤR ΤL ΜR ΜL e
σv larger than what suggested by cosmology by a factor Be
Thermal DM reproduces the cosmological DM abundance ΩDMh2 ≈ 0.11 for σv ≈ 3 × 10−26 cm3/sec around freeze-out, i.e. v ∼ 0.2. up to co-annihilations and resonances. Possible extrapolations to v ∼ 10−3:
0.001 0.01 0.1 0.0003 0.003 0.03 0.3 1029 1028 1027 1026 1025 1024 1023 DM velocity v Σv in cm3sec v at cosmological freezeout v in our galaxy swave pwave Sommerfeld pwave Sommerfeld swave
101 1 10 102 103 101 1 10 102 103 Αv ΑΕ MMVΑ 1.3 2 3 5 10 30 100 1000
The Sommerfeld effect is the quantum analogous of this classical effect: the sun attracts slower bodies, enhancing its cross section: σ = πR2
⊙(1+v2 escape/v2)
If DM is thermal PAMELA needs s-wave + Sommerfeld and/or a boost factor (DM in sub-halos has small velocity dispersion: Sommerfeld boosts the boost)
E.g. a wino that with M ≈ 100 GeV annihilates into W +
T W − T with the correct
σv = g4
2(1 − M2 W/M2)3/2
2πM2(2 − M2
W/M2)2
Problematic with PAMELA ¯ p, reconsidered by Kane et al., excluded by FERMI.
10 102 103 104 1 10 0.3 3 30 Positron energy in GeV Positron fraction background? PAMELA 08
102 103 104 103 102 101 Energy in GeV E3eeGeV2cm2sec HESS08 ATIC08 PPBBETS08 EC ?
10 102 103 104 105 104 103 102 p kinetic energy in GeV pp background? PAMELA 08
DM with M 150 GeV that annihilates into WW
Assuming equal boost & propagation for e+ and ¯ p (otherwise everything goes):
100 1000 10000 300 3000 30000 15 20 25 30 35 40 DM mass in GeV Χ2 e ΜL ΜR ΤL ΤR t WL
h ZL ZT WL WT t b q ΤR ΤL ΜR ΜL e
DM must annihilate into leptons or into W, Z with M > ∼ 10 TeV Indeed a W at rest gives ¯ p with Ep > mp. So a W with energy E = M gives Ep > Mmp/MW, above the PAMELA threshold for M > 10 TeV.
1000 10000 300 3000 30000 20 25 30 35 40 45 50 DM mass in GeV Χ2
DM annihilation
4e 4Μ 4Τ ΜΜ ΤΤ qq bb pulsar with EpeEM 4Μsh
Compatible if DM has few TeV mass and annihilates into some leptons
102 103 104 1 10 3 30 Positron energy in GeV Positron fraction background? PAMELA 09
102 103 104 0.01 0.003 0.03 Energy in GeV E3eeGeV2cm2sec FERMI HESS08 HESS09 0.01 0.1 1 10 100 1000 108 107 106 105 Photon energy in GeV E2 dΓdE in GeVcm2sec sr FERMI09 brem IC star dust CMB
DM with M 3. TeV that annihilates into ΤΤ with Σv 1.8 1022 cm3s
(Neutralinos and standard DM models can hardly fit the e± excesses). DM is charged under a dark gauge group, to get the Sommerfeld enhancement. DM annihilates into the new vector. If light, m < ∼ GeV, it can only decay into the lighter leptons. Large σ(DM DM → ℓ+ℓ+ℓ−ℓ−) obtained.
102 103 104 1 10 3 30 Positron energy in GeV Positron fraction background? PAMELA 09
102 103 104 0.01 0.003 0.03 Energy in GeV E3eeGeV2cm2sec FERMI HESS08 HESS09 0.01 0.1 1 10 100 1000 108 107 106 105 Photon energy in GeV E2 dΓdE in GeVcm2sec sr FERMI09 brem IC star dust CMB
DM with M 3. TeV that annihilates into 4Μ with Σv 7.7 1023 cm3s
Smoother e± spectrum good for FERMI γ brehmstralung reduced from ln M/mℓ to ln m/mℓ
γ has a mixing θ with the new light vector, giving a σ(DM N) which is too large if elastic or invisible or consistent with DAMA if inelastic thanks to a ∆M > ∼ 100 keV splitting among Re DM and Im DM induced by the dark higgs. Sensitivity to θ, m can be best improved by e beam-dump experiments.
Bounds from γ, ν indirect detection
DM DM → ℓ+ℓ− is unavoidably accompanied by photons:
Largest Eγ ∼ M, probed by HESS.
˙ E ∝ uγ. Intermediate Eγ′ ∼ Eγ(Ee/me)2 ∼ 50 GeV being probed by FERMI.
˙ E ∝ uB = B2/2. Small Eγ ∼ 10−6 eV, probed by radio-observations: Davies, VLT, WMAP.
dΦγ dΩ dE = 1 2 r⊙ 4π ρ2
⊙
M2
DM
JσvdNγ dE , J =
ds r⊙
ρ⊙
2
J∆Ω =
NFW Einasto isoT region ∆Ω 14700 7600 14 Galactic Center 1 · 10−5 2400 3000 14 Galactic Ridge 3 · 10−4
106 104 102 1 102 104 106 104 102 1 102 104 106 r in pc Ρr in pc GeVcm3 isoT Einasto, Α 0.17 NFW Moore IRGC radioGC ΓGalactic Center ΓGalactic Ridge ΓFERMI Earth
1 10 1013 1012 1011 Γ energy in TeV E2 dNΓdE in TeVcm2sec
a M 10 TeV into WW, Galactic Center
1 10 1011 1010 109 108 107 106 Γ energy in TeV dNΓdE in 1cm2sec TeV sr
b M 1 TeV into ΜΜ, Galactic Ridge
DM signals computed for NFW and σv = 10−23 cm3/sec. We conservatively impose that no point is exceeded at 3σ: so the 1st example above is allowed. Other bounds from DM-dominated dwarf spheroidals around the Milky Way.
Galactic e± diffuse (I = 1) while loosing most of their energy as eγ → e′γ′ Eγ′ ∼ Eγ E2
e
m2
e
∼ 30 GeV Initial γ: i) Eγ ∼ eV from star-light; ii) Eγ ∼ 0.1 eV from dust rescattering; iii) Eγ ∼ meV from CMB. ICγ dominate over FSRγ at FERMI E
0.01 0.1 1 10 100 1000 1108 5108 1107 5107 1106 5106 1105 Photon energy in GeV E2 dΓdE in GeVcm2sec sr FERMI09 I1 approx Full res.
Point sources and hadron contamination (around 100 GeV) still present. No clear excess. Robust bounds imposing DM < exp in all sky and energy regions:
14 10 14 15 15 17 18 15 9 13 11 11 11 16 14 13 30 33 20 19 29 27 25 26 15 20 33 31 71 63 49 45 66 59 53 64 51 50 86 65 84 133 100 102 84 103 85 99 112 156 188 117 106 199 119 110
180 90 135 45 10 20 0 10 20 45 90 135 180 90 45 10 20 5 5 10 20 45 90 Galactic longitude in degrees Galactic latitude b in degrees
IC bound on ΣvDM DM ΜΜ in 1023cm3sec for M 1.3 TeV isothermal DM profile with L 4 kpc
global fit: χ2 =
all bins
(ΦDM
i
− Φexp
i
)2 δΦ2 Θ(ΦDM
i
− Φexp
i
) < 9
(ν)
µ scattering in the rock below the detector produce trough-going µ±
Φµ ≈ r⊙σv 8π ρ2
⊙
M2 3G2
FM2p
παµ · J · ∆Ω ·
1
0 dx x2dNν
dx where p ∼ 0.125 is the momentum fraction carried by each quark in the nucleon and αµ = 0.24 TeV/kmwe = −dE/dℓ is the µ± energy loss. The total µ± rate negligibly depends on the DM mass M. SuperKamiokande got the dominant bounds in cones up to 30◦ around the GC Φµ < 0.02/cm2s
Around the GC magnetic fields B contain more energy than light, diffusion and advection seem negligible, so all the e± energy E goes into synchrotron
determines the maximal νsyn:
106 104 102 1 102 104 106 104 102 1 102 104 r in pc B in Gauss constant B equipartition B
dWsyn dν ≈ 2e3B 3me δ( ν νsyn − 1) where νsyn = eBE2 4πm3
e
= 1.4 MHzB G
p
me
2
. Davies 1976 oservations at the lower ν = 0.408 GHz give the robust and dom- inant bound as the observed GC radio-spectrum is harder than synchrotron: νdWsyn dν = σv 2M2
⊙ × 2 · 10−16
erg cm2 s BIG uncertainty in the DM density ρ at 1pc from the GC: NFW or ...?
DM annihilation rate ∝ ρ2 is enhanced in the early universe: its products can
Primordial abundances are not safely known.
∼ 1000. 13.6 eV × ne ≪ uγ ionizes all H changing CMB anisotropies
Depends on unknown non-linear small-scale DM clustering. 1, 2 and 3 give comparable constraints at the PAMELA-level, σv ∼ 10−23 cm3/sec. 2 is stronger and robust and can be improved by PLANCK.
All at 3σ: region allowed by PAMELA e+ and FERMI e+ + e− vs bounds on: • FSR-γ from FERMI full sky, HESS Galactic Center, Ridge, Dwarf Spheroidals;
102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΜΜ, isothermal profile
FSRΓ PAMELA and FERMI Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4Μ, isothermal profile
FSRΓ PAMELA and FERMI Ν IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4e, isothermal profile
FSRΓ PAMELA and FERMI IC freezeout
e± excesses can be DM DM → 2µ, 4µ, 4e if ρ is isothermal
102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΜΜ, Einasto profile
GCΓ GRΓ FSRΓ GCradio PAMELA and FERMI Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4Μ, Einasto profile
GCΓ GRΓ FSRΓ GCradio PAMELA and FERMI Ν IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4e, Einasto profile
GCΓ GRΓ FSRΓ GCradio PAMELA and FERMI IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΜΜ, NFW profile
GCΓ GRΓ dSΓ FSRΓ GCradio GCVLT PAMELA and FERMI Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4Μ, NFW profile
GCΓ GRΓ dSΓ FSRΓ GCradio GCVLT PAMELA and FERMI Ν IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM 4e, NFW profile
GCΓ GRΓ dSΓ FSRΓ GCradio GCVLT PAMELA and FERMI IC freezeout
The problem is no longer only at small scales not tested by N-body simulations
L = 1 kpc at the GC (ok?) would relax NFW or Einasto down to isoT: DM annihilations outside the diffusion volume contribute to FSR, but not to IC:
1 10 2 3 4 5 7 1 10 0.3 3 L in kpc Σv with respect to NFW, L 4 kpc isoT NFW Einasto
Disavored by a) global fits of charged CR; b) abundances of CR with τ ∼ τdiff; c) FERMI sees γ away from the GC. d) realistic smooth growth of K(z). Can synchrotron dominate over IC? Only around the GC.
102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΤΤ, isothermal profile
GRΓ FSRΓ PAMELA and FERMI Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΤΤ, NFW profile
GCΓ GRΓ dSΓ FSRΓ GCradio GCVLT PAMELA and FERMI Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM ΤΤ, Einasto profile
GCΓ GRΓ FSRΓ GCradio PAMELA and FERMI Ν CMB IC freezeout
Too many τ → π0 → γ: FSR direct exclusion for any reasonable profile.
Non-leptonic channels give many FSR−γ and can at most be subdominant:
102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM bb, isothermal profile
GRΓ dSΓ FSRΓ PAMELA Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM WW, isothermal profile
GRΓ dSΓ FSRΓ PAMELA Ν CMB IC freezeout 102 103 104 1026 1024 1022 1020 DM mass in GeV Σv in cm3sec
DM DM hh, isothermal profile
GRΓ dSΓ FSRΓ PAMELA Ν IC freezeout
The SUSY wino or Minimal Dark Matter no longer can fit PAMELA .
DM decays
If instead DM decays with life-time τ, replace ρ2σv/2M2 → ρ1/Mτ:
102 103 104 1024 1025 1026 1027 DM mass in GeV DM lifetime Τ in sec
DM 4Μ, NFW profile
PAMELA and FERMI Ν ICΓ exGΓ FSRΓ 102 103 104 1024 1025 1026 1027 DM mass in GeV DM lifetime Τ in sec
DM ΜΜ, NFW profile
PAMELA and FERMI Ν ICΓ exGΓ FSRΓ 102 103 104 1024 1025 1026 1027 DM mass in GeV DM lifetime Τ in sec
DM ΤΤ, NFW profile
PAMELA and FERMI Ν ICΓ exGΓ FSRΓ
With DM decay PAMELA/FERMI are allowed for all DM density profiles
Weak bounds from BBN and CMB, again due to ρ2(t) → ρ1(t). The extra-galactic γ flux is significant: Φcosmo Φgalactic ∼ ρcosmoRcosmo ρ⊙R⊙ ∼ 1 and can be computed reliably: no de- pendence on small-scale DM clustering. The ‘exG-γ’ bound on FSR+IC is com- petitive, helped by FERMI who already extracted (?) the diffuse γ flux, a few times below the less bright sky.
101 1 10 102 103 108 107 106 Photon energy in GeV E2 dΓdE in GeVcm2sec sr
DM ΤΤ with M 6. TeV and Τ 5.4 1025 sec
FERMI FSR IC
1000 10000 3000 35 40 45 50 55 60 65 DM mass in GeV Χ2
DM decay
4Μ 4Τ ΜΜ ΤΤ WΜ WΤ
DM decays suggests M ∼ few TeV, which naturally implies the observed 5 ∼ ρDM ρb ∼ M mp
Tdec
3/2
e−M/Tdec if the DM density is due to a baryon-like asymmetry kept in thermal equilibrium by weak sphalerons down to Tdec ∼ 200 GeV. Possible if DM is a chiral fermion or is made of chiral fermions. The DM mass is M ∼ λv ∼ 2 TeV for λ ∼ 4π: strong dynamics a-la technicolor. GUT-suppressed dimension 6 4-fermion operators give τ ∼ M4
GUT/M5 ∼ 1026 s.
If the technicolor group is SU(2) with techni-q Q = (2, 0) under SU(2)L⊗U(1)Y
LL operator allows a slow DM → ℓ+ℓ−: no Π ≃ WL involved.
The PAMELA, FERMI-ATIC, HESS e± excesses attracted most attention. They could be due to astrophysics or to unexpected DM as follows: × 2e channel gave the ATIC peak, not the FERMI e+ + e− excess. × τ channels give too much γ. × W, Z, q, b, h, t channels can only fit PAMELA e+ and give too much γ.
quasi constant: i) Isothermal profile; ii) DM decays. DM predicts that the e+ fraction must grow. DM IC-γ must be in FERMI sky. Next: FERMI, PAMELA, AMS, PLANCK
Some theorists claim they see a quasi-spherical ‘FERMI haze’ excess:
180 90
20 GeV < E < 50 GeV residual (SFD)
180 90
45 90
Haze
0.1 1.0 10.0 100.0 1000.0 Photon Energy [GeV] 10-7 10-6 10-5 E2 dN/dE [GeV/cm2/s/sr]
FERMIons disagree [arXiv:1003.0002]