The Dark Matter Hunter GuideS 2 HSS jHj S 4 S4 102 103 10- 46 10- 45 10- 44 10- 43 DMmassin GeV s SI...
Transcript of The Dark Matter Hunter GuideS 2 HSS jHj S 4 S4 102 103 10- 46 10- 45 10- 44 10- 43 DMmassin GeV s SI...
The Dark Matter Hunter Guide
Testing weak scale DM
from the sky from the underworld from CERN
DM
DM
SM
SM
indirect Hand cosmology?L
?
DM
SM
DM
SM
direct
?
SM
SM
DM
DM
collider
?
DM at colliders
DM at colliders, what signal?
Safe concrete expectations are well-known and trivial:
• DM is probably stable thanks to a Z2 symmetry: DM produced in pairs.
• DM behaves like ν: DM carries away missing transverse momentum 6pT .
• Maybe DM comes alone giving /pT j and /pTγ from initial state radiation.
• Maybe DM comes with other particles giving better signals.
It would be wise to stop here.
Anti-pedagogical presentation
The rest is a list of disconnected speculations and their signals
DM
...
Ultra-light
Particle
Ultra-heavy
...
...
Asymmetric
Rehating
Thermal relic
Freeze-in
Freeze-out & decay
...
...
Scalar singlet
Kalzua-Klein
SUSY
Minimal DM
Mirror world
...
...
Gravitino
Q-balls
Neutralino
Sneutrino
Axino
...
...
Wino
Bino
Higgsino
...
? ? ? ? ?
Like reading a phone book/cleaning stains from a jaguar...
Politically Correct Dark Matter
According to the ideology that dominated past decades, the Higgs mass has a
hierarchy problem solved by many new particles at the weak scale.
The most popular solutions are the supersymmetric sparticles. SUSY ruins B,L
conservations, so theorists add a new Z2 symmetry (R-parity, KK parity):
SM→ SM new→ −new
which makes the lightest new particle stable: DM candidate if neutral!
WIMP miracle: the thermal abundance of a weak particle can reproduce ΩDM!!
“Neutralino” is often used as a synonymous of “Dark Matter”!!!
Big signals! DM is the last step of a decay chain that starts with g/q production
g → gq → g`χ→ g``N
Many authors proposed kinematical variables to reconstruct the masses.
But next LHC was turned on and nothing like this has been seen so far.
Dark Matter in the CMSSM
ΩDM suggested neutralino annihilations via sleptons up to a few crazy regions.
The ‘bulk’ region got excluded leaving the tail, the nose: only special mech-
anisms can give ΩDM: ˜ co-annihilations, H,A resonance, h,H,A at large
tanβ, t co-annihilations, well-tempered B/H (excluded by Xenon for µ > 0), h
resonance (excluded by LHC, M3 > 3mh). Like dissecting the spherical cow.
Well-tempered neutralinos
If M <∼ TeV winos and higgsinos annihilate too much, binos annihilate too little.Like in the 3 bear fable, the observed thermal ΩDM is obtained by mixing them.
Wino/bino (M1 ' M2) is not detectable. Wino/higgsino (M2 ' µ) is lessplausible. Wino/bino (M1 ' |µ|, green strip) has been disfavoured by Xenon(dark region) if µ > 0; cancellations are possible for µ < 0
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M1
inGe
V
well tempered binohiggsino, tan Β = 10
mDM =m
h 2m
DM =mZ 2
Stop co-annihilation
A light stop can lead to correct thermal ΩDM if ∆M = Mt −MDM ≈ 30 GeV
σvcosmo =3
8e−2∆M/T
︸ ︷︷ ︸co−annihilation
× 7 g43
216πm2t1︸ ︷︷ ︸
σ(tt∗→gg)v
≈ 2.3× 10−26 cm3s−1
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10
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30
40
50
Neutralino DM mass MDM in GeV
DM
=m
t 1-
MD
Min
GeV
CMS razorhadronic onlyour analysis
DMlin
e
t 1®
NbΝ
t 1®
Nt
t 1®
Nc
t 1®
NbW
t1
LSP
150 200 250 300 350 400 450 5000
100
200
300
400
Lightest stop mass in GeV
Neu
tral
ino
mas
sin
GeV
Good sensitivity at LHC thanks to big σ(pp→ t+ t∗+ ISR jets) from QCD.
SUSY, SUSY, SUSY
One-letter extensions of the MSSM:
AMSSM, BMSSM, CMSSM, DMSSM, EMSSM, FMSSM, GMSSM, HMSSM,
IMSSM, KMSSM, MMSSM, NMSSM, OMSSM, PMSSM, QMSSM,
RMSSM, SMSSM, TMSSM, UMSSM, VMSSM, XMSSM, YMSSM, ZMSSM
According to google, the JMSSM and the LMSSM have not yet been proposed.
SUSY covers a lot of possibilities... The LSP could decay into the graviton.
Charged tracks and secondary vertices if the LSP is charged or coloured and τ
is slow enough. If very slow, LSP could decay while the beam is off...
Etc etc... Furthermore, natural scenarios alternative to SUSY are sometimes
considered, especially universal extra dimensions and Little Higgs.
Etc etc... In models with a light dark sector, long dark decay chains can give
things like ‘muon jets’ when/if dark particles decay into light SM particles
Is nature natural?
The good possibility is in trouble
Present data indicate do not confirm the usual naturalness ideology
The bad possibility is that the Higgs is light due to ant**pic reasons. Then,
one would expect that H is the only light scalar, so weak-scale DM must be a
fermion. This lead to consider ‘split SUSY’ i.e. neutralino/wino/higgsino DM.
The ugly possibility is that quadratic divergences should be ignored. Then
the SM satisfies ‘finite naturalness’. To preserve this property, new physics
motivated by data, such as DM, must be not much above the weak scale.
Consider: scalar/fermion DM and DM with/without SM gauge interactions.
Minimal Dark MatterAdd only one electroweak multiplet containing a neutral DM particle.Assume that it has only gauge interactions. In one case it is automatic: afermion weak 5-plet cannot couple to SM particles, so DM stability arises asan accidental symmetry, just like baryon number within the SM.
The neutral component gets lighter by ≈ 166 MeV. Compute annihilation crosssections and predict the DM mass: TeV. Finite naturalness arises at two loops.
Quantum numbers DM could DM mass mDM± −mDM Finite naturalness σSI inSU(2)L U(1)Y Spin decay into in TeV in MeV bound in TeV 10−46 cm2
2 1/2 0 EL 0.54 350 0.4×√
∆ (2.3± 0.3) 10−2
2 1/2 1/2 EH 1.1 341 1.9×√
∆ (2.5± 0.8) 10−2
3 0 0 HH∗ 2.0→ 2.5 166 0.22×√
∆ 0.60± 0.043 0 1/2 LH 2.4→ 2.7 166 1.0×
√∆ 0.60± 0.04
3 1 0 HH,LL 1.6→ ? 540 0.22×√
∆ 0.06± 0.023 1 1/2 LH 1.9→ ? 526 1.0×
√∆ 0.06± 0.02
4 1/2 0 HHH∗ 2.4→ ? 353 0.14×√
∆ 1.7± 0.14 1/2 1/2 (LHH∗) 2.4→ ? 347 0.6×
√∆ 1.7± 0.1
4 3/2 0 HHH 2.9→ ? 729 0.14×√
∆ 0.08± 0.044 3/2 1/2 (LHH) 2.6→ ? 712 0.6×
√∆ 0.08± 0.04
5 0 0 (HHH∗H∗) 5.0→ 9.4 166 0.10×√
∆ 5.4± 0.45 0 1/2 stable 4.4→ 10 166 0.4×
√∆ 5.4± 0.4
7 0 0 stable 8→ 25 166 0.06×√
∆ 22± 2
Sommerfeld correctionsNon-relativistic DM DM annihilations are enhanced if M >∼MW/α
2F
3F
3S
5F
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DM mass in TeV
WD
Mh2
Wino/MDM searches
Γ(DM± → DM0π±) = (n2 − 1)/44 cm = 0.977 Γ(DM±) ∆M = 166 MeVCo
llision
Detector1 cm
B Å Tesla
Slow DM+ straigh track RelativisticcurvedΠ+ track
Trigger on initial state radiation and missing energy, LHC better than LEP
Phenomenology: EWinos
Heavy Higgsinos:
Bino LSP : c±c0 → Wh+MET c+c- → WW+MET
Wino LSP: Dm~170 MeV → 10cm stubs (trig. on ISR+MET )
Singlet Scalar DM
L = LSM +(∂µS)2
2− m
2S
2S2 − λHSS2|H|2 − λS
4S4
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Σ SIin
cm2
scalar DM singlet
Excluded by Xenon 2012
DM thermal abundance
Finite naturalness
D =1
D »100
Λ =1
σSI =λ2HSm
4Nf
2
πM2M4h
δm2 = −2λ2HS
(4π)2M2(ln
M2
µ2− 1) < ∆×M2
h
Singlet Fermion DM
L = LSM +(∂µS)2
2+ ψi/∂ψ−m
2S
2S2− λS
4S4−λHSS2|H|2 +
y
2Sψψ+
Mψ
2ψψ+ h.c.
Communicate via S. Thermal annihilations are p-wave, so σSI is often too large.
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Σ SIinc
m2
Fermion DM singlet HmS=300 GeVL
Excluded by Xenon 2012D=1
D=100
Finite Naturalness
DM thermal
abundance
σSI =y2 sin2 2α
8π
m4Nf
2
v2
(1
M2h
− 1
M2S
)2
δm2 =6y2 sin2α
(4π)2M2(ln
M2
µ2− 1
3)
DM and Higgs decays
Consider scalar (S) or fermion (F ) or vector (V ) DM coupled to the Higgs as
rS2m2
S
VhSS + rf
mf
Vhff + rV
2m2V
VhVµVµ
where r = 1 if DM gets mass only from 〈h〉 = V . Invisible Higgs decays are agreat signal for M < Mh/2: BRinv<∼19− 28% at 95% CL constrains σSI
0.0 0.2 0.4 0.6 0.8 1.0
0
5
10
15
20
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DΧ
2
SM + BRinv
SM+BRinv+
+BRgg+BRΓΓ
1Σ
2Σ
3Σ
4ΣXenon100
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Spin
-In
dep
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tΣ
SIin
pb
scalar
fermion
vector
Effective operator description?
Assume that the physics that couples DM to quarks is so heavy that can be
integrated out leaving effective operators of the form
1
Λ2[ΨDMγµΨDM][ΨSMγ
µΨSM]
General framework where everything is computed in terms of Λ and M , e.g.
ΩDM
ΩexpDM
=(Λ/700 GeV)4
(M/150 GeV)2σSI ≈ 5 10−39 cm2
(M
mN +M
)2 (700 GeV
Λ
)4
CMS and ATLAS j /ET and γ /ET searches imply Λ > 700 GeV for M Λ.
For any collider the limit will be Λ √s. So the effective approximation is not
valid. What LHC would really see is the particle that mediates the operator.
Detectable Dark Matter below a TeV?
DM above a TeV is too heavy for LHC and for δm2h. DM below a TeV with
weak gauge interactions annihilates too much leaving a too low ΩDM, unless:
• Extra solution at M < MW such that too large σ(DM DM → W+W−) is
kinematically suppressed. Not fully excluded by LEP. E.g. ‘inert doublet’
• Mix interacting (M v) with singlets (M → 0): get any intermediate M .
• DM as singlet + extra coupling e.g. binoDM-lepton-slepton Yukawa in SUSY
works if sleptons are around or below the LEP bound. Small extra couplings
can be resonantly enhanced, e.g. DM DM → A→ bb in SUSY if MA = 2M .
DM at colliders: summary
Simplest scenario: only DM is produced, an initial state jet allows to see
6pT + soft jet
Plausible scenario: DM could be the lightest of a new set of particles (like
in SUSY). LHC dominantly produces heavier colored particles (gluino, squarks)
that decay down to DM. The signal depends a lot on the decay chains
6pT + hard jets or leptons or...
Possible scenario: the lightest sparticle is charged or colored and decays into
“gravitinos” or “axino” DM with life time τ >∼m
charged tracks, decays after the collisions
etc etc etc but nothing seen in data so far
Direct DM detection
Direct DM detection: key parameter
σSI = spin-independent DM-nucleon cross section
allows to compare experiments: DM/nucleus cross section σN = A2σSI.
DM
N
Z
N
DM
tree, vector
ΣSI »Α2 mN
2
MZ4
DM
N
h
N
DM
tree, scalar
ΣSI »Α2 mN
4
Mh6
DM
N
DM
N
W W
DM±
N
loop
ΣSI »Α4 mN
4
MW6
The vector effect vanishes if DM is real (e.g. a Majorana fermion).
Experimental progress
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vector: Σ » Α2mN2 MZ
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loop: Σ » Α4mN4 H4ΠL2MW
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atmospheric Ν background
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incm
2fo
rMD
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History of direct DM searches
DA
MA
Xen
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MS
DM must be neutral under the γ, g and almost neutral under the Z
‘Anomaly-free’ Dark Matter
Ignoring experiments that claim ‘anomalous’ results, this is the present status:
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ΣSI
incm
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Spin-independent DM detection: bounds at 90%CL
CDMS2009
Xenon2011
Xenon2012
[Below a few GeV is ≈ terra incognita]
Sub GeV DM
When nuclear recoil ER ∼ EDM(mN/M) becomes too small, EDM = M2 v
2 ∼50 eV(M/100 MeV) can lead to (a) e ionization; (b) e excitation; (c) molecular
dissociation giving individual e or γ or ion or phonons. First bound: 4
FDM=Ha meêqL2
FDM=Ha meêqLFDM=Ha meêqL2
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se@cm
2 DExcluded byXENON10data
1electron
2electrons3electrons
Hidden-Photonmodels freeze-in
FIG. 3: 90% CL exclusion limits on e for candidates witha DM form-factor FDM(q) of (↵me/q) (red/lower line), cor-responding to DM with an electric dipole moment, and(↵me/q)2 (blue/upper line), corresponding to DM scatteringthrough a very light mediator. Dashed lines and bands are asin Fig. 2. The pale blue region shows the previously allowedparameter space for DM coupled through a very light hiddenphoton (FDM = (↵me/q)2), with the gray strip indicating the“freeze-in” region (taken from [2]).
models in which the DM candidate is a fermion coupledto the visible sector through a kinetically mixed “hid-den photon” with O(MeV-GeV) mass, and satisfying allpreviously known constraints (from [2]; see also [3] [25]).
Fig. 3 shows the exclusion limits in the mDM-e planefor DM candidates whose interaction with electrons isenhanced at small momentum-transfers by a DM form-factor, FDM. The red (lower) curves correspond toFDM = (↵me/q), or DM scattering through an elec-tric dipole moment, and the blue (upper) curves toFDM = (↵me/q)2, or DM scattering though a very light( keV) scalar or vector mediator. Bounds set by 1-,2-, and 3-electron rates are shown by dashed lines, andthe central limits by dark lines. The bands illustratethe theoretical uncertainty. Both form-factors suppressthe relative rate of events with larger energy deposition,and so reduce the fraction (and hence the importance) ofevents containing multiple electrons. The pale blue re-gion shows the parameter space for DM coupled througha very light hidden-photon mediator, and satisfying allpreviously known constraints, with the gray strip show-ing where the correct abundance is achieved through“freeze-in” (from [2]). These regions should be comparedto the blue exclusion curve.DISCUSSION. The results above demonstrate, for thefirst time, the ability of direct detection experiments toprobe DM masses far below a GeV. It is encouraging thatwith only 15 kg-days of data, and no attempt to controlsingle-electron backgrounds, the XENON10 experimentplaces meaningful bounds down to masses of a few MeV.
It should be emphasized that this analysis lacks theability to distinguish signal from background. One
promising method is the expected annual modulation ofthe signal. As discussed in [2], additional discriminationmay be possible via the collection of individual photons,phonons [24], or ions, although at present such technolo-gies have yet to be established.
Independently, this type of search could be signifi-cantly improved with a better understanding of few-electron backgrounds. A quantitative background es-timate was not made in [10], making background sub-traction impossible. Single-electron ionization signalshave been studied, and potential causes discussed, byXENON10 [9], ZEPLIN-II [7], and ZEPLIN-III [8]. Pos-sible sources include photo-dissociation of negativelycharged impurities, spontaneous emission of electronsthat have become trapped in the potential barrier at theliquid-gas interface, and field emission in the region ofthe cathode. The former two processes would not beexpected to produce true two- or three-electron events,although single electron events may overlap in time, giv-ing the appearance of an isolated, double-electron event.With a dedicated study, these backgrounds could bequantitatively estimated and reduced.
With larger targets and longer exposure times, ongo-ing and upcoming direct detection experiments such asXENON100, XENON1T, LUX, and CDMS, should beable to improve on the sensitivity reported here. Suchimprovements may require optimizations of the trigger-ing thresholds, and will strongly benefit from additionalstudies of the backgrounds.
Acknowledgements
R.E. acknowledges support from NSF grant PHY-0969739. J.M. is supported by a Simons PostdoctoralFellowship. T.V. is supported in part by a grant fromthe Israel Science Foundation, the US-Israel BinationalScience Foundation and the EU-FP7 Marie Curie, CIGfellowship.
[email protected]† [email protected]‡ [email protected]§ [email protected]¶ [email protected]
[1] G. Bertone, D. Hooper and J. Silk, Phys. Rept. 405(2005) 279 [arXiv:hep-ph/0404175].
[2] R. Essig, J. Mardon and T. Volansky, Phys. Rev. D 85(2012) 076007 [arXiv:1108.5383].
[3] T. Lin, H. B. Yu and K. M. Zurek, [arXiv:1111.0293].[4] J. L. Feng and J. Kumar, Phys. Rev. Lett. 101 (2008)
231301 [arXiv:0803.4196].[5] X. Chu, T. Hambye and M. H. G. Tytgat,
[arXiv:1112.0493].[6] P. W. Graham, D. E. Kaplan, S. Rajendran and
M. T. Walters, [arXiv:1203.2531].[7] B. Edwards et al., Astropart. Phys. 30 (2008) 54
[arXiv:0708.0768].
Ultra-light DM
If DM is so light that its scatterings are too soft even for atomic physics, DM can
still be detected via quantum interference! Experimentalists are able of splitting
the wave functions of nucleons or atoms by a small distance (nm to cm).
Quantum interference is lost if one of them interacts with DM. Experiments
are done with a few atoms for a few seconds, so the bound is NA weaker 6
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mDM HeVL
sHcm
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AGIS
XQC
Heating+Halo
Ly-a
CMB+
LSS
200 km HrocketL
30 km HballoonLSea level
Hen0
C70
PFNS10
OTIMA-4
OTIMA-6
OTIMA-8
AGIS
Nanosphere
SIMP
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mDM HeVLFIG. 5. The sensitivity of several existing and proposed superposition experiments to the spin-independentnucleon scattering cross-section of dark matter, compared with existing constraints. (a) Gray shaded regions arerobustly excluded by the X-ray Quantum Calorimetry experiment (“XQC” [9]) and galactic heating and halo stability arguments(“Heating+Halo” [29]). Hatched regions are incompatible with thermal DM models due to observations of the cosmic microwavebackground with large scale structure data (“CMB+LSS” [30]) and the Lyman-↵ forest (“Ly-↵” [31]). Solid colored lines boundregions where DM would cause decoherence in three proposed experiments: a satellite-based atom interferometer (“AGIS” [24]),optically-trapped silicon nanospheres (“Nanosphere” [19]), and the OTIMA interferometer with clusters of gold of mass 106
amu (“OTIMA-6” [17]). A successful AGIS satellite would set new exclusion limits on DM where its sensitivity dips below thehalo heating/stability bound for mDM 1 keV. On the other hand, the OTIMA and nanosphere experiments would be shieldedfrom DM by the atmosphere if operated at sea level, so exclusion regions illustrate the sensitivity at an altitude of 200 km. Thedarker regions bordered by colored dashed lines indicates where the coherent phase shift due to the DM wind could be observedwithout being overwhelmed by decoherence. (b) On top of the existing exclusions (now black dotted lines), the colored linesgive the lower limits on the sensitivities of existing interferometers with helium atoms (“He” [32]), cold neutrons (“n0” [33]),fullerenes (“C70” [34]), and the large organic molecule C60[C12F25]10 (“PFNS10” [18]). Also shown are sensitivities for theAGIS satellite, the OTIMA interferometer with three choices of gold cluster mass (104, 106, and 108 amu, although the last isnot feasible for an Earth-bound experiment), and the nanosphere experiment. The border is defined by an e-fold suppressionof the interference fringes: = 1e. Sensitivity increases dramatically for larger masses. When operated within the Earth’satmosphere, there is a potential to detect DM only where the sensitivity dips below the dashed-dotted line corresponding tothe degree of shielding at the relevant altitudes. None of the existing experiments do so. For reverence, strongly interactingmassive particle (“SIMP” [35]) models lie in the black band.
the Earth’s surface at about 10−27cm2. This can be cir-cumvented by placing the experiment on a high-altitudeballoon (∼30 km altitude; ∼10−25cm2), a sounding rocket(∼200 km altitude; ∼10−18cm2), or on a satellite. I donot know if anyone has studied the possibility of produc-ing macroscopic quantum superpositions on a balloon orrocket, but spaceborne experiments are both feasible andcompelling for independent reasons [17, 38, 39].
Figure 5 shows the potential reach of several existingmatter interferometers [18, 32–34] in the absence of atmo-spheric shielding. The separation vector x is assumedto point into the DM wind. The e↵ects of rotating xwith respect to the wind are order unity and are depicted
in figure 4. Modern experiments often use multiple grat-ings with many slits to overcome diculties with beamcoherence and tiny de Broglie wavelengths [40, 41], sothe matter is not described by a simple superpositionof two spatially separated wavepackets. But the interfer-ometers still require good coherence over distances whichspan multiple slits, so it is reasonable to estimate theirsensitivity by taking x to be the period of the relevantgrating. (Only the results for small mDM will depend onthe choice of x; for larger masses, which are in the shortwavelength limit, any scattering event results in completedecoherence independent of the spatial separation.)
To demonstrate the potential of future experiments to
Indirect DM detection
Indirect signals of Dark Matter
DM DM annihilations in our galaxy might give detectable γ, e+, p, d.
Measurements of charged cosmic rays
p e+/(e+ + e−) e+ + e−
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Explaining the e+ excess
Due to astrophysics? Maybe pulsars or primary e+? Due to DM?
e+ spectrum reproduced if DM annihilates into leptons with σv ∼ 103σvcosmo
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Posi
tron
frac
tion
DM DM ® VV ® 4Μ with M = 1 TeV
background?
AMS 2013
PAMELA 2009
1000 10000300 300020
30
40
50
60
DM mass in GeV
Χ2
DM annihilation fit to e+ after AMS
e+e-
Μ+ Μ-Τ+Τ-4e
4Μ
4Τ
qW
Z
b
t
h
AMS hint of a flattening favours M ∼ TeV
Not seen in p: leptonic modes again. Not seen in γ: needs quasi-constant ρ(r).
Explaining the e± excesses
Hints of drops in e+/(e+ + e−) and in e+ + e− but at different energies
ææ
ææ
æææ
ææ
æ
ææææææææ
æææææ
æææææ æ æ æ æ æ æ æ æ æ æ ææ
æ æ
à
à
à
à
à
à
à
à
ì
ì
ìì
ìì
ì
ì
ì
ò
ò
òò
ò ò
ò
ò ò ò
ò
ò
ò
ò
ò
ò
ò
ò
ò
ò
ò
10 102 103 104
0.01
0.003
0.03
Energy in GeV
E3
He-+
e+
LGeV
2cm
2se
c
DM DM ® VV ® 4Μ with M = 1 TeV
FERMI
HESS08
HESS09
1000 10000300 300055
60
65
70
75
80
DM mass in GeV
Χ2
DM annihilation fit to e+ and e
++e- after AMS, FERMI
4e
4Μ
4ΤΜ+ Μ- Τ+Τ-
AMS can clarify measuring very precisely the e+ + e− spectrum
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arXiv:1012.4515
Dark Matter: what it is?
Why DM should be a weak scale particle, if new physics must not be there?
Dark Matter: how heavy?
DM exists, but so far we have seen only its gravity
Decades of theoretical work restricted the DM mass to a range of 100 orders
of magnitude. We do not even know if DM is astro-physics or particle physics
10-30 10-20 10-10 1 1010 1020 1030eV
10-10 1 1010 1020 1030 1040kg
Solar mass
Planck scale
weak scaleTnow
Primordialblack hole
Ultra-light scalars, axion Νs
thermalparticles
DM as ultra-heavy objects (MACHO)?
Dead stars, planets, Black Holes... must be either non-baryonic (mirror world?)
or made before BBN (primordial BH?). DM ‘particles’ are lighter than small
galaxies so M < 105M where M = 2 1033 g is the solar mass. Microlensing
surveys imply that MACHO Milky Way fraction is < 20% around M ∼M.
10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 100%
10%
20%
30%
40%
50%
60%
MACHO mass M in solar masses
fracti
onfo
fhalo
mass
cons
isting
ofM
ACHO
s
MACHO
coll, 2000
EROS coll., 2006
95% excluded
OGLE-3
2011
95% excl.
EROS-1 + MACHO, 1998
95% excl
DM as Primordial Black Holes (PBH)?
PBH are not predicted by standard cosmology because primordial fluctuationshave small amplitude δk ∼ 10−5 1. Allowed mass range:
10−13M <∼ M <∼ 10−7MA BH cannot be too light be-
cause it emits photons evapo-
rating in a time ∼ G2NM
3.
Non-observation of micro-
lensing nor of X-ray emission
from matter falling into BH.
1015 1020 1025 1030 1035 1040 1045 105010-4
10-3
10-2
10-1
110-20 10-15 10-10 10-5 1 105 1010 1015
MACHO or PBH mass M in grams
fracti
onfo
fDM
MACHO or PBH mass M in solar masses
PBH
evap
orated
byno
w
evap
oratio
ntod
ay
X-raysspoilCMB
allowedPBH DMwindow
GRBlens
microlensing
accumulationin GC
disfavored bygalaxy sizes
binaries
radiolensing
Axions as ultra-light scalar DM
Practical summary: the axion a is a well-motivated particle with
ma =mπfπ/fa√
(1 +mu/md)(1 +md/mu +md/ms)≈ 0.6 meV
1010 GeV
fa
gaγγ =αem
2πfa(
∑q2
T2− 2
3
4 +mu/md +mu/ms
1 +mu/md +mu/ms)
ΩDM ≈√ma
eV
(a∗
1011 GeV
)2
Axion searches
shining-through-wall
a*=0.01 fa
a*=0.1 fa
a*= fa
10-8 10-6 10-4 10-2 1 102 104
10-20
10-18
10-16
10-14
10-12
10-10
10-8
10-6
axion mass in eV
axio
nco
uplin
gg a
ΓΓin
1G
eV
Τa =
TUniverse
Bound froma ®
ΓΓ
axion
0
models
83
Supernovae, stars and helioscopes
DM a ® Γ
conversion
ADMXADMX near future:Sensitivity with dilution-refrigerator cooling"
10-10
10-16
10-15
10-14
10-13
1 10 100 1000
1 10 100
Axio
n C
oupl
ing
|gaaa |
(GeV
-1)
Axion Mass (µeV)
ADMX Achieved and Projected Sensitivity
Cavity Frequency (GHz)
"Hadronic" Coupling
Minimum Coupling
Axion Co
ld Dark
Matter
ADMX Published
Limits
2013Target
2014Target
2015Target
10 GHz R&D
500 MHz R&D
Non RF-cavity TechniquesTo
o Mu
ch D
ark
Matt
er
Supernova Bound
Dilution refrigerator cooled detectors allow scanning at or below “DFSZ” sensitivity at fractional dark-matter halo density."This defines a definitive QCD dark-matter axion search!
IDM23jul12 LJR 22
New ideas for axion detection
DM axions passing through a magnetic
fields make an electric field with ω = ma. If
a metallic surface is also present, an electro-
magnetic wave is emitted perpendicularly to
it. Using a spherical surface, such waves
can focused in the centre, and detected.
Detectors sensitive to powers of 10−25 W
would start to probe the axion strip for all
masses down to ≈ 1/m. [1212.2970]
EBL
xionOptical
CAST+Sumico
ALPS
Haloscopes
10-21W
10-23W
10-25W
1 Hz
10-2Hz
10-4Hz
Standard ALP CDM
Suppressed Therm
al mass
Axionmodels
-9 -6 -3 0 3-19
-16
-13
-10
-7
Log10 mf @eVD
Log 10g@Ge
V-1 D
Figure 3: The allowed parameter space for axion-like particle dark matter (ALP CDM) is shownin various shades of red (for details see Ref. [3]). The various colored regions are excluded byexperiments and astrophysical observations that do not require HP dark matter (for reviewssee [1,2]). The lines correspond to the sensitivity of a dish antenna (1m2 dish in a 5 T magneticfield) with a detector sensitive to 1021, 1023 and 1025 W (green, from top to bottom) and1, 0.01 and 104 photons per second (blue, from top to bottom).
(2.24) we therefore find,
g, sens =3.6 108
GeV
0@ 5 Tq
h|B|||2i
1A
Pdet
1023 W
12 m
eV
0.3 GeV/cm3
DM,halo
12
1 m2
Adish
12
,
(3.4)and
g, sens =4.6 106
GeV
0@ 5 Tq
h|B|||2i
1A
R,det
1 Hz
12 m
eV
32
0.3 GeV/cm3
DM,halo
12
1 m2
Adish
12
, (3.5)
where h|B|||2i is the average value of the magnetic field squared parallel to the antenna dish.
10
Axions with f ∼MPl could be detected as oscillating neutron electric dipole or
by angular momentum loss of rotating black holes due to axion emission...
Axion DM already observed!?
Three big claims from Sikivie and others:
1) Axions interact form a coherent Bose-Einstein condensate;
2) This leads to caustics in the DM galactic densities ρ(r) at special radii;
3) Such caustics are supported by data.
Step 1) is based on interactions rates linear in the axion couplings, either
gravity or a small quartic. This is derived as a consequence of the large axion
occupation numbers, such that short-time axion scatterings would not conserve
energy. I don’t understand what is the sense of this.
Axion coherence should hold at most for times t ∼ 1/maβ2.
Conclusions / last slide
1) DM exists.
2) We no longer believe we know where to look for it.
3) LHC starts now to be sensitive to electroweak multiplets.
4) Watch axions