Review of dark matter searches and comments on CMO DM search. Stefano Scopel. International Workshop on Double Beta Decay Search, SNU, Seoul, October 1517 2009. Daejeon, 2426 september 2009.
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Review of dark matter searches and comments on CMO DM search
Stefano Scopel
International Workshop on Double Beta Decay Search, SNU, Seoul, October 1517 2009
Daejeon, 2426 september 2009
*
* For a review on cryogenic DM searches see tomorrow’s talk by Y.H. Kim
Ωdark matter~ 0.22
Evidence for Dark Matter
The concordance model
*
subdominant candidates – variety is common in Nature
→may be easier to detect
Weakly Interacting Massive Particles (WIMPs)
Particles with mass between a few GeV and a few TeV with cross sections of aproximately weak strength
The idea was introduced 35 years ago for massive neutrinos.Now neutrinos are ruled out, but there is no shortage of alternative WIMPs!
acronym “WIMP” eventually coined in mid ‘80
WIMP=Weakly Interacting Massive Particle
Kolb, Turner, The Early Universe
page 310
Pioneering work on direct DM searches @ Homestake mine in late ’80s:
however, today the sneutrino is not completely dead (rescaling due to relic density not applied to the signal at the time, see later)
few GeV<M<few TeV excluded both for neutrinos ad sneutrinos
*
most popular thermal WIMP candidates from particle physics (solve hierarchy problem: MW/MPl~ 1016)
DM candidate
conserved symmetry
Rparity
χ (neutralino)
Kparity
B(1)(KK photon)
Tparity
BH (heavy photon)
all thermal candidates, massive, with weaktype interactions (WIMPs)
x0
<σannv>int=∫<σannv>dx
xf
The thermal cosmological density of a WIMP X is given by
ΩXh2 ~ 1/<σannv>int
x0=M/T0
T0=present (CMB) temperature
xf=M/Tf
Tf=freezeout temperature
Xf>>1, X non relativistic at decoupling, low temp expansion for <σannv>: <σannv>~a+b/x
if σann~0.1 pbarn (weaktype interactions) → ΩX~0.11
New physics at the TeV scale (“WIMP Miracle”)
…+ cohannihilations with other particle(s)
close in mass + resonant annihilations
Weakly Interacting Massive Particles can be detected!
The same class of interactions that keeped WIMPS in thermal equilibrium in the early Universe could allow their detection today



g g
f f
W+W
ZZ
HH, hh, AA, hH, hA, HA, H+H
W+H, WH+
Zh, ZH, ZA
g g
f f
W+W
ZZ
HH, hh, AA, hH, hA, HA, H+H
W+H, WH+
Zh, ZH, ZA
n, n, g, p, e+, d


χ + Nχ + N
χ + χ
A couple of examples:
the neutralino and the KK photon
GUT unification of gauge couplings
~
~
~
~
4
3
IDEAL CANDIDATE FOR COLD DARK MATTER
stau coannihilation
Higgs funnel
focus point
[Feng, Machev, Moroi, Wilczek]
SUGRA
(a.k.a. CMSSM)
[Ellis, Olive, Santoso, Spanos]
neutralino density tends to be too large
Direct detection in SUGRA
[Ellis, Olive, Santoso, Spanos]
The NexttoMinimal MSSM (NMSSM)
2 Higgs (CPeven, CPodd)
MSSM+
1 neutralino dof
solves the μproblem, i.e. why μ~MEW
superpotential:
Higgs soft terms in the NMSSM:
NMSSM particle content:
The lightest neutralino:
CPeven Higgs:
Relic density and direct detection rate in NMSSM
[Cerdeño, Hugonie, LópezFogliani, Muñoz, Teixeira]
relic abundance
direct detection
Landau pole
W
χ,H lighter χ singlino
H1
Z
H2/2
tachyons
unphysical minima
M1=160 GeV, M2=320, Aλ=400 GeV, Ak=200 GeV, μ=130 GeV, tan β=5
(sizeable direct detection)
Effective MSSM: effective model at the EW scale with a few MSSM parameters which set the most relevant scales
SUGRAR=0.5
~
~
~
~
~
~
~
Can the neutralino be ?
Cosmological lower bound on mχ
M1<<M2,μ
[Bottino, Fornengo, Scopel, PRD68,043506]
scatter plot:
full calculation
upper bound on ΩCDMh2
curve: analytical
approximation for
minimal ΩCDMh2
(à la LeeWeinberg)
“funnel” at low mass
DAMA/NaI modulation region, likelyhood function values distant more than 4 σ from the null result (absence on modulation) hypothesis, Riv. N. Cim. 26 n. 1 (2003) 173,
astroph/0307403
Color code:
● Ωχh2 < 0.095
Ωχh2 > 0.095
Neutralino – nucleon cross section
tight correlation between relic abundance and χnucleon cross section:
The elastic cross section is bounded from below
The KK photon in Universal Extra Dimensions (UED)
[Appelquist, Cheng, Dobrescu, PRD67 (2000) 035002]
smaller
faster
if cohannihilating particle annihilates than LKP→ relic abundance
slower
larger
B(1)relic abundance
[Servant,Tait, NPB650,391;New J. Phys. 4,99; Kakizai & al., PRD71,123522; Kong, Matchev, JHEP0601,038]
both cases are possible : KK quarks and gluons vs. KK leptons
ΩB (1)h2=0.1
KK leptons
Δ≡fractional mass splitting
Δ≡(mq1mB1)/mB1
Typically, WIMPnucleon cross section for KKphotons is smaller than for a neutralino. For instance (Servant, Tait,NJP4(2002)99):
(assuming Higgsexchange dominance)
x
Belli, Cerulli, Fornengo, Scopel, PRD66,043503 (2002)
Upper limit on σscalar(nucleon) from CDMS and ZEPLIN: a scan of different models
A. Bottino, F. Donato, N. Fornengo and S. Scopel, PRD72 (2005) 083521
counterrotation
solid: CDMS, vesc=650 km/sec
long dashes: CDMS, vesc=450 km/sec
dots: ZEPLIN vesc=650 km/sec
PRD71,043516,2005
Annual modulation of WIMP direct detection in a nutshell
Expected rate: R=R0+Rm cos[ω(tt0)]
ω=2π/(1 year)
t0=2 june
Rm/R0~5÷10 % (few percent effect)
If N=# of events, assuming a 5% effect a 5 σ discovery requires:
5/100 X N > 5 X N½
modulation amplitude
poissonian fluctuation
⇒N > 10.000 events
N~ (incoming flux) x Ntargets x (cross section) x (exposition time)
expected rates: 0.1 events/kg/day
⇒a few x 100 kg x day required
hard to do: need large masses, low backgrounds, operational stability over long times…
The DAMA/Libra result (Bernabei et al., arXiv:0804.2741)
0.53 ton x year (0.82 ton x year combining previous data)
8.2 σ C.L. effect
A cos[ω (tt0)]
ω=2π/T0
DAMA disfavoured by other direct searches
small viable window with MWIMP≲ 10
From Savage et al., arXiv:0901.2713
KIMS spin independent limits (CsI)
ρD=0.3 GeV/c2/cm3
v0=220km/s
vesc=650km/s
Systematic uncertainty
Fitting, Quenching factor
energy resolution...
combined in quadrature
~ 15% higher than w/o syst.
Nuclear recoil of 127I
of DAMA signal region
ruled out
PRL 99, 091301 (2007)
no light target in CsI → in principle Na in DAMAmore sensitivefor mwimp≲ 20 GeV (but maybe not if channeling is important)
for mwimpo≳ 20 GeV KIMS limit does not depend on scaling law for cross sections
Quenching
Channeling effect in crystals
(Dobryshevsky, arXiv:0706.3095, Bernabei et al., arxiv:07100288)
critical angle:
C2~3, d=interatomic spacing
a0=0.529 Å (Bohr radius)
Channeling effect in crystals
(Dobryshevsky, arXiv:0706.3095, Bernabei et al., arxiv:07100288)
N.B.:
Channeling effect in crystals
A Bottino, F. Donato, N. Fornengo and S. Scopel, arXiv:0710.0553
no channeling
channeling
KIMS and annual modulation
[S.K.Kim talk, KIAS extended workshop 2009]
Many Dark matter searches on Earth:
DM searches in the world (running or projected)
scintillators
Ionization+heat (cryogenic)
dualphase TPC
Heat experiment (CUORICINO)
metastable bubbles
scintillator
Background wall reached (shielding is a background source itself): discriminating techniques needed
Exclusion plots on coherent WIMPnucleon cross section
Comment on CaMoO4 and Dark Matter direct detection
Byproduct of νless ββ search!
Some simple estimations:
B=10
100 kg year
1 keV threshold
B=1
B=0.1
B=1e2
CDMS 2008
B=1e3
B=1e4
B=0
Some simple estimations:
B=10
B=1
100 kg year
10 keV threshold
B=0.1
B=1e2
B=1e3
CDMS 2008
B=1e4
B=0
Some simple estimations:
B=10
5 kg year
1 keV threshold
B=1
B=0.1
B=1e2
CDMS 2008
B=1e3
B=1e4
B=0
Some simple estimations:
B=10
B=1
5 kg year
10 keV threshold
B=0.1
B=1e2
B=1e3
CDMS 2008
B=1e4
B=0
Other projected sensitivities and some theoretical predictions
Eth=10 keV
(5 and 100 kg year)
CaMoO4
CDMS 2008
SuperCDMS 25kg
XENON10 2007
Bottino et al
XENON100 6000 kgd
Eth=1 keV
(5 and 100 kg year)
Trotta et al
CMSSM, Ellis et al
Ellis et al
CMSSM, Markov chain Trotta et al
Effective MSSM, Bottino et al
Historical remark
Name “neutrino” proposedby Enrico Fermi in the international congress organized in Rome from 11 to 17october 1931
ino=suffix in italian for small (ex: neutrino=small neutron, cuoricino=small cuore)
10
9
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1
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5
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Besides E. Fermi(1) in this picture: R. Millikan(2), M. Curie(3), G. Marconi(4), N. Bohr(5), A. Sommerfeld(6), A. H. Compton(7), P. Ehrenfest(8), W. Heisenberg(9), E. Majorana(10)