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Lars Bergström
Department of Physics
Stockholm University
[email protected]
SUSY 2005, Durham, England
July 21, 2005
J. Tonry et al
D.N. Spergel et al., Astrophys.J.Suppl.148:213,2003
SDSS (and
2dFGRS), 2005
U. Seljak & al astro-ph/0407372
Helium maybe
Basic facts:
Wi 
 crit
3H 02mPl
 crit 
 1.88h 2  1029 g / cm 3
100 kms 1 Mpc 1
Observations give 0.6 < h < 0.8
Big Bang nucleosynthesis (deuterium
abundance) and cosmic microwave
background (WMAP) determine baryon
contribution WBh2  0.023, so WB  0.04
Wlum  (4 ± 2) . 10-3 (stars, gas, dust) =>
baryonic dark matter has to exist (maybe as
warm intergalactic gas?)
But, now we know that WM > 0.2, so there has
to exist non-baryonic dark matter!
Lithium underabundant?
Fields & Sarkar, 2004
Cold Dark Matter
• Part of the “Concordance Model”, WCDM  0.3, WL  0.7
• Gives excellent description of CMB, large scale structure, Lya forest, gravitational lensing, supernova distances …
• If consisting of particles, may be related to electroweak mass
scale: weak cross section, non-dissipative Weakly Interacting
Massive Particles (WIMPs). Potentially detectable, directly or
• May or may not describe small-scale structure in galaxies:
Controversial issue, but alternatives (self-interacting DM,
warm DM, self-annihilating DM) seem worse. Probably nonlinear astrophysical feedback processes are acting (bar
formation, tidal effects, mergers, supernova winds, …). This
is a crucial problem of great importance for dark matter
detection rates.
Good particle physics candidates for Cold Dark Matter:
Independent motivation from particle physics
• Axions (introduced to solve strong CP problem)
• Weakly Interacting Massive Particles (WIMPs,
3 GeV < mX < 50 TeV), thermal relics from Big
Bang: Supersymmetric neutralino
Axino, gravitino
Kaluza-Klein states
Heavy neutrino-like particles
Mirror particles
”Little Higgs”
plus hundreds more in literature…
• Non-thermal (maybe superheavy) relics:
wimpzillas, cryptons, …
miracle”: for
typical gauge
couplings and
masses of order
the electroweak
scale, Wwimph2 
0.1 (within factor
of 10 or so)
mSUGRA or CMSSM: simplest (and most
constrained) model for supersymmetric dark
H. Baer, A. Belyaev, T. Krupovnickas,
J. O’Farrill, JCAP 0408:005,2004
R-parity conservation, radiative electroweak
symmetry breaking
Free parameters (set at GUT scale): m0, m1/2,
tan b, A0, sign(m)
4 main regions where neutralino fulfills
WMAP relic density:
• bulk region (low m0 and m1/2)
• stau coannihilation region m  mstau
• hyperbolic branch/focus point (m0 >> m1/2)
• funnel region (mA,H  2m)
• (5th region? h pole region, large mt ?)
However, general MSSM model versions give more freedom. At least 3 additional
parameters: m, At, Ab (and perhaps several more…)
In particular: special models like split supersymmetry, models with CP violation, etc.
No time to cover:
• Models with additional singlet superfield (NMSSM) (Example:
Cerdeño & al.)
• Models with large |A0| (Example: Häfliger, Stark & al., Parallel
Session; PS)
• Models based on supergravity with general relation beteween
gaugino masses (Example: Baek, Cerdeño & al PS; Belanger et al.)
• Models with gravitino as LSP (many contributions in PS)
• Models based on supergravity with non-universal Higgs masses
(Example: Baer & al; Huitu et al)
• Models with supersymmetric version of axion (”axino”) (Example:
• Models with cosmological SUSY breaking (Example: Banks, talk)
• Orbifold and KKLT scenarios (Example: Bertone & al.; Schmidt,
PS; Falkowski et al)
• Models with CP violating phases (Example: Balázs & al; Sato PS;
Nihei PS; Allahverdi & Drees)
• etc, etc, ….
A. Belyaev, hep-ph/0410385
P. Gondolo, J. Edsjö, L.B.,
P. Ullio, Mia Schelke and
E. A. Baltz, JCAP
0407:008, 2004 [astroph/0406204 ]
”Neutralino dark matter made easy” Can be freely dowloaded from
Release 4.1: includes
coannihilations &
interface to Isasugra
Other package: MicrOMEGAs, G. Bélanger, F. Boudjema,
A. Pukhov and A. Semenov,
To match WMAP precision on WCDMh2, high-precision relic density
calculations are needed. Example: coannihilations in mSUGRA
Wh2 = 1.43
Wh2 = 0.135
Edsjö, Schelke, Ullio & Gondolo
2003  DarkSUSY generally
accurate to 1 %.
In most cases, DarkSUSY and MicrOMEGAs now agree to
better than a fraction of a percent. (Exception: the highestmass models; cross-checking is currently going on)
Methods of WIMP Dark Matter detection:
• Discovery at accelerators (Fermilab, LHC,..)
• Direct detection of halo particles in terrestrial
• Indirect detection of neutrinos, gamma rays,
radio waves, antiprotons, positrons in earth- or
space-based experiments
d si
 2 Zf p  ( A  Z ) f n FA (q)  A2
dq v
The basic process for indirect detection is
annihilation, e.g, neutralinos:
Neutralinos are Majorana particles
ann  nv
Enhanced for
clumpy halo; near
galactic centre
and in Sun &
Direct ”detection” by DAMA – controversial issue
since 1997…
R. Bernabei et al, astroph/0307403; 107 800 kg days, >
6  effect!
DAMA favoured
DAMA 129Xe
NAIAD 2005
CDMS Soudan data Phys.
Rev. Lett. 93:211301, 2004,
DAMA excluded for spin
independent scattering
DAMA still
CDMS 2004
Whatever it is, it is not MSSM - Kurylov & Kamionkowski, Phys. Rev.
D69:063503, 2004 : SD < 4 · 10-3 pb for MSSM (ns from the Sun)
Gondolo & Gelmini, hep-ph/0504010: Different detection thresholds
for different experiments can give agreement for very low mass
WIMPs, 5 - 9 GeV
DAMA region
Preferred parameter
space if muon g-2
anomaly is explained
Baltz & Gondolo, hep-ph/0407039
NAIAD, UK Dark Matter
Collaboration, G.J. Alner et al., hepex/0504031
J. Gascon, astro-ph/0504241
New proposal: Super-CDMS
(P. L. Brink et al., astroph/0503583)
Model for Neutralino Galactic Halo:
local  0.3 GeV/cm3, v/c  10-3, m  100 GeV
 flux 103 cm-2 s-1 sr-1 !
Diemand, Moore & Stadel, 2005:
The first structures to form are
mini-halos of 10-6 solar masses.
There would be zillions of them
surviving and making up a sizeable
fraction of the dark matter halo.
Maybe the dark matter detection
schemes will have to be quite
(For instance, when the Earth
enters such a solar system-sized
object, counting rates would be very
high, and then drop drastically…)
Much more work, both analytically,
numerically and observationally
will be needed to settle this
interesting issue.
Neutrinos from
the Earth (& Sun
– but Sun more
difficult for
Neutralino signal: Neutrinos from
the Earth & Sun, MSSM
• Present case: 25 GeV threshold, WMAP relic density, CDMS-II
limit on cross section
• Future: 25 GeV threshold, WMAP relic density, SI < 10-8 pb
See PS talk by Lundberg
Indirect detection
through g-rays. Two
types of signal:
Continuous (large rate
but at lower energies,
difficult signature) and
Monoenergetic line
(often too small rate but
is at highest energy Eg =
m; ”smoking gun”)
continuous g
g line, gg
m  50 GeV
m  300 GeV
Advantage of gamma
rays: point back to the
source. Enhanced flux
possible thanks to halo
density profile and
substructure (as
predicted by CDM)
L.B., P.Ullio & J. Buckley 1998
Example: 1.4 TeV higgsino with WMAP-compatible
relic density (L.B., T. Bringmann, M. Eriksson and
M. Gustafsson, hep-ph/0507229)
New contribution (internal
Gamma-ray spectrum seen by an
ideal detector
Intrinsic line width DE/E ~ 10-3
Same spectrum seen with 15% energy
”Miracles” in gamma-rays for heavy (> 1 TeV) neutralinos:
• Heavy MSSM neutralinos are almost pure higgsinos (in
standard scenario) or pure winos (in AMSB & split SUSY
• Just for these cases, the gamma line signal is particularly
large (L.B. & Ullio, 1998)
• In contrast to all other detection scenarios (accelerator,
direct detection, positrons, antiprotons, neutrinos,..) the
expected signal/background increases with mass  unique
possibility, even if LHC finds nothing.
• Rates are further enhanced by non-perturbative binding
effects in initial state (Hisano, Matsumoto & Nojiri, 2003)
• There are many large Air Cherenkov Telescopes (ACT)
either being built or already operational (CANGAROO,
HESS, MAGIC, VERITAS) that cover all the interesting
energy range, Eg  20 TeV
Interesting development for high-mass WIMPs:
Hisano, Matsumoto and Nojiri, PRL 2003; Hisano,
Matsumoto, Nojiri and Saito, hep-ph/0412403
Neutralino and chargino nearly degenerate; attractive Yukawa force from
W and Z exchange  bound states near zero energy  enhancement of
annihilation rate for small (Galactic) velocities. Little effect on relic
density (higher v). ”Explosive annihilation”!
In MSSM without standard GUT
condition (AMSB; split SUSY) mwino 
2 – 3 TeV; m ~ 0.2 GeV
Factor of 100 – 1000 enhancement of
annihilation rate possible. B.R. to gg
and Zg is of order 0.2 – 0.8!
Non-perturbative resummation
explains large lowest-order rates to gg
and Zg. It also restores unitarity at
largest masses
F. Boudjema, A. Semenov, D. Temes, hep-ph/0507127
Wino case
P. Ullio, 2001, AMSB scenario (cf Arvanitaki & Graham hepph/0411376; Masiero, Profumo, Ullio, hep-ph/0412058; Cheung
and Chiang hep-ph/0501265 – split SUSY)
Zg line is
strong for
wino DM
July 2004: H.E.S.S. 2003 data
towards galactic centre (June 2005:
preliminary 2004 data released)
Fit to CANGAROO data
D. Horns, astro-ph/0408192; Parallel Session SUSY2005
m = 1.1 TeV (probably obsolete data)
m = 18 TeV, too high for neutralino? Spectrum
probably looks quite different (L.B., T.Bringmann,
M.Eriksson, M. Gustafsson, 2005)
Dark matter annihilation?
E2F(E) [TeV/cm2s]
HESS Preliminary
20 TeV Neutralinos
20 TeV KK particle
E [TeV]
P. Vincent, Cividale del Friuli Workshop, June, 2005
Spectra will actually be
very similar – the SUSY
spectrum gets
contribution from
gamma-line and radiation
from W pairs for winos or
higgsinos. However, no
one has found a viable
MSSM model yet…
Dark matter annihilation?
E2F(E) [TeV/cm2s]
HESS Preliminary
20 TeV Higgsinos
20 TeV Neutralinos
20 TeV KK particle
E [TeV]
P. Vincent, Cividale del Friuli Workshop, June, 2005
Spectra will actually be
very similar – the SUSY
spectrum gets
contribution from
gamma-line and radiation
from W pairs for winos or
higgsinos. However, no
one has found a viable
MSSM model yet…
L.B., T. Bringmann, M.
Eriksson, M. Gustafsson,
Dark matter annihilation?
E2F(E) [TeV/cm2s]
HESS Preliminary
4 TeV Higgsinos
20 TeV Neutralinos
20 TeV KK particle
E [TeV]
P. Vincent, Cividale del Friuli Workshop, June, 2005
Spectra will actually be
very similar – the SUSY
spectrum gets
contribution from
gamma-line and radiation
from W pairs for winos or
higgsinos. However, no
one has found a viable
MSSM model yet…
L.B., T. Bringmann, M.
Eriksson, M. Gustafsson,
(-Germany) collaboration, launch 2007
GLAST can search for dark matter signals
up to 300 GeV. (It is also likely to detect a
few thousand new GeV blazars …)
W. de Boer, astro-ph/0412620 (see talk at parallel session)
Excess of gamma-rays
Filled by 65 GeV
Galactic rotation curve
Data explained by 65-100 GeV neutralino?
cf. also A. Cesarini et al., 2003: large ”boost
factor” needed. Is that compatible with the
measured antiproton flux?
Also, how reliable is GALPROP for the background?
Wait for GLAST data: does the endpoint signal
spectrum end in a line?
Finkbeiner, astro-ph/0409027: WMAP synchrotron
foreground, ”haze”, can be explained by neutralino DM
EGRET points have been
moved down by
reconsidering galactic
foreground, GLAST will
also resolve more AGNs
Diffuse cosmic
Idea: Redshifted gamma-ray
line gives peculiar energy
feature – may be observable
for CDM-type (Moore profile)
cuspy halos and substructure
Ullio, Bergström & Edsjö, 2002
Could the diffuse extragalactic gamma-ray background be
generated by neutralino annihilations? GeV ”bump”? (Moskalenko, Strong,
Reimer, 2004)
Steep (Moore) profile needed for DM substructure; some finetuning to get high annihilation rate
Elsässer & Mannheim, Phys. Rev. Lett. 94:171302, 2005
GLAST will tell!
Problem (Ando, PRL 2005): It is difficult to reproduce extragalactic result of
Elsässer & Mannheim, without overproducing gammas from g.c.
Resolution (Oda, Totani & Nagashima, astroph/0504096): clumpy halos; tidal effects remove
substructure near centres of haloes
Effects of a clumpy halo on diffuse
galactic plus extragalactic gamma-ray
signal. Satisfies bound from gal. centre:
Oda, Totani and Nagashima, astro-ph/0504096; cf.
also Pieri, Branchini and Hofmann, astro-ph/0505356
INTEGRAL all-sky picture of positronium gamma line (511 keV) emission
– unknown origin (J. Knödlseder et al., astro-ph/0506026)
Is it dark matter annihilation (very low mass needed: 10 - 20 MeV)?
Could also be explained by type Ia supernovae, or low mass X-ray
Boehm, Hooper, Silk, Casse, Paul (2003):
Galactic positrons (511 keV line) from low mass (10 – 100 MeV) dark matter particle
decay or annihilation? Beacom, Bell, Bertone (2004): mass has to be less than 20 MeV
due to radiative processes
  r g
2005 data:
Y. Ascasibar & al., astro-ph/0507142: g = 1.03 ± 0.04,
INTEGRAL satellite measurements
Problem: How does one find a reasonable particle
physics candidate with low mass and strong
couplings to electrons?? (Boehm & Fayet, 2003
have some models, also Kawasaki & Yanagida, hepph/0505157)
P. Serpico and G. Raffelt, astro-ph/0403417
Light (5 – 15 MeV) dark matter actually improves agreement
with BBN!
D. Hooper et al (astro-ph/031115): If signal is due to light
dark matter annihilation, a flux should also be detectable, 
~ (1-7)·10-4 cm-2s-1 , from Sagittarius dwarf spheroidal galaxy.
New INTEGRAL upper limit (June, 2005):
 < 1.7 ·10-4 cm-2s-1  almost entire range excluded.
However, depends on density shape of subhalo vs halo.
Ahn and Komatsu, astro-ph/0506520: What
gives the diffuse extragalactic gamma-ray
background above 3 - 4 MeV?
(Höflich, 2005)
20 MeV Dark Matter
• The existence of Nonbaryonic Dark Datter has been definitely
• CDM is favoured
• Supersymmetric particles (in particular, neutralinos) are still
among the best-motivated candidates
• New direct and indirect detection experiments will reach deep
into theory parameter space, some even deeper than LHC
• Indications of gamma-ray excess from Galactic center (at MeV,
GeV, and TeV energies!) However, need more definitive
spectral signature – the gamma line would be a ”smoking gun”
• The various indirect and direct detection methods are
complementary to each other and to LHC
• The hunt is going on – many new experiments coming!
• The dark matter problem may be near its (s)solution…
Presentation  - Flemish Supercomputer Centre
Presentation - Flemish Supercomputer Centre