Transcript Document 7403840

Dan Hooper
Particle Astrophysics Center
Fermi National Laboratory
[email protected]
University of Oregon
Cosmo/Astro Mini-Workshop
May 22-26, 2006
Based On:
M. Carena, DH, P. Skands, hep-ph/0603180
F. Halzen, DH, hep-ph/0510048, PRD
DH and Andrew Taylor (in preparation)
The Existence of
Dark Matter
•Galaxy and cluster rotation
curves have pointed to the
presence of large quantities
of non-luminous matter for
many decades (compelling
since the 1970’s)
•White dwarfs, brown
dwarfs, Jupiter-like planets,
neutron stars, black holes,
etc?
The Dark Matter Density
WMAP best-fit LCDM model
(for a flat Universe):
•73 % Dark energy (WL = 0.73)
•27 % Matter (WMh2 = 0.27)
•Wh2  0.0076
Baryonic Abundance
•Big Bang nucleosynthesis
combined with cosmic
microwave background
determine WBh2  0.024
•But, we also know WM ~ 0.3, so
most of the matter in the
Universe is non-baryonic dark
matter!
Fields and Sarkar, 2004
Cold Dark Matter and
Structure Formation
•Observations of the large scale
structure of our Universe can be
compared to computer
simulations
•Simulation results depend
primarily on whether the dark
matter is hot (relativistic) or
cold (non-relativistic) when
structures were formed
•Most of the Universe’s matter
must be Cold Dark Matter
“The world is full of obvious things which
nobody by any chance ever observes.”
-Sherlock Holmes
The Particle Nature of Dark Matter
Axions, Neutralinos,
Gravitinos, Axinos, KaluzaKlein States, Heavy Fourth
Generation Neutrinos,
Mirror Particles, Stable
States in Little Higgs
Theories, WIMPzillas,
Cryptons, Sterile Neutrinos,
Sneutrinos, Light Scalars, QBalls, D-Matter,
SuperWIMPS, Brane World
Dark Matter,…
A virtual zoo of dark matter
candidates have been
proposed over the years.
100’s of viable candidates.
Weakly Interacting Massive
Particles (WIMPs) are a
particularly attractive class
of dark matter candidates.
Supersymmetry






Introduces new bosons for fermions and
vice versa
Elegant extension of the Standard Model
Natural solution to hierarchy problem
(stabilizes quadradic divergences to
Higgs mass)
Restores unification of couplings
Requirement of proton stability implies the
stability of the Lightest Supersymmetric
Particle (LSP) by the virtue of R-parity
The lightest neutralino is among the most
natural possibilities for the LSP
The Lightest Neutralino
Bino
Wino
Higgsinos
•Properties of the lightest neutralino can vary wildly depending on its
composition
•The composition of the lightest neutralino will likely not be determined
at the LHC
•Annihilation and elastic scattering cross sections with nucleons can vary
over many orders of magnitude depending on LSP’s composition (and
sparticle spectrum, tan , etc.)
By including astrophysical measurements with LHC data, it may be
possible to determine the composition of the lightest neutralino
Can Astrophysics Measure ?
Supersymmetry At
The Tevatron
•Most promising channel is through neutralino-chargino production
For example,
•For the case of light mA and large tan, heavy MSSM higgs bosons
(A/H) are observable
•Tevatron searches for light squarks and
gluinos are also interesting
•Tevatron SUSY searches only possible if
superpartners are rather light
Supersymmetry At
The LHC
•Squarks and gluinos will be
produced prolifically at the
LHC
•Squarks/gluinos decay to
distinctive combinations of
leptons, jets and missing
energy (LSPs)
•Capable of discoverying
squarks/gluinos as heavy as
~3 TeV
Supersymmetry At
The LHC
•Squarks/gluinos decay to leptons+jets+missing energy (LSPs)
•By studying decay kinematics, lightest neutralino mass to be
measured to ~10% precision
•Masses of sleptons and heavier neutralinos may also be
determined if sufficiently light
•But what is the nature of the LSP?
•Is it dark matter?
Astrophysical Dark Matter
Experiments
•Direct Detection
- Momentum transfer to detector
through elastic scattering
•Indirect Detection
- Observation of annihilation
products (, e+, p, , etc.)
Direct Detection
•Underground experiments hope to detect recoils of dark
matter particles elastically scattering off of their detectors
•Prospects depend on the neutralino’s elastic scattering cross
section with nuclei
•Leading experiments include CDMS (Minnesota), Edelweiss
(France), and Zeplin (UK)
Direct Detection
•Elastic scattering can occur through Higgs and squark exchange
diagrams:




q~
h,H
q
q
q
q
•Cross section depends on numerous SUSY
parameters: neutralino mass and composition,
tan, squark masses and mixings, Higgs
masses and mixings
SUSY Models
Direct Detection
•Current Status
Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric
Models
Direct Detection
•Near-Future Prospects
Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric
Models
CDMS, Edelweiss
Projections
Direct Detection
•Long-Term Prospects
Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric
Models
Super-CDMS, Zeplin-Max
Direct Detection
But what does direct detection tell us?
•Models with large cross sections
dominated by Higgs exchange,
b, s quarks
•Squark exchange contribution
substantial only below ~10-8 pb
•Leads to correlation between
neutralino composition, tan , mA
and the elastic scattering rate
are
couplings to
Searches For Heavy MSSM Higgs
at the Tevatron
•Heavy (A/H) MSSM higgs searches at the Tevatron/LHC are
most sensitive for models with small mA and large tan
p p  A/H X + - X
p p  A/H bb bb bb
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Searches For Heavy MSSM Higgs
at the Tevatron
Projected Reach
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Both depend on tan, mA
Direct Detection and
Collider Searches
Current
CDMS Limit
For a wide range of M2 and , much stronger current limits on
tan, mA from CDMS than from the Tevatron
M. Carena, Hooper, P. Skands, hep-ph/0603180
Direct Detection and
Collider Searches
3 discovery reach, 4 fb-1
Projected 2007 CDMS Limit
(assuming no detection)
Limits from CDMS imply
heavy Higgs (H/A) is beyond
the reach of the Tevatron,
unless LSP has a very small
higgsino fraction (>>M2)
M. Carena, Hooper, P. Skands, hep-ph/0603180
Direct Detection and
Collider Searches
Constrained heavy Higgs (A/H) discovery potential at the Tevatron (4 pb-1)
H/A discovery (3) not
possible given current
CDMS limits
H/A discovery (3) not
possible given projected
2007 CDMS limits
(assuming no detection)
M. Carena, Hooper, P. Skands, hep-ph/0603180
Indirect Detection:
Neutrinos
•WIMPs elastically scatter with massive bodies (Sun)
•Captured at a rate ~ 1018 s-1 (p/10-8 pb) (100 GeV/m)2
•Over billions of years, annihilation/capture rates equilibrate
•Annihilation products are absorbed, except for neutrinos
Indirect Detection:
Neutrinos
The IceCube Neutrino Telescope
•Full cubic kilometer instrumented volume
•Technology proven with predecessor, AMANDA
•First string of detectors deployed in 2004/2005,
8 more strings deployed in 2005/2006 (80 in total)
•Sensitive to muon neutrinos above ~ 100 GeV
•Similar physics reach to KM3 in
Mediterranean Sea
Indirect Detection:
Neutrinos
•Neutrino flux depends on the capture rate, which is in turn tied to the
neutralino’s elastic scattering cross section
•Direct detection limits impact rates anticipated in neutrino telescopes
Indirect Detection: Neutrinos
•Neutralinos become captured in the Sun through spin-independent and
spin-dependent scattering
•Direct detection constraints on spin-dependent scattering are still very weak
Spin-Independent
Spin-Dependent
Indirect Detection:
Neutrinos
What Kind of Neutralino Has a Large Spin-Dependent Coupling?

Z
q
q
q
qq
 |fH1|2 - |fH2|2
Always Small
Substantial Higgsino Component Needed
Indirect Detection:
Neutrinos
What Kind of Neutralino Has a Large Spin-Dependent Coupling?
High Neutrino
Rates
Hooper and A. Taylor;
F.
Halzen and Hooper (hep-ph/0510048)
Indirect Detection:
Neutrinos
•Rates complicated by competing scalar and axial vector scattering
Current CDMS Constraint
Hooper and A. Taylor;
F.
Halzen and Hooper (hep-ph/0510048)
Indirect Detection:
Neutrinos
•Rates complicated by competing scalar and axial vector scattering
•Future bounds by CDMS will simplify neutrino rate considerably
Current CDMS Constraint
100 Times Stronger Constraint
High Neutrino
Rates
Hooper and A. Taylor;
F.
Halzen and Hooper (hep-ph/0510048)
Indirect Detection:
Gamma-Rays
Advantages of Gamma-Rays
•Propagate undeflected (point sources possible)
•Propagate without energy loss (spectral information)
•Distinctive spectral features (lines), provide potential “smoking gun”
•Wide range of experimental technology (ACTs, satellite-based)
Disadvantages of Gamma-Rays
•Flux depends critically on poorly known inner halo profiles
 predictions dramatically vary from model to model
•Unknown astrophysical backgrounds
Indirect Detection: Gamma-Rays
The Galactic Center Region
•Likely to be the brightest source of dark matter annihilation radiation
•Detected in ~TeV gamma-rays by four ACTs:
Cangaroo-II, Whipple, HESS and MAGIC
•Possible evidence for dark matter?
Indirect Detection: Gamma-Rays
The Cangaroo-II Observation
•Consistent with WIMP in ~1-4 TeV mass range
•Roughly consistent with Whipple/Veritas
Hooper, Perez, Silk, Ferrer and Sarkar, JCAP, astro-ph/0404205
Indirect Detection: Gamma-Rays
The Cangaroo-II Observation
•Consistent with WIMP in ~1-4 TeV mass range
•Roughly consistent with Whipple/Veritas
The HESS Obsevation
•Superior telescope
•Inconsistent with Cangaroo-II
•Extends at least to ~10 TeV
•WIMP of ~10-40 TeV mass
needed
D. Horns, PLB, astro-ph/0408192
Indirect Detection: Gamma-Rays
Can A Neutralino Be As Heavy As 10-40 TeV?
•Very heavy neutralinos tend to overclose the Universe
•Largest annihilation cross sections (lowest relic abundance) are found for
Wino-like or Higgsino-like neutralinos
•Wh2~0.1 for ~1 TeV Higgsino, or ~3 TeV Wino
•Significantly larger masses are possible only if coannihilations are
carefully arranged (for example, S. Profumo, hep-ph/0508628)
Indirect Detection: Gamma-Rays
Can A Neutralino Be As Heavy As 10-40 TeV?
•Electroweak precision observables indicate the presence of a light higgs
boson (near the EW scale)
•Large contributions to the higgs mass come from particle loops:
•In unbroken SUSY, boson and fermion loops exactly cancel
• If mSUSY >> mHiggs , extreme fine tuning required
•mSUSY below ~1 TeV is strongly preferred
Indirect Detection: Gamma-Rays
Messenger Sector Dark Matter
•In Gauge Mediated SUSY Breaking (GMSB) models, SUSY is broken
in ~100 TeV sector
•LSP is a light gravitino (1-10 eV),
DM candidate
poor
•Lightest messenger particle is naturally
stable, multi-TeV scalar neutrino is a
viable dark matter candidate
•Generated gamma-ray spectrum not
inconsistent with HESS/MAGIC source
Dimopolous, Giudice, Pomarol; Han, Hemfling; Han, Marfatia, Zhang;
Hooper and March-Russell, PLB (hep-ph/0412048)
Indirect Detection: Gamma-Rays
Astrophysical Origin of Galactic Center Source?
•A region rich in extreme astrophysical objects
•Particle acceleration associated with supermassive black hole?
Aharonian and Neronov (astro-ph/0408303),
Atoyan and Dermer (astro-ph/0410243)
•Nearby Supernova Remnant to close
to rule out
•If this source is of an astrophysical
nature, it would represent a extremely
challenging background for future
dark matter searches to overcome
(GLAST, AMS, etc.)
Hooper, Perez, Silk, Ferrer and Sarkar, JCAP, astro-ph/0404205
Indirect Detection: Gamma-Rays
Dwarf Spheriodal Galaxies
•Several very high mass-to-light dwarf galaxies in Milky Way
(Draco, Sagittarius, etc.)
•Little is known for certain about the halo profiles of such objects
•For example, draco mass estimates range from 107 to 1010 solar masses
 broad range of predictions for annihilation rate/gamma-ray flux
•May provide several very bright sources of dark matter annihilation radiation…
or very, very little
•Detection of Draco by CACTUS experiment???
(Bergstrom, Hooper, hep-ph/0512317; Profumo, Kamionkowski, astro-ph/0601249)
Indirect Detection: Gamma-Rays
What Does the Gamma-Ray Spectrum Tell Us?
•Most annihilation modes generate very similar spectra
•+- mode is the most distinctive, although
not identifiable with planned
experiments (GLAST, etc.)
•Neutralino mass and annihilation cross
section may be roughly extracted
still
Indirect Detection: Gamma-Rays
What Does the Gamma-Ray Spectrum Tell Us?
•At loop level, neutralinos annihilate to  and Z final states
•Distinctive spectral line features
•If bright enough, fraction of neutralino annihilations to lines can be measured
Indirect Detection: Gamma-Rays
What Does the Gamma-Ray Spectrum Tell Us?
•Chargino-W+/- loop diagrams
provide largest contributions
in most models
•Cross sections largest for
higgsino-like (or wino-like)
neutralinos
•Knowledge of squark masses
makes this correlation more
powerful
A. Taylor, Hooper, in preparation
Indirect Detection: Positrons
•Gamma-ray observations can tell us the fraction of neutralino
annihilation to various modes (, Z), but cannot measure the total
cross section
•Positron spectrum generated in neutralino annihilations is
dominated by local dark matter distribution (within a few kpc)
•Considerably less uncertainty in the local density than the density of
inner halo profiles
•Cosmic positron measurements can roughly measure the
neutralino’s annihilation cross section
Indirect Detection: Positrons
•Positrons produced through a range of neutralino annihilation channels:
(decays of heavy quarks, heavy leptons, gauge bosons, etc.)
•Positrons move under influence of galactic magnetic fields
•Energy losses through inverse compton and synchotron scattering with
starlight, CMB
Indirect Detection: Positrons
•Determine positron spectrum at Earth by solving diffusion equation:
Inputs:
Diffusion Constant
•Diffusion constant
•Energy loss rate
•Annihilation cross
section/modes
•Halo profile
(inhomogeneities?)
•Boundary conditions
•Neutralino mass
Energy Loss Rate
Source Term
Indirect Detection: Positrons
The HEAT Excess(?)
•The HEAT balloon flights have measured an excess in the cosmic positron
fraction between 5-30 GeV, although considerable ambiguities exist
•Neutralinos can generate
the observed spectral shape,
but requires an annihilation
rate a factor of ~50 or more
above the rate expected for
a thermal relic and a
homogeneous dark matter
distribution
Indirect Detection: Positrons
Where does this leave us?
•Future cosmic positron experiments hold great promise
•PAMELA satellite, planned to be launched in 2006
•AMS-02, planned for deployment
onboard the ISS (???)
Indirect Detection: Positrons
With a “HEAT sized” signal:
•Dramatic signal for either PAMELA or AMS-02
•Clear, easily identifiable signature of dark matter
Hooper and J. Silk, PRD (hep-ph/0409104)
Indirect Detection: Positrons
With a smaller signal:
•More difficult for PAMELA or AMS-02
•Still one of the most promising dark matter search techniques
Hooper and J. Silk, PRD (hep-ph/0409104)
Indirect Detection: Positrons
Prospects for Neutralino Dark Matter:
•AMS-02 can detect a thermal
(s-wave) relic up to ~200 GeV, for
any boost factor, and all likely
annihilation modes
•For modest boost factor of ~ 5,
AMS-02 can detect dark matter
as heavy as ~1 TeV
•PAMELA, with modest boost
factors, can reach masses of ~250
GeV
Value for thermal abundance
•Non-thermal scenarios (AMSB,
etc), can be easily tested
Hooper and J. Silk, PRD (hep-ph/0409104)
Putting It All Together
Direct Detection
Neutrino Telescopes
-Rays + e+
Putting It All Together
SUSY Benchmark Models
SUSY Benchmark Models
SUSY Benchmark Models
Squark decay kinematics
A/H  + -
SUSY Benchmark Models
Uncertainty In Local Density
Atmospheric  BG
BF < 10
Combining LHC With Astrophysics
Benchmark model LT1:
M2=120 GeV, =302 GeV, mA=352 GeV, tan=56, 1700 GeV squarks
LHC: m= 59 ± 10%, msquark=1700 ± 10%, tan=56 ± 15%, mA=352 ± 1%
Astro: N=7 10-8 x/ 2, R < 10 yr-1, +Z / tot < 10-5
Combining LHC With Astrophysics
Benchmark model LT1:
M2=120 GeV, =302 GeV, mA=352 GeV, tan=56, 1700 GeV squarks
LHC: m= 59 ± 10%, msquark=1700 ± 10%, tan=56 ± 15%, mA=352 ± 1%
Astro: N=7.10-8 x/ 2, R < 10 yr-1, +Z / tot < 10-5
What can be inferred about the lightest
neutralino’s composition?
Combining LHC With Astrophysics
Benchmark model LT1:
M2=120 GeV, =302 GeV, mA=352
GeV, tan=56,
1700
GeV squarks
LHC: m= 59 ± 10%,
msquark=1700 ± 10%,
tan=56 ± 15%,
mA=352 ± 1%
Astro: N=7.10-8 x/ 2,
R < 10 yr-1,
+Z / tot < 10-5
LHC+Relic Density
Actual Value
+Astro(CDMS)
Combining LHC With Astrophysics
Benchmark model LT1:
M2=120 GeV, =302 GeV, mA=352
GeV, tan=56,
1700
GeV squarks
LHC: m= 59 ± 10%,
msquark=1700 ± 10%,
tan=56 ± 15%,
mA=352 ± 1%
Astro: N=7.10-8 x/ 2,
R < 10 yr-1,
+Z / tot < 10-5
LHC+Relic Density
+Astro(CDMS)
Combining LHC With Astrophysics
Benchmark model LT2:
M2=168 GeV, =351 GeV, mA=326
GeV, tan=56,
430 GeV
squarks
Astrophysics adds little
information in this case
(beyond confirmation)
Combining LHC With Astrophysics
•In most/many SUSY models, the higgsino fraction () can be
constrained considerably more tightly if astrophysics data is included
•Can break coannihilation/funnel/bulk degeneracies
•Sign of  is not determined
•In heavier SUSY models, LHC will measure few particles, making
astrophysical measurements more valuable
Combining LHC With Astrophysics
•In most/many SUSY models, the higgsino fraction () can be
constrained considerably more tightly if astrophysics data is included
•Can break coannihilation/funnel/bulk degeneracies
•Sign of  is not determined
•In heavier SUSY models, LHC will measure few particles, making
astrophysical measurements more valuable
In Progress: constraints on tan, mA, stop/sbottom masses, etc.
A Few Caveats
•MSSM, extended SUSY models may have very different phenomenology
 Perhaps astro can be used to confirm that we are in the MSSM?
•M1 = M2 / 2 (what is relevant is M1 << M2)
•Common sfermion mass scale (role of sleptons may be important)
•Astrophysical uncertainties (local dark matter density, velocity dist, etc.)
•No large CP-violating phases in  (can reduce direct rates)
•Nature is supersymmetric (not easily distinguished from UED, little Higgs,
etc. by LHC)
A Few Caveats
•MSSM, extended SUSY models may have very different phenomenology
 Perhaps astro can be used to confirm that we are in the MSSM?
•M1 = M2 / 2 (what is relevant is M1 << M2)
•Common sfermion mass scale (role of sleptons may be important)
•Astrophysical uncertainties (local dark matter density, velocity dist, etc.)
•No large CP-violating phases in  (can reduce direct rates)
•Nature is supersymmetric (not easily distinguished from UED, little Higgs,
etc. by LHC) DH, G. Kribs (soon to be in preparation)
Summary
•Very exciting prospects exist for direct, indirect and collider searches for
supersymmetry
•The LHC (or perhaps the Tevatron) are exceedingly likely to discover
supersymmetry (or whatever other new physics is associated with the
electroweak scale), but is likely to tell us little about it (squark masses, LSP
mass, perhaps some sleptons and heavy neutralinos, but not much else)
•Astrophysical probes of neutralino dark matter can fill in some of the gaps
in our post-LHC understanding of supersymmetry
Summary
•Direct detection experiments (CDMS) have reached ~10-7 pb level, with 1-2
orders of magnitude expected in near future (many of the most attractive
SUSY models)
•Kilometer scale neutrino telescopes (IceCube, KM3) will be capable of
detecting mixed gaugino-higgsino neutralinos, or constrain the higgsino
fraction
•Cosmic anti-matter searches will be sensitive to (s-wave annihilating)
neutralinos up to hundreds of GeV (PAMELA) or ~1 TeV (AMS-02)
•Gamma-ray astronomy is improving rapidly, possibly enabling
observations of gamma-ray lines; Dwarf spheriodals are among the most
promising sources
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Let’s use all of the tools we have to solve the
puzzle of supersymmetry!