Dan Hooper

1
What Can We Learn About Supersymmetry From
Astrophysical Experiments?

• Dan Hooper
• Particle Astrophysics Center
• Fermi National Laboratory
• dhooper_at_fnal.gov

University of Oregon Cosmo/Astro
Mini-Workshop May 22-26, 2006
2
Based On M. Carena, DH, P. Skands,
hep-ph/0603180 F. Halzen, DH, hep-ph/0510048, PRD
DH and Andrew Taylor (in preparation)
3
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 1970s)
• White dwarfs, brown dwarfs, Jupiter-like planets,
  neutron stars, black holes, etc?

4
The Dark Matter Density

• WMAP best-fit LCDM model (for a flat Universe)
• 73 Dark energy (WL? 0.73)
• 27 Matter (?Mh2 0.27)
• ??h2 ? 0.0076

5

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
6

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 Universes matter must be Cold Dark
  Matter

7
The world is full of obvious things which nobody
by any chance ever observes. -Sherlock Holmes

8
The Particle Nature of Dark Matter
Axions, Neutralinos, Gravitinos, Axinos,
Kaluza-Klein States, Heavy Fourth Generation
Neutrinos, Mirror Particles, Stable States in
Little Higgs Theories, WIMPzillas, Cryptons,
Sterile Neutrinos, Sneutrinos, Light Scalars,
Q-Balls, D-Matter, SuperWIMPS, Brane World Dark
Matter,
A virtual zoo of dark matter candidates have been
proposed over the years. 100s of viable
candidates. Weakly Interacting Massive Particles
(WIMPs) are a particularly attractive class of
dark matter candidates.
9
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

10
The Lightest Neutralino
Higgsinos
Bino
Wino

• 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 LSPs 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

11
Can Astrophysics Measure ??
12
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

13
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

14
Supersymmetry At The LHC

• Squarks/gluinos decay to leptonsjetsmissing
  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?

15
Astrophysical Dark Matter Experiments

• Direct Detection
• - Momentum transfer to detector
• through elastic scattering
• Indirect Detection
• - Observation of annihilation
• products (?, e, p, ?, etc.)

16
Direct Detection

• Underground experiments hope to detect recoils of
  dark matter particles elastically scattering off
  of their detectors
• Prospects depend on the neutralinos elastic
  scattering cross section with nuclei
• Leading experiments include CDMS (Minnesota),
  Edelweiss (France), and Zeplin (UK)

17
Direct Detection

• Elastic scattering can occur through Higgs and
  squark exchange diagrams

?
?
?
?

q
h,H
q
q
q
q
SUSY Models

• Cross section depends on numerous SUSY
  parameters neutralino mass and composition,
  tan?, squark masses and mixings, Higgs masses and
  mixings

18
Direct Detection

• Current Status

Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric Models

19
Direct Detection

• Near-Future Prospects

Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric Models
CDMS, Edelweiss Projections

20
Direct Detection

• Long-Term Prospects

Zeplin, Edelweiss
DAMA
CDMS
Supersymmetric Models
Super-CDMS, Zeplin-Max

21
Direct Detection

• But what does direct detection tell us?
• Models with large cross sections
  are dominated by Higgs exchange,
  couplings to 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

22
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

23
Searches For Heavy MSSM Higgs at the Tevatron

• Projected Reach
• 
  

Both depend on tan?, mA
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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
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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
26
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
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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

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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

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Indirect Detection Neutrinos

• Neutrino flux depends on the capture rate, which
  is in turn tied to the neutralinos elastic
  scattering cross section
• Direct detection limits impact rates anticipated
  in neutrino telescopes

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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-Dependent
Spin-Independent
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Indirect Detection Neutrinos
What Kind of Neutralino Has a Large
Spin-Dependent Coupling?
?
Z
q
q
q
q
q
q
Always Small
? fH12 - fH22
Substantial Higgsino Component Needed
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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)
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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)
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Indirect Detection Neutrinos

• Rates complicated by competing scalar and axial
  vector scattering
• Future bounds by CDMS will simplify neutrino rate
  considerably

100 Times Stronger Constraint
Current CDMS Constraint


High Neutrino Rates
Hooper and A. Taylor
F. Halzen and Hooper (hep-ph/0510048)
35
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

36
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?

37
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
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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
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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
• ?h20.1 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)

40
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

41
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), poor DM
  candidate
• 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)
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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
43
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)

44
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
  still not identifiable with planned
  experiments (GLAST, etc.)
• Neutralino mass and annihilation cross
  section may be roughly extracted

45
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

46
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
47
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 neutralinos annihilation cross section

48
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

49
Indirect Detection Positrons

• Determine positron spectrum at Earth by solving
  diffusion equation

Energy Loss Rate
Diffusion Constant
Source Term

• Inputs
• Diffusion constant
• Energy loss rate
• Annihilation cross section/modes
• Halo profile (inhomogeneities?)
• Boundary conditions
• Neutralino mass

50
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

51
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 (???)

52
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)
53
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)
54
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
• Non-thermal scenarios (AMSB, etc), can be easily
  tested

Value for thermal abundance
Hooper and J. Silk, PRD (hep-ph/0409104)
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Putting It All Together
Direct Detection
Neutrino Telescopes

?-Rays e
56
Putting It All Together

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SUSY Benchmark Models

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SUSY Benchmark Models

59
SUSY Benchmark Models

Squark decay kinematics
A/H ? ? ?-
60
SUSY Benchmark Models

Atmospheric ? BG
BF
Uncertainty In Local Density
61
Combining LHC With Astrophysics
Benchmark model LT1 M2120 GeV, ?302 GeV,
mA352 GeV, tan?56, 1700 GeV squarks LHC m?
59 10, msquark1700 10, tan?56 15,
mA352 1 Astro ??N7 10-8 x/? 2, R? yr-1, ????Z / ?tot

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Combining LHC With Astrophysics
Benchmark model LT1 M2120 GeV, ?302 GeV,
mA352 GeV, tan?56, 1700 GeV squarks LHC m?
59 10, msquark1700 10, tan?56 15,
mA352 1 Astro ??N7.10-8 x/? 2, R? yr-1, ????Z / ?tot

What can be inferred about the lightest
neutralinos composition?
63
Combining LHC With Astrophysics
Benchmark model LT1 M2120 GeV, ?302 GeV,
mA352 GeV, tan?56, 1700 GeV squarks LHC
m? 59 10, msquark1700 10, tan?56
15, mA352 1 Astro ??N7.10-8 x/? 2,
R?

LHCRelic Density
Actual Value
Astro(CDMS)
64
Combining LHC With Astrophysics
Benchmark model LT1 M2120 GeV, ?302 GeV,
mA352 GeV, tan?56, 1700 GeV squarks LHC
m? 59 10, msquark1700 10, tan?56
15, mA352 1 Astro ??N7.10-8 x/? 2,
R?

LHCRelic Density
Astro(CDMS)
65
Combining LHC With Astrophysics
Benchmark model LT2 M2168 GeV, ?351 GeV,
mA326 GeV, tan?56, 430 GeV squarks

Astrophysics adds little information in this case
(beyond confirmation)
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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

69
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.
70
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
• 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)

71
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
• 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)
72
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

73
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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DZERO
CMS
ANTA
ZEPLIN
A T L S

RES
H E S
I C E C U B E
CDF
D M S
VERITAS
M A G I C
GLAST
I C E
A
M E L A
P
M S
Lets use all of the tools we have to solve the
puzzle of supersymmetry!