Transcript Neutralino Dark Matter Sabine Kraml, CERN

LHC / ILC / Cosmology
Interplay
Sabine Kraml (CERN)
WHEPP-9, Bhubaneswar, India
3-14 Jan 2006
Outline
Introduction
 Relic density of WIMPs
 SUSY case as illustrative example


Neutralino dark matter
 Requirements for collider tests
 Implications of CP violation

Conclusions
S. Kraml
WHEPP-9 Bhubaneswar
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What is the Universe made of?

Cosmological data:
 4% ±0.4%
baryonic matter
 23% ±4% dark matter
 73% ±4% dark energy

Particle physics:
 SM
is incomplete; expect
new physics at TeV scale
 NP should provide the DM
 Discovery at LHC, precision
measurements at ILC ?
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WHEPP-9 Bhubaneswar
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Dark matter candidates
Neutralino, gravitino, axion,
axino, lightest KK particle,
T-odd little Higgs, branons,
Q-balls, etc., etc...
New Physics
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WIMPs
(weakly interacting massive particles)

DM must be stable, electrically neutral,
weakly and gravitationally interacting

WIMPs are predicted by most BSM theories

Stable as result of discrete symmetries

Produced as thermal relic of the Big Bang

Testable at colliders!
S. Kraml
WHEPP-9 Bhubaneswar
Neutralino, gravitino,
axion, axino, LKP,
T-odd Little Higgs,
branons, Q-balls,
etc., ...
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Relic density of WIMPs
(1)
Early Universe dense and hot;
WIMPs in thermal equilibrium
(2)
Universe expands and cools;
WIMP density is reduced through
pair annihilation; Boltzmann
suppression: n~e-m/T
(3)
Temperature and density too low
for WIMP annihilation to keep up
with expansion rate → freeze out
Final dark matter density: Wh2 2~ 1/<sv>
WMAP: 0.094 < Wh < 0.129 @ 2s
Thermally avaraged cross section of all annihilation channels
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WHEPP-9 Bhubaneswar
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Collider tests of WIMPs

Generic WIMP signature at
LHC: jets (+leptons) + ETmiss
LHC
WMAP

Great for discovery;
resolving the nature of the
WIMP however not obvious

Need precision measurements
of masses, couplings, quantum
numbers, .... → ILC
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WHEPP-9 Bhubaneswar
ILC
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Neutralino-LSP
in the MSSM
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WHEPP-9 Bhubaneswar
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Minimal supersymmetric model


SUSY = Symmetry between fermions and bosons
SM particles
quarks
spin
Superpartners
1/2 squarks
leptons
gauge bosons
Higgs bosons
1/2 sleptons
1
0
gauginos
higgsinos
spin
0
0
1/2
1/2
mix to
2 charginos +
4 neutralinos
If R-parity is conserved the lightest SUSY particle (LSP)
is stable → LSP as cold dark matter candidate
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WHEPP-9 Bhubaneswar
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Neutralino system
Gauginos
Higgsinos
Neutralino mass eigenstates
→ LSP
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WHEPP-9 Bhubaneswar
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Neutralino relic density
Specific mechanisms to get relic density in agreement with WMAP
0.094 < Wh2 < 0.129 puts strong bounds on the parameter space
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WHEPP-9 Bhubaneswar
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mSUGRA parameter space

GUT-scale boundary
conditions: m0, m1/2, A0
[plus tanb, sgn(m)]

4 regions with right Wh2




S. Kraml
bulk (excl. by mh from LEP)
co-annihilation
Higgs funnel (tanb ~ 50)
focus point (higgsino scenario)
WHEPP-9 Bhubaneswar
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Prediction of <sv> from colliders:
What do we need to measure?

LSP mass and decomposition
bino, wino, higgsino admixture

Sfermion masses (bulk, coannhilation)
or at least lower limits on them

Higgs masses and widths: h,H,A

tanb
With which precision?
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WHEPP-9 Bhubaneswar
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What do we need to measure with which precision:
Coannihilation with staus, DM<10
~ GeV




DM(stau-LSP) to 1 GeV
Precise sparticle mixings
Difficult at LHC; soft tau´s!
Achievable at ILC:

Stau mass at threshold
Bambade et al, hep-ph/040601

Stau and Slepton masses
Martyn, hep-ph/0408226

Stau-neutralino mass difference
Khotilovitch et al, hep-ph/0503165
Beam polarization essential!
[Allanach et al, hep-ph/0410091]
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WHEPP-9 Bhubaneswar
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Golden decay chain at LHC

Stau coannihilation region:
leptons will mostly be taus

Small stau-LSP mass
difference DM ≤ 10 GeV
leads to soft t´s

Difficult to measure mtt
kinematic endpoint for
mass determination
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WHEPP-9 Bhubaneswar
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Determination of slepton and LSP masses
at the ILC
[Martyn, hep-ph/0408226]
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WHEPP-9 Bhubaneswar
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Determination of the neutralino system
LHC+ILC case study for SPS1a:
light -inos at ILC; neutralino4 at LHC
[Desch et al., hep-ph/0312069]
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WHEPP-9 Bhubaneswar
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What do we need to measure with which precision:
Higgsino LSP, m ~ M1,2
Fractional accuracies needed

Annihilation into WW and ZZ
via t-channel c± or c0

Rate determined by higgsino
fraction fH=N132+N142

1% precision on M1 and m

All neutralinos/charginos;
mixing via pol. e+e- Xsections

LHC: discovery via 3-body
gluino decays / Drell-Yang
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WHEPP-9 Bhubaneswar
[Allanach et al, hep-ph/0410091]
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Scan of focus point scenario, LCC2
m0 = 3280 GeV, m1/2 = 300 GeV, A0 = 0, tanb = 10
[J.L. Feng et al., ALCPG]
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WHEPP-9 Bhubaneswar
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What do we need to measure with which precision:
Annihilation through Higgs





Mainly cc → A → bb
CP even H exchange is
P-wave suppressed
Fractional accuracies needed
mc and mA to 2%-2‰
(mA-2mc) and m to 5%
A width to 10%
g(Acc)~N132-N142, g(Abb)~hb, ....
[Allanach et al, hep-ph/0410091]
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WHEPP-9 Bhubaneswar
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Influence of mA on evaluation of Wh2
→ large uncertainty if lower limit on mA is not >> 2 mLSP
[Birkedal et al, hep-ph/0507214]
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WHEPP-9 Bhubaneswar
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_
+
e e →




HA
_
A not produced in Higgs-Strahlung, need
→ HA
H,A masses to ~1 GeV; limitation by kinematics!
Widths only to 20%-30%
Production in gg mode can help a lot
e+e
[Heinemeyer et al., hep-ph/0511332]
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WHEPP-9 Bhubaneswar
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Heavy Higgses at LHC
H/A in cascade decays
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WHEPP-9 Bhubaneswar
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For a precise prediction of Wh2
compatible with WMAP acurracy
we need precision measurements
of most of the SUSY spectrum
→ LHC/ILC synergy
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WHEPP-9 Bhubaneswar
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So far considered CP conserving MSSM
What if CP is violated?
[we actually need new sources of CP violation
beyond the SM for baryogenesis]
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WHEPP-9 Bhubaneswar
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CP violation

In the general MSSM, gaugino and higgsino mass
parameters and trilinear couplings can be complex:

Important influence on sparticle production and decay
rates → Expect similar influence on <sv>
NB1: M2 can also be complex, but its phase can be rotated away.
NB2: CPV phases are strongly constrained by dipole moments;
we set fm=0 and assume very heavy 1st+2nd generation sfermions
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WHEPP-9 Bhubaneswar
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CP violation: Higgs sector

Non-zero phases induce CP violation in the Higgs sector
through loops → mixing of h,H,A:

Couplings to neutralinos:
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WHEPP-9 Bhubaneswar
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Previous studies
of neutralino relic density with CP violation
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WHEPP-9 Bhubaneswar
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CPV analysis with micrOMEGAs
M1 = 150, M2 = 300, At = 1200 GeV, tanb = 5
masses of 3rd gen: 500 GeV, 1st+2nd gen: 10 TeV




bino-like LSP, m ~ 150 GeV
Wh2 < 0.129 needs annihilation through Higgs
Scenario 1: m = 500 GeV → small mixing in Higgs sector
Scenario 2: m = 1 TeV → large mixing in Higgs sector
Higgs mixing ~ Im(Atm)
[Belanger, Boudjema, SK, Pukhov, Semenov, in: LesHouches‘05]
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WHEPP-9 Bhubaneswar
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CPV with micrOMEGAs
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WHEPP-9 Bhubaneswar
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Scenario 2
Key parameter is distance from pole
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WHEPP-9 Bhubaneswar
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Recall Higgs funnels in mSUGRA
m A=
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WHEPP-9 Bhubaneswar
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Higgs funnel with large Higgs CP-mixing
h2
h3
h3
h3
Green bands: 0.094 < Wh2 < 0.129
dmi = mhi - 2mLSP, i=2,3
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WHEPP-9 Bhubaneswar
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Higgs funnel with large Higgs CP-mixing
h2
h3
h3
h3
Green bands: 0.094 < Wh2 < 0.129
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WHEPP-9 Bhubaneswar
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Higgs funnel with large Higgs CP-mixing
h3
Green bands: 0.094 < Wh2 < 0.129
dmi = mhi - 2mLSP, i=2,3
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WHEPP-9 Bhubaneswar
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
CP violation

is a very interesting option
 can have order-of-magnitude effect on Wh2
 needs to be tested precisely

However: computation of annihilation
cross sections at only at tree level;
radiative corrections may be sizeable!
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WHEPP-9 Bhubaneswar
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Assume we have found SUSY with
a neutralino LSP and made very precise
measurements of all relevant parameters:
What if the inferred
2
Wh is too high?
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WHEPP-9 Bhubaneswar
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Solution 1:
Dark matter is superWIMP
e.g. gravitino or axino
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WHEPP-9 Bhubaneswar
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Solution 2:
R-parity is violated after all

RPV on long time scales

Late decays of neutralino LSP reduce the
number density; actual CDM is something else

Very hard to test at colliders

Astrophysics constraints?
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WHEPP-9 Bhubaneswar
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Solution 3:
Cosmological assumptions are wrong





Our picture of dark matter as a thermal relic
from the big bang may be to simple
The early Universe may have evolved differently
....
....
....
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WHEPP-9 Bhubaneswar
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Conclusions:

We expect new physics beyond the SM



to show up at the TeV energy scale
to provide the dark matter of the Universe
Using the example of neutralino dark matter
I have shown that precison measurements at
both LHC+ILC are necessary to pin down the
nature and properties of the dark matter
Wh2 ~ 1/<sv> from LHC/ILC ↔ WMAP acurracy
 Direct detection in addition to pin down DM
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WHEPP-9 Bhubaneswar
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LHC
WMAP
ILC
Accuracies of determining the LSP mass and its relic density
[Alexander et al., hep-ph/0507214]
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WHEPP-9 Bhubaneswar
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What if only part of the spectrum is
accessible?

Part of the spectrum may escape detection



Too heavy sparticles, only limits on masses
Not enough sensitivity, e.g. H,A
Only LHC data available, ....

Model assumptions, fits of specific models, etc,
to obtain testable predicions [or to test models]

Famous example: Fit of mSUGRA to LHC data at SPS1a
Need precise predictions within models of SUSY breaking
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WHEPP-9 Bhubaneswar
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Comparison of SUSY spectrum codes

Computation of SUSY spectrum with 4 state-of-the-art
SUSY codes: Isjet, Softsusy, Spheno, Suspect
2loop RGEs + 1loop threshold corrections,
1loop corr. to Yukawa couplings, ...

Computation of relic desity with micrOMEGAs

Mapped mSUGRA parameter space for
 differences in predictions of Wh2
 differences in WMAP exclusions
due to spectrum uncertainties
[Belanger, SK, Pukhov, hep-ph/0502079]
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WHEPP-9 Bhubaneswar
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Uncertainties from sparticle mass predictions O(1%)
moderate parameters, stau coannihilation
Stau-LSP mass difference!
d(DM) ~ 1 GeV → dW ~ 10%
Contours of Wh2=0.129
S. Kraml
[Belanger, SK, Pukhov, hep-ph/0502079]
WHEPP-9 Bhubaneswar
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Uncertainties from sparticle mass predictions:
large tanb and the Higgs funnel
[Belanger, SK, Pukhov, hep-ph/0502079]
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WHEPP-9 Bhubaneswar
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
There is need to improve computations
and tools in order to match acurracies
required by WMAP/Planck
Improvements in spectrum computations are discussed
in [Baer, Ferrandis, SK, Porod, hep-ph/0511123]
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WHEPP-9 Bhubaneswar
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