Supersymmetric dark matter Neutralinos Gravitinos

1
Supersymmetric dark matterNeutralinos -
Gravitinos

• David G. Cerdeño
• Institute for Particle Physics Phenomenology

Based on works with S.Baek, K.Y.Choi, C.Hugonie,
K.Jedamzik, Y.G.Kim, P.Ko, D.López-Fogliani,
C.Muñoz, R.R. de Austri, L.Roszkowski,
A.M.Teixeira
2
Contents

• Present status
• Dark matter is a necessary ingredient in present
  models for the Universe
• but we have not identified it yet
• Can it be the Lightest Supersymmetric Particle
  (LSP)?
• Direct detection experiments will continue
  providing data in the near future.
• It may be detected in running or projected dark
  matter experiments?
• The lightest Neutralino?
• Or maybe not?
• The gravitino (or the axino)?

05-06-06 Sussex
3
Dark Matter

• The motivation for dark matter arises from
  gravitational effects in astronomical
  observations at various scales

Coma Cluster

• Analyses of the CMB are also consistent with the
  existence of large amounts of Dark Matter

05-06-06 Sussex
4
Dark Matter

• We have an idea of what we are looking for

• But the number of suspects is large

Axions with a small mass ma?10-5 eV
Weakly Interacting Massive Particles (WIMPS)
Lightest Supersymmetric Particle
Lightest Kaluza-Klein Particle
SIMPs, CHAMPs, SIDM, WIMPzillas, Scalar DM, Light
DM

• and may have an alibi

Modified Newtonian Dynamics (MOND) can also
explain galactic rotation curves
05-06-06 Sussex
5
Lightest Supersymmetric Particle

• The LSP is stable in SUSY theories with
  R-parity. Thus, it will exist as a remnant from
  the early universe and may account for the
  observed Dark Matter.

In the MSSM, the LSP can be
Lightest squark or slepton charged and therefore
excluded by searches of exotic isotopes
Lightest sneutrino They annihilate very quickly
and the regions where the correct relic density
is obtained are already experimentally excluded
Lightest neutralino WIMP
Gravitino Present in Supergravity theories. Can
also be the LSP and a good dark matter candidate
Axino SUSY partner of the axion. Extremely weak
interactions
05-06-06 Sussex
6
Contents

• Neutralino dark matter (prospects for its direct
  detection)
• General Supergravity theories (MSSM and NMSSM)
• SUGRA from string theories (Heterotic string)
• Gravitino dark matter (analysis of the parameter
  space of the CMSSM)
• Big Bang Nucleosynthesis and Charge and
  Colour-Breaking constraints.

05-06-06 Sussex
7
SUSY dark matter

• The lightest Neutralino
• General SUGRA

05-06-06 Sussex
8
Neutralino dark matter

• The lightest Neutralino is a very well motivated
  dark matter candidate it is a WIMP and could be
  observed in direct detection experiments

Direct detection through the elastic scattering
of a WIMP with nuclei inside a detector.
Many experiments around the world are currently
looking for this signal with increasing
sensitivities
How large can the neutralino detection cross
section be?
Could we explain a hypothetical WIMP detection
with neutralino dark matter?
05-06-06 Sussex
9
The lightest Neutralino

• In the MSSM the mechanisms which allow for an
  increase in the detection cross section are well
  known

In the MSSM, the neutralino is a physical
superposition of the B, W, H1, H2
The detection properties of the neutralino depend
on its composition
05-06-06 Sussex
10
Neutralinos in SUGRA theories

• How large can the direct detection cross section
  for neutralinos be in Supergravity theories?

1) The Soft supersymmetry-breaking terms are
taken as inputs at the GUT scale and RGE are used
to evaluate the SUSY spectrum
2) Experimental constraints are applied on the
parameter space masses of superpartners
Low energy observables ( (g-2)m , b?sg, BS ?
mm-, )
3) Constraint on relic density
05-06-06 Sussex
11
Charge and Colour breaking
The presence of scalar fields with Colour or
Electric charge in SUSY theories may induce the
occurrence of dangerous charge and
colour-breaking minima, deeper than the realistic
vacuum
V
The UFB-3 direction, where
Hu
take non-vanishing VEVs is the deepest one
Realistic Minimum
Charge and/or Colour-breaking minimum
Light sleptons ? stronger constraints
The potential along the UFB-3 direction reads
05-06-06 Sussex
12
mSUGRA

• For example, in the Constrained MSSM (universal
  soft terms) the allowed parameter space is very
  limited

05-06-06 Sussex
13
mSUGRA

• For example, in the Constrained MSSM (universal
  soft terms) the allowed parameter space is very
  limited

Only those regions allowing for a reduction of
the neutralino relic density are left

• Coannihilations with NLSP
• Rapid annihilation due to resonance with CP-odd
  Higgs
• Focus Point

05-06-06 Sussex
14
mSUGRA

• For example, in the Constrained MSSM (universal
  soft terms) the allowed parameter space is very
  limited

The resulting neutralino detection cross section
is very small.
Departures of the CMSSM allow an increase of the
cross section
05-06-06 Sussex
15
Large detection cross sections

• The scalar part of the cross section has two
  contributions

Squark-exchange
Higgs-exchange
Leading contribution. It can increase when

• The Higgsino components of the neutralino
  increase

• The Higgs masses decrease

05-06-06 Sussex
16
Large detection cross sections
Higgs-exchange
Leading contribution. It can increase when

• The Higgsino components of the neutralino
  increase

• The Higgs masses decrease

In terms of the mass parameters in the RGE
mHd2
Non-universal soft terms (e.g., in the Higgs
sector)
MGUT
mHu2
mHu2 ?
mHd2 ?
05-06-06 Sussex
17
Large detection cross sections
Higgs-exchange
Leading contribution. It can increase when

• The Higgsino components of the neutralino
  increase

• The Higgs masses decrease

In terms of the mass parameters in the RGE
mHd2
Non-universal soft terms (e.g., in the Higgs
sector)
MGUT
MI
mHu2
mHu2 ?
Or intermediate scales
mHd2 ?
05-06-06 Sussex
18
Large detection cross sections
Extensions of the MSSM also allow an increase of
the Higgs-exchange amplitude. For instance, in
the Next-to-MSSM, where a new singlet (and
singlino) is included
Higgs-exchange
Leading contribution. It can increase when

• The Higgsino components of the neutralino
  increase

• The Higgs masses decrease

05-06-06 Sussex
19
Non-universal soft terms

• Example with non-universal Higgs masses at the
  GUT scale

2
(S.Baek, D.G.C., G.Y.Kim, P.Ko, C.Muñoz04)
05-06-06 Sussex
20
Non-universal soft terms

• With non-universalities in both the scalar and
  gaugino sectors neutralinos in the detectable
  range can be obtained with masses of order 10-500
  GeV

Very light Bino-like neutralinos with masses 10
GeV.
Heavy Higgsino-like neutralinos with masses 500
GeV.
05-06-06 Sussex
21
Next-to-MSSM

• Very large detection cross sections can be
  obtained for singlino-line neutralinos

This is due to the Higgs masses being very small.
These results correspond to Higgses lighter than
70 GeV and mostly singlet-like
The relic density for these neutralinos is still
to be calculated.
(D.G.C., C.Hugonie, D.López-Fogliani, A.Teixeira,
C.Muñoz 04)
05-06-06 Sussex
22
SUSY dark matter

• The lightest Neutralino
• General SUGRA
• SUGRA from Heterotic string theory

05-06-06 Sussex
23
Neutralinos in SUGRA theories

• How large can the direct detection cross section
  for neutralinos be in Supergravity theories?

1) The Soft supersymmetry-breaking terms are
taken as inputs at the GUT scale and RGE are used
to evaluate the SUSY spectrum
2) Experimental constraints masses of
superpartners Low energy observables (
(g-2)m , b?sg, BS ? mm-, )

• String scenarios provide explicit realisations
  of SUGRA theories at the low-energy limit.
• The soft terms are given in terms of the moduli
  fields, which characterise the size and shape of
  the compactified space.
• The number of free parameters is greatly reduced
• Are large neutralino detection cross sections
  still possible?

3) Constraint on relic density
05-06-06 Sussex
24
Heterotic Orbifolds

• After compactification of the Heterotic
  Superstring on a 6-dimensional orbifold, the
  resulting 4D Supergravity is described by

From which the soft terms are calculated

• The breaking of SUSY is due to the auxiliary
  fields of the dilaton (S) and moduli (Ti) fields
  developing a VEV. A convenient parameterisation
  of these is

The Goldstino angle, , determines which is the
field responsible for the breaking of SUSY.
05-06-06 Sussex
25
Heterotic Orbifolds

• As a function of the gravitino mass, , the
  Goldstino angle, , and the modular weights,
  , the soft masses read

• Few free parameters,
• Non-universal scalar masses, in general, due to
  the effect of the modular weights
• Gaugino masses larger than scalar masses, Mgtmi

05-06-06 Sussex
26
Heterotic Orbifolds

• In the heterotic superstring successful
  unification of the gauge couplings at
  MGUT ? 2x1016 GeV is not automatic.
• Instead, unification would take place at energies
  around MHET ? 5x1017 GeV .

MGUT
MHET
Large one-loop threshold corrections are needed
in order to alter the RGEs and regain
unification. These corrections can be obtained
for particular choices of the modular weights of
the fields.
(Ibáñez, Lüst, Ross 91)
05-06-06 Sussex
27
Heterotic Orbifolds
The simplest possibility corresponds to the
following choice of modular weights
(Ibáñez, Lüst, Ross 91)
For instance, with
Non-universalities grow, away from the dilaton
limit
Dilaton-dominated SUSY
05-06-06 Sussex
28
Heterotic Orbifolds
Dilaton-limit
Excluded by UFB constraints

• The smallness of the slepton masses implies
  strong UFB constraints. Most of the parameter
  space is excluded for this reason.

05-06-06 Sussex
29
Heterotic Orbifolds
Excluded by UFB constraints

• The smallness of the slepton masses implies
  strong UFB constraints. Most of the parameter
  space is excluded for this reason.

• For larger values of tanb the UFB constraints
  become more stringent and the whole parameter
  space is disfavoured

05-06-06 Sussex
30
Heterotic Orbifolds

• Even if we ignored the effect of the UFB
  constraints, the predictions for neutralino
  direct detection are very pessimistic.
• The neutralino is mostly Bino.

05-06-06 Sussex
31
Optimised Case
We can think of an optimised case in which the
slepton masses are increased in order to avoid
UFB constraints
05-06-06 Sussex
32
Optimised Case
Due to the increase of the stau mass, the region
excluded due to tachyons is reduced. Also, the
UFB constraints are less stringent.
Allowed region
Excluded by UFB constraints

• Some regions allowed by the UFB constraints for
  tanb ? 30

05-06-06 Sussex
33
Optimised Case
We can think of an optimised case in which the
slepton masses are increased in order to avoid
UFB constraints
EDELWEISS
CDMS Soudan
GEDEON
CDMS Soudan
GENIUS

• Some regions allowed by the UFB constraints for
  tanb ? 30
• The predictions for are still small.
  Due to the smallness of the neutralino is
  Bino-like

05-06-06 Sussex
34
Other cases

• We have completed the analysis with other
  possible scenarios leading to unification of the
  gauge couplings with the same qualitative results.

• The non-universalities are always negative
  (negative modular weights)

Slepton masses are typically very small, thus
leading to stringent UFB constraints
The Higgs mass parameter cannot be
efficiently increased, implying low
05-06-06 Sussex
35
D-term contribution

• An anomalous U(1) is usually present in
  Heterotic string compactifications.

Although its anomaly is cancelled by the
Green-Schwartz mechanism, it generates a
Fayet-Ilioupoulos contribution to the D-term.
Some scalar fields develop large VEVs in order to
cancel the FI term.
This generates and additional non-universality
among the scalar masses, which depends on their
U(1) charges (qi)
The non-universality can be large, even in the
dilaton limit

• Increase m? and help avoiding UFB constraints

It can even be positive if

• Increase mHu and help increasing the neutralino
  detection cross section

05-06-06 Sussex
36
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if
For example, using the previous modular weights
but assuming
Large positive non-universality
05-06-06 Sussex
37
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if
For example, using the previous modular weights
but assuming

• Most of the parameter space allowed by UFB
  costraints
• Larger values of tanb are permitted

• Correct relic density without the need of
  coannihilations (smaller pseudoscalar mass)

Excluded by UFB constraints
05-06-06 Sussex
38
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if
For example, using the previous modular weights
but assuming
EDELWEISS
CDMS Soudan

• However, the detection cross section does not
  increase much.
• The smallness of implies that the
  neutralino is mostly Bino.

GEDEON
CDMS Soudan
GENIUS
05-06-06 Sussex
39
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if

• Increase mHu and help increasing the neutralino
  detection cross section

For example, assuming now
Large positive non-universality even in the
dilaton limit
05-06-06 Sussex
40
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if

• Increase mHu and help increasing the neutralino
  detection cross section

For example, assuming now

• Thanks to the increase in , the Higgsino
  components of the neutralino increase.
• Large detection cross sections become possible,
  fulfilling all the experimental and astrophysical
  constraints.

05-06-06 Sussex
41
D-term contribution
The non-universality

• Increase m? and help avoiding UFB constraints

Can even be positive if

• Increase mHu and help increasing the neutralino
  detection cross section

• Decrease mHd (and therefore the Higgs masses),
  thus increasing the neutralino detection cross
  section

Or more negative with

• Further decreasing leads to a decrease of
  the Higgs masses and implies an extra increase of

05-06-06 Sussex
42
Summary (so far)
The identification of dark matter is still an
open problem pointing towards physics beyond the
SM, Supersymmetric dark matter being one of the
most attractive possibilities.

• The lightest neutralino in general SUGRA
  theories could explain a hypothetical detection
  of WIMP dark matter in the next generation
  experiments due to non-universalities in the
  scalar masses.

• SUGRA scenarios arising from compactifications
  of the Heterotic String
• The parameter space is very constrained by
  tachyons in the scalar sector, as well as by
  experimental and astrophysical constraints.
• The smallness of the scalars implies stringent
  UFB constraints
• The presence of an anomalous U(1) ameliorates
  the behaviour under UFB constraints and allows
  for larger non-universalities in the Higgs
  sector.
• As a consequence, large neutralino detection
  cross sections can be obtained, within the reach
  of present experiments.

05-06-06 Sussex
43
SUSY dark matter

• The lightest Neutralino
• General SUGRA
• SUGRA from Heterotic string theory
• The Gravitino

05-06-06 Sussex
44
Gravitino dark matter

• The gravitino can be the LSP in Supergravity

The relation between the gravitino mass and the
rest of the soft masses depends on the
SUSY-breaking mechanism
05-06-06 Sussex
45
Gravitino dark matter

• Gravitino production mechanisms

Thermal Production
Non-Thermal Production
NLSP freezes out
Photons, charged leptons
Nucleosynthesis 3He, 4He, D, Li
?
Reheating
time
TR
1s
05-06-06 Sussex
46
Gravitino dark matter

• Gravitino production mechanisms

• Thermal production
• Through scattering processes and an annihilation
  with (s)particles during thermal expansion of the
  Early Universe.
• Non-thermal production
• Through late decays of the NLSP (normally staus
  or neutralinos)

(Bolz, Buchmüller, Plümacher 98)
Note that
The gravitino can be a good dark matter candidate
in regions where
(see, e.g,. Feng et al. 03, 04)
05-06-06 Sussex
47
Gravitino dark matter

• Gravitino production mechanisms

The total relic density may become too large,
especially for large reheating temperatures
(essential for thermal leptogenesis)
05-06-06 Sussex
48
Gravitino dark matter

• Constraints from Big Bang Nucleosynthesis

NLSP decays into gravitinos typically after Big
Bang Nucleosynthesis.
Late decays of the NLSP can generate highly
energetic electromagnetic and hadronic fluxes
which may alter significantly the abundances of
light elements (thus spoiling the success of Big
Bang Nucleosynthesis).
Energy released into EM and HAD showers
Energy of the sleptons
Yield of NLSP
Branching Ratios
05-06-06 Sussex
49
Gravitino dark matter

• Constraints from Big Bang Nucleosynthesis

Neutralino NLSP
Dominant channel (in the CMSSM the neutralino is
almost a purely bino). Contributes to
Electromagnetic fluxes.
Allowed above kinematic thresholds. Contributes
to Hadronic fluxes.
Below the kinematic thresholds, three body
decays, which contribute to Hadronic fluxes need
to be considered.
05-06-06 Sussex
50
Gravitino dark matter

• Constraints from Big Bang Nucleosynthesis

Stau NLSP
Dominant channel. Contributes mainly to
Electromagnetic fluxes.
Three-body decays give contributions to Hadronic
fluxes.
05-06-06 Sussex
51
Gravitino dark matter

• In the CMSSM

Regions of the parameter space appear where the
gravitino is a good dark matter candidate
Correct relic density from only NTP
Correct relic density with TP
(D.G.C., K.Choi, K.Jedamzik, L.Roszkowski, R.Ruiz
de Austri 05)
52
Gravitino dark matter

• In the CMSSM

Neutralino NLSP areas excluded by BBN
constraints. Only part of those with stau NLSP
are left.
Non-thermal production alone not sufficient.
Large contributions from thermal prod. are
necessary.
As long as TR109 GeV sizable regions are found
with correct O
(D.G.C., K.Choi, K.Jedamzik, L.Roszkowski, R.Ruiz
de Austri 05)
53
Gravitino dark matter

• In the CMSSM

Neutralino NLSP areas excluded by BBN
constraints. Only part of those with stau NLSP
are left.
Non-thermal production alone not sufficient.
Large contributions from thermal prod. are
necessary.
UFB
UFB
In the remaining regions the Fermi vacuum is
metastable. The global minimum breaks charge
and/or colour.
(D.G.C., K.Choi, K.Jedamzik, L.Roszkowski, R.Ruiz
de Austri 05)
54
Gravitino dark matter

• In the CMSSM

The same conclusions remain valid in other
examples
UFB
UFB
(D.G.C., K.Choi, K.Jedamzik, L.Roszkowski, R.Ruiz
de Austri 05)
55
Gravitino dark matter

• Very light gravitinos and constraint on TR

For very light neutralinos non-Thermal Production
is negligible
Thermal Production proportional to
(BBN)
(mGgt100 keV)
(D.G.C., K.Choi, K.Jedamzik, L.Roszkowski, R.Ruiz
de Austri 05)
56
Gravitino dark matter

• Phenomenology

Dark matter experiments would not detect anything
(gravitinos are extremely weakly-interacting)
In particle accelerators (LHC) detection of a
(meta)-stable and electrically charged LSP
(stau). (notice that this would also be true for
axino dark matter)
Valuable information could be obtained about the
vacuum structure (are we living in a false
vacuum?) and early Universe cosmology (value of
TR)
05-06-06 Sussex
57
Summary

• The identification of dark matter is still an
  open problem pointing towards physics beyond the
  SM. Supersymmetric dark matter is one of the most
  attractive possibilities with an interesting
  future

• The lightest neutralino (both in the MSSM and
  NMSSM and in SUGRA derived from strings) could
  explain a hypothetical detection of WIMP dark
  matter in the next generation experiments

• Gravitino dark matter would lead to an
  interesting phenomenology
• Charged observable LSP (stau)
• No detection in dark matter experiments
• The Fermi vacuum may be metastable
• Information on the reheating temperature

05-06-06 Sussex