SUSY in the sky: supersymmetric dark matter

David G. CerdeñoInstitute 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

2-12-05 Durham

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)?

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SUSY dark matter

• The lightest Neutralino

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Direct detection of Neutralinos

• Could the lightest neutralino be found 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?

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Neutralinos

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

1) In which theory? (field content, interactions, parameters…)

MSSM NMSSM …

Parameters given at the GUT scale MGUT (e.g., coming from SUGRA theories) or at the EW scale (effMSSM)

2) Effect of experimental constraints?

masses of superpartners

Low energy observables ( (g-2), bs, BS +-, …)

3) Reproduce the correct relic density?

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Neutralinos

• 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

~ ~ ~ ~

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Neutralinos

• Large detection cross sections

Squark-exchange

Higgs-exchange

Leading contribution. It can increase when

• The Higgsino components of the neutralino increase

• The Higgs masses decrease

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Neutralinos

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

mHu2

Non-universal soft terms (e.g., in the Higgs sector)

MGUT mHu2

mHd2

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Neutralinos

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

mHu2

Non-universal soft terms (e.g., in the Higgs sector)

MGUTMI

Or intermediate scales

mHu2

mHd2

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Neutralinos

In a general Supergravity theory (Non-universal soft supersymmetry-breaking terms in the scalar and gaugino sector) the neutralino can be within the reach of dark matter detectors for a wide range of masses.

Very light Neutralinos

Bino-like

Heavy Neutralinos

Bino-Higgsino

M1 << M2, M1 M2

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Neutralinos

• Neutralinos in the NMSSM

In the Next-to-MSSM, the neutralino has a new singlino (S) component.

The detection properties depend on the neutralino composition

~

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Neutralinos

• Large detection cross sections in the NMSSM

Squark-exchange

Higgs-exchange

Leading contribution. It can increase when

• The Higgsino components of the neutralino increase

• The Higgs masses decrease

2-12-05 Durham

Neutralinos

• Large detection cross sections in the NMSSM

Higgs-exchange

Leading contribution. It can increase when

• The Higgsino components of the neutralino increase

Higgses lighter than 70 GeV and mostly singlet-like

The relic density for these neutralinos is still to be calculated.

• The Higgs masses decrease

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SUSY dark matter

• The lightest Neutralino

• The Gravitino

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Gravitinos

• The gravitino can be the LSP in Supergravity

The gravitino mass depends on the SUSY-breaking mechanism

Gravity-mediated

(GMSB)

Anomaly-Mediated

(AMSB)

m3/2 = O(102 – 103 GeV) ~ m, M

m3/2 = O(10-10 – 10-8 GeV) << m, M

m3/2 = O(10-2 – 102 GeV) m, M

m3/2 = O(104 – 105 GeV) >> m, M

< ~

Gauge-Mediated

Gaugino-Mediated

Gravitino LSP

Gravitino LSP in some regions of the parameter space

Gravitino not LSP

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Gravitinos

• 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)

• Constraints from 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).

G~ WG~,ZG~~

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Gravitinos

• In mSUGRA

All the regions where the neutralino is the NLSP are excluded by BBN constraints. Only part of those areas with stau NLSP are left.

In order to obtain the correct relic density of dark matter thermal production alone is not sufficient. Important contributions from non-thermal production are also necessary.

In the remaining regions the Fermi vacuum is metastable. The global minimum breaks charge and/or colour.

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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) 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