SUSY Dark Matter Collider – direct – indirect search bridge.

Sabine KramlLaboratoire de Physique Subatomique et de Cosmologie

Grenoble, France

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43. Rencontres de Moriond

La Thuile, 1-8 March 2008

Moriond EW 2008 2S. Kraml: SUSY dark matter

WIMP paradigm DM should be stable, electrically neutral,

weakly and gravitationally interacting

WIMPs ― weakly interacting massive particles

WIMPs are predicted by most theories beyond the Standard Model (BSM)

Stable as result of discrete symmetries

Thermal relic of the Big Bang

Testable at colliders!

Neutralino, gravitino, axino, lightest KK state, T-odd little Higgs, etc., ...

BSM-DM

c.f. talk by M. Tytgat

Moriond EW 2008 3S. Kraml: SUSY dark matter

let‘s go SUSY ...

Moriond EW 2008 4S. Kraml: SUSY dark matter

What is SUSY? Supersymmetry (SUSY) is a symmetry between fermions and bosons.

The SUSY generator Q changes a fermion into a boson & vice versa

Extension of space-time to include anticommuting coordinates

x → (x, ) with

This combines the relativistic “external” symmetries (such as Lorentz invariance) with the “internal” symmetries such as weak isospin.

Actually the unique extension of the Poincare algebra *

* (the algebra of space-time translations, rotations and boosts)

Moriond EW 2008 5S. Kraml: SUSY dark matter

space-time symmetry

(special relativity)

Antiparticles

space-time

supersymmetry

Superpartners

doubling of

the spectrum

Moriond EW 2008 6S. Kraml: SUSY dark matter

The beauties of SUSY Unique extension of relativistic symmetries

Solution to gauge hierarchy problem

Radiative EW symmetry breaking, light Higgs

Gauge coupling unification

Ingredient of string theories

Very rich collider phenomenology

Cold dark matter candidate ....

Moriond EW 2008 7S. Kraml: SUSY dark matter

SUSY as a local gauge theory includes a spin-2 state,

the graviton (!) and its superpartner the gravitino.

Minimal Supersymmetric Standard Model(MSSM)

gluino

2 charginos ±

4 neutralinos

If SUSY comes with a new conserved parity, RP,

then the lightest SUSY particle (LSP) is stable

DARK MATTER CANDIDATE

Gravitino, sneutrino or

lightest neutralino

Moriond EW 2008 8S. Kraml: SUSY dark matter

I am concentrating on the neutralino case.

For gravitino DM, see talk by F. Steffen tomorrow morning

Moriond EW 2008 9S. Kraml: SUSY dark matter

SUSY searches at the LHC

CMS

Moriond EW 2008 10S. Kraml: SUSY dark matter

01

Z

q

q

02

q~g~

jet

jet

jets, l+l−

missing energy

Large cross sections ~100 events/day for M ~ 1 TeV

Spectacular signatures SUSY could be found early on

gggqqq ~~ ,~~ ,~~

Cascade decays into LSP

lead to typical signature:

multi-jets / multi-leptons

plus large missing energy

SUSY @ LHC

Every SUSY event → 2 LSPs.

Abundant production!

LHC as DM factory

Moriond EW 2008 11S. Kraml: SUSY dark matter

Mass measurements: cascade decaysET

miss → no peaks → mass reconstruction through kinematic endpoints

[ATLAS, G. Polesello]

Typical precisions: a few %

Moriond EW 2008 12S. Kraml: SUSY dark matter

Neutralino annihilation:

LSP as thermal relic: relic density computed as thermally avaraged

cross section of all annihilation channels → h2 ~ v −1

Moriond EW 2008 13S. Kraml: SUSY dark matter

Consequences

1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant

CMSSM: GUT-scale

boundary conditions:

m0, m1/2, A0,

plus tanb, sgn()

Moriond EW 2008 14S. Kraml: SUSY dark matter

Consequences

1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant

good h2

Simple SO(10) SUSY GUTs:

dual requirement of Yukawa

unification and DM relic density

is extremley predictive

→ Very distinct LHC signatures:

~500-600 GeV gluinos

50-75 GeV 1

talk by S. Sekmen in YSF2

Moriond EW 2008 15S. Kraml: SUSY dark matter

Consequences

1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant

2. If we can measure the properties of the SUSY particles precisely enough, then we can compute v of the LSP

→ „collider prediction“ of h2

→ compare with cosmological observations

Note: this means measuring (or at least putting limits on)

masses and couplings of most of the SUSY spectrum to infer

Moriond EW 2008 16S. Kraml: SUSY dark matter

Consequences

1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant

2. If we can measure the properties of the SUSY particles precisely enough, then we can compute v → h2

3. We can also compute the direct and indirect

detection rates

direct detection: m, Nv, local DM density

indir. det.: <v >v→0, density profile, propagation model

Moriond EW 2008 17S. Kraml: SUSY dark matter

However, uncertainties in N calculation are large (~50%)

Direct detection: limits and predictions

Xenon10new CDMS result!

Predictions of various SUSY models

Moriond EW 2008 18S. Kraml: SUSY dark matter

Indirect searches:high energetic positrons or gamma rays from annihilation

Moriond EW 2008 19S. Kraml: SUSY dark matter

Indirect detection: EGRET signal?

[W. DeBoer, arXiv:0711.1912]

50–70 GeV neutralino?EGRET

Moriond EW 2008 20S. Kraml: SUSY dark matter

Higgs?

SUSY?

1 GeV ~ 1.3 * 1013 K

„It is impossible to overestimate the importance of discovering dark matter at the LHC. Such a discovery will imply a revision of the SM, it will strenghten the connection between particle physics, cosmology and astrophysics, and it will enormously enlarge our understanding of the present and past universe.“

G.F. Giudice, Theories for the Fermi Scale (2007)