Neutralino dark matter detection around the corner?Neutralino dark matter detection around the corner? Status and prospects in the Constrained MSSM Roberto Trotta Oxford Astrophysics

Neutralino dark matter detection Neutralino dark matter detection around the corner?around the corner?

Status and prospects Status and prospects in the Constrained MSSMin the Constrained MSSM

Roberto TrottaOxford Astrophysics & Royal Astronomical Society

With Roberto Ruiz de Austri (Madrid) & Leszek Roszkowsky (Sheffield)

Fritz ZwickyAndromeda (M31)

Sir Isaac Newton

The dark side of the Universe

Newton

Observations

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What is the Universe made of?What is the Universe made of?

Dark energy70%

Dark matter25%

Stars,planets,human beings,...

Gas

Neutral, stable, cold ΩCDMh2 = 0.103 ± 0.009 (WMAP3)

A well motivated candidate:Lightest Supersymmetric Particle

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SUSY frameworkSUSY framework

Lightest SUSY particle: the neutralinoχ0 = lightest mass eigenstate of

quarks squarks

R = +1 R = -1

leptons sleptons

gauge bosons gauginosHiggs higgsinos

χ0 Forbiddenby R-parity

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WIMP relic densityWIMP relic density

Ωχ h2 ∼ 1/<σv>

(1) Thermal equilibrium(2) Pair annhililation(3) Γ << H : freee out

Relic abundance

Mass mχ ≈ 0.4 m1/2∼ 0.1 – 1 TeV

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The Constrained MSSMThe Constrained MSSM

General MSSM scenario: soft SUSY breaking> 120 free parameters in the Lagrangian

Assuming Universal boundary conditions at MGUT

Gaugino masses: M1 = M2 = M3 = m1/2

Scalar masses: mHd

2 = mHu2 = ML

2 = MR2= MQ

2 = MD2= MU

2 =m02

Trilinear couplings Au = Ad = Al = A0

Higgs vev ratio tanβ = vu/vd

A 4 parameters benchmark scenario(m1/2, m0, A0, tanβ)

2D slices of CMSSM parameter space2D slices of CMSSM parameter space

(Nihei, Roszkowski, Ruiz de Austri 2002)

But this is only for fixed A0, tanβ, mt, mb,....

mmbb = 4.0 GeV m= 4.0 GeV mbb = 4.5 GeV= 4.5 GeV

Uncertainty in SM parameters cannot be neglected (Roszkowski, Ruiz de Austri, Nihei 2001)

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Bayesian parameter estimationBayesian parameter estimation

Bayes’ Theorem

prior

posterior

likelihood

θPr

obab

ility

den

sity

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Bayes + Monte Carlo Markov ChainBayes + Monte Carlo Markov Chain

MCMC: a procedure to draw samples from the posterior pdf

MCMC Bayesian Frequentist

Efficiency ∝ N ∝ kN

Nuisance params YES undefined

Marginalization trivial close to impossible

Derived params YES need estimator

Prior information YES undefined

Model comparison YES significance tests only

Theoretical uncert’ies YES only simplistic

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A full 8D Bayesian analysisA full 8D Bayesian analysis

CMSSM parameters

Nuisance (SM) parameters

Collider observablesSUSY mass limits (LEPII), Higgs limits, BR’s, g-2, EW observables

Cosmological CDM abundance(WMAP1 + others)

Roberto Ruiz de Austri (Madrid), RTLeszek Roszkowski (Sheffield) JHEP 05 (2006) 002, hep-ph/0602028

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Direct DM detection in the CMSSMDirect DM detection in the CMSSM

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Direct searches: present & futureDirect searches: present & future

Courtesy Hans Kraus

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Direct DM detection in the CMSSMDirect DM detection in the CMSSM

1 event/kg/yre.g. EDELWEISS IICRESST II

1 event/ton/yrEURECA

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Sensitivity to assumptionsSensitivity to assumptions

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DD

Complementarity with LHCComplementarity with LHC

Ruiz, Trotta, Roszkowski (2006)

LHC

LHC

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SUSY @ LHC?SUSY @ LHC?Pr

obab

ility

den

sity

4 TeV prior2 TeV prior 4 TeV prior, no g-2

Inte

gra

ted p

robab

ility Eg,

gluino mass< 2.7 TeVwith78% prob.

ROBUST

Sleptons, squarks: prior and g-2 dependent

Probab

ility

den

sity

Inte

gra

ted p

robab

ility

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Final remarksFinal remarksBAYESIAN FRAMEWORK + MCMC

Powerful, flexible tool for statistical inferenceHandles effortlessly marginalization, nuisance & derived params, theoretical errors,...

CONSTRAINED MSSM LSP well motivated DM candidateHighly predictive frameworkCareful treatment of uncertainties necessary

OBSERVATIONAL PROSPECTS CMSSM neutralino dark matter: direct detection possible by the end of the decadeDM search complementary to collider SUSY searches Null result: easy to accomodate in the general MSSM, but...

“Squarks, sleptons, dark matter, dark energy.All those damn particles you can’t see.

That’s what drove me to drink. But now I can see them!”