Constraining CMSSM dark matter with direct detection results
Chris SavageOskar Klein Centre for Cosmoparticle Physics
Stockholm University
with Yashar Akrami, Pat Scott, Jan Conrad & Joakim EdsjöJCAP 1104:012, 2011 [arXiv:1011.4318]JCAP 1107:002,2011 [arXiv:1011.4297]
Overview
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Direct detection signalN, Ek=1..N , Sm, , , ...
WIMP parameters m , SI,p , SD,p , SD,n
Direct detection signalN, Ek=1..N , Sm, , , ...
CMSSM (e.g.) parameters m0, m1/2, A0, tanβ, sign(μ)
WIMP parameters m , SI,p , SD,p , SD,n
Phenomenology Particle (SUSY) TheoryMessy parameter space:
statistical scanning requiredWell behaved parameter space:
analytical methods for constraints?
Pheno space notfully mapped out
by CMSSM
This talkExperimental groupsJi-Haeng Huh talk
Overview
• How will future direct detection results constrain dark matter from supersymmetric theories?
Realistic reconstruction of dark matterproperties using CMSSM as case study
• Outline Basics: CMSSM, direct detection Analysis: likelihoods, statistics and scanning Phenomenological parameter constraints
• Individual/combined experimental results• Statistical/scanning issues• Halo model, hadronic uncertainties
CMSSM parameter constraints9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Basics andAnalysis Procedure
Basics
CMSSM (Constrained Minimal Supersymmetric Standard Model) Simplest SUSY model: four parameters + one sign Complicated parameter space: disconnected regions, sharp peaks,… Results/issues representative of generic SUSY models
(e.g. MSSM-7, BMSSM, NMSSM, etc.)
Direct detection:future ton-scale experiments XENON1T (Xe, neutron odd) [LUX, PANDA-X] CDMS1T (Ge, neutron odd) [EDELWEISS, CRESST?] COUPP1T (CF3I, proton odd)
Not included: CoGeNT, CDEX, DAMA, KIMS -like (higher backgrounds)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
DetectorWIMP
WIMPScatter
Analysis
Realistic analysis Typical thresholds and efficiencies Finite energy resolution Backgrounds at target levels (~ 2 events), known spectrum Uncertainties in halo model (density, velocity distribution) Hadronic uncertainties: WIMP-quark → WIMP-nucleon couplings
Likelihoods Direct detection
Nuisance parameters Halo model Nucleon structure SM parameters
…also physicality constraints9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
See paper for technical details
COUPP: no spectrum
Number of events (Poisson) Event energies (spectrum)
Analysis
Procedure Select CMSSM models that give particular m and SI,p :
benchmark models Generate random experimental results Reconstruct CMSSM model by scanning
over CMSSM parameter space• DarkSUSY + SuperBayeS (MultiNest)
Statistics Scan: Bayesian (SuperBayes) Results: Frequentist or Bayesian
• Profile likelihood (frequentist)• Marginalized PDF (Bayesian)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
www.darksusy.orgwww.superbayes.org
Most experimental analyses
Benchmark Models
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
BM1: low m , high SI,p O(100-400) signal events
BM2: low m , low SI,p O(1-3) signal events
BM3: moderate m and SI,p O(20-30) signal events
BM4: high m , high SI,p O(20-30) signal events
+ 2 background events (on average)
Benchmarks still below most recent XENON constraints
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Results(Constraints)
BM1: low m , high SI,p
Spin-independent/dependent cross-sections vs. mass XENON: ~ 200 signal events (~ 7 SD events)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
true value max likelihood posterior mean
BM1: low m , high SI,p
Spin-independent/dependent cross-sections vs. mass CDMS: ~ 140 signal events (~ 2 SD events)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
BM1: low m , high SI,p
Spin-independent/dependent cross-sections vs. mass COUPP: ~ 390 signal events (~ 120 SD events)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
BM1: low m , high SI,p
Spin-dependent couplings: neutron vs. proton an ≈ -ap : CMSSM prediction (not experimental constraint) O(5) [CDMS/XENON] vs. O(100) [COUPP] SD events
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
BM2: low m , low SI,p
Spin-independent/dependent cross-sections vs. mass ~ 1.4 / 2.1 / 3.0 signal events (~ 0 / 0 / 0.1 SD)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
BM3: moderate m and SI,p
Spin-independent/dependent cross-sections vs. mass ~ 17 / 23 / 32 signal events (~ 0 / 0 / 0.6 SD)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
BM4: high m , high SI,p
Spin-independent/dependent cross-sections vs. mass ~ 19 / 25 / 36 signal events (~ 0 / 0 / 0.3 SD)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Issues
Issue: sampling/coverage Mass constraint from energy spectrum:
degeneracy for heavy WIMPs
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Phenomenological parameter scanPato et al., PRD 83, 083505 (2011)
BM3
BM4
Issue: sampling/coverage
• Scan points without DD likelihood BM4 in poorly sampled region BM3 in higher sampled region
• Degeneracy: BM3 & BM4 should give
similar DD signals (N, Ei)
• BM4 scan: Good fit around BM3 Nothing to draw scan towards
BM4 region Too few models to properly
evaluate profile likelihood9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Issue: sampling/coverage
• Real priors and/or effective priors affect scan region
• Scan may miss some regions of interest or cover them too coarsely
• Can lead to significant over/under-coverage of confidence regions (frequentist) or credible regions (Bayesian)
• Possibly improved by higher statistics …if higher statistics gives sharper likelihood contours
(can overcome real/effective priors) Not for previous case
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Issue: nuisance parameters
• Halo model Local density, velocity distribution Standard Halo Model (SHM): isothermal sphere
• 3 velocity parameters: v0, vobs, vesc
Structure?• Annual modulation (DAMA, CoGeNT)• Directional detection (DRIFT)
• Hadronic matrix elements Used in calculating SI & SD from -quark couplings 6 relevant matrix elements (only 3 are important) Affect CMSSM constraints, not pheno constraints (at least not
directly)9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Halo models + direct detection:see Strigari & Trotta (2009)
and various works by A. Green
See Ellis, Olive & CS, PRD 77, 065026 (2008)
Halo model uncertainties
With / without uncertainties in halo model (nuisance parameters) Local DM density most significant
• See e.g. Strigari & Trotta, JCAP 11, 019 (2009)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
Hadronic uncertainties
With / without hadronic uncertainties (nuisance parameters) No change: affects only CMSSM parameter constraints
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
Hadronic uncertainties
With / without hadronic uncertainties (nuisance parameters) Only directly affects CMSSM parameter constraints
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
CMSSMConstraints
CMSSM constraints
No direct detection likelihood (priors and nuisance only)
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
CMSSM constraints (BM1)
With direct detection likelihood Gaugino mass (m1/2) best constrained (related to m) Weaker constraints on m0, A0, tanβ
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
Profile likelihood: ■ 1σ ■ 2σ
CMSSM constraints
• Can combine with other observational data: Indirect detection: cosmic-rays, neutrinos Accelerators Relic density, etc.
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
-rays (Fermi-LAT)Segue 1 analysisScott et al. (2009)
Neutrinos (IceCube)IC collab + Edsjö, Scott, CS, in prep.
Accelerator (LHC: ATLAS)SU3 benchmark analysis
Bridges et al. (2010)
See Trotta et al., JHEP 0812:024 (2008)
Summary
• Examined realistic reconstruction of darkmatter properties in SUSY (e.g. CMSSM)theories using direct detection results
• Can reconstruct WIMP properties reasonablywell in some cases, not so well in others Coverage, sampling issues:
Accuracy affected by scanning technique Nuisance parameters
• Combine DD results with other observationsto better constrain SUSY theory parameters
9/27/2011 C Savage - DSU 2011 - CMSSM and Direct Detection
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