Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Statistical coverage for supersymmetric parameter estimation: a case study with direct detection of dark matter
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). (Cosmology, Particle Astrophysics and String Theory)
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). (Cosmology, Particle Astrophysics and String Theory)
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). (Cosmology, Particle Astrophysics and String Theory)
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). (Cosmology, Particle Astrophysics and String Theory)
Show others and affiliations
2011 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, 002- p.Article in journal (Refereed) Published
Abstract [en]

Models of weak-scale supersymmetry offer viable dark matter (DM) candidates. Their parameter spaces are however rather large and complex, such that pinning down the actual parameter values from experimental data can depend strongly on the employed statistical framework and scanning algorithm. In frequentist parameter estimation, a central requirement for properly constructed confidence intervals is that they cover true parameter values, preferably at exactly the stated confidence level when experiments are repeated infinitely many times. Since most widely-used scanning techniques are optimised for Bayesian statistics, one needs to assess their abilities in providing correct confidence intervals in terms of the statistical coverage. Here we investigate this for the Constrained Minimal Supersymmetric Standard Model (CMSSM) when only constrained by data from direct searches for dark matter. We construct confidence intervals from one-dimensional profile likelihoods and study the coverage by generating several pseudo-experiments for two benchmark sets of pseudo-true parameters. We use nested sampling to scan the parameter space and evaluate the coverage for the two benchmarks when either flat or logarithmic priors are imposed on gaugino and scalar mass parameters. We observe both under- and over-coverage, which in some cases vary quite dramatically when benchmarks or priors are modified. We show how most of the variation can be explained as the impact of explicit and implicit priors, where the latter are indirectly imposed by physicality conditions. For comparison, we also evaluate the coverage for Bayesian credible intervals, and (predictably) observe significant under-coverage in those cases.

Place, publisher, year, edition, pages
2011. no 7, 002- p.
Keyword [en]
dark matter theory, dark matter experiments, cosmology of theories beyond the SM, supersymmetry and cosmology
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology Subatomic Physics
Research subject
Theoretical Physics; High Energy Physics; Theoretical Astrophysics
Identifiers
URN: urn:nbn:se:su:diva-57193DOI: 10.1088/1475-7516/2011/07/002ISI: 000297541000003OAI: oai:DiVA.org:su-57193DiVA: diva2:414555
Available from: 2011-05-03 Created: 2011-05-03 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Supersymmetry vis-à-vis Observation: Dark Matter Constraints, Global Fits and Statistical Issues
Open this publication in new window or tab >>Supersymmetry vis-à-vis Observation: Dark Matter Constraints, Global Fits and Statistical Issues
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Weak-scale supersymmetry is one of the most favoured theories beyond the Standard Model of particle physics that elegantly solves various theoretical and observational problems in both particle physics and cosmology. In this thesis, I describe the theoretical foundations of supersymmetry, issues that it can address and concrete supersymmetric models that are widely used in phenomenological studies. I discuss how the predictions of supersymmetric models may be compared with observational data from both colliders and cosmology. I show why constraints on supersymmetric parameters by direct and indirect searches of particle dark matter are of particular interest in this respect. Gamma-ray observations of astrophysical sources, in particular dwarf spheroidal galaxies, by the Fermi satellite, and recording nuclear recoil events and energies by future ton-scale direct detection experiments are shown to provide powerful tools in searches for supersymmetric dark matter and estimating supersymmetric parameters. I discuss some major statistical issues in supersymmetric global fits to experimental data. In particular, I further demonstrate that existing advanced scanning techniques may fail in correctly mapping the statistical properties of the parameter spaces even for the simplest supersymmetric models. Complementary scanning methods based on Genetic Algorithms are proposed.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2011. 142 p.
Keyword
supersymmetry, cosmology of theories beyond the Standard Model, dark matter, gamma rays, dwarf galaxies, direct detection, statistical techniques, scanning algorithms, genetic algorithms, statistical coverage
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology Subatomic Physics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-57194 (URN)978-91-7447-312-4 (ISBN)
Public defence
2011-06-07, room FA32, AlbaNova University Center, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.Available from: 2011-05-12 Created: 2011-05-03 Last updated: 2011-06-28Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Akrami, YasharSavage, ChristopherScott, PatConrad, JanEdsjö, Joakim
By organisation
Department of PhysicsThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
In the same journal
Journal of Cosmology and Astroparticle Physics
Subatomic PhysicsAstronomy, Astrophysics and CosmologySubatomic Physics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 91 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf