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A Profile Likelihood Analysis of the Constrained MSSM with Genetic Algorithms
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
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2010 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 4, 057- p.Article in journal (Refereed) Published
Abstract [en]

The Constrained Minimal Supersymmetric Standard Model (CMSSM) is one of the simplest and most widely-studied supersymmetric extensions to the standard model of particle physics. Nevertheless, current data do not sufficiently constrain the model parameters in a way completely independent of priors, statistical measures and scanning techniques. We present a new technique for scanning supersymmetric parameter spaces, optimised for frequentist profile likelihood analyses and based on Genetic Algorithms. We apply this technique to the CMSSM, taking into account existing collider and cosmological data in our global fit. We compare our method to the MultiNest algorithm, an efficient Bayesian technique, paying particular attention to the best-fit points and implications for particle masses at the LHC and dark matter searches. Our global best-fit point lies in the focus point region. We find many high-likelihood points in both the stau co-annihilation and focus point regions, including a previously neglected section of the co-annihilation region at large m 0. We show that there are many high-likelihood points in the CMSSM parameter space commonly missed by existing scanning techniques, especially at high masses. This has a significant influence on the derived confidence regions for parameters and observables, and can dramatically change the entire statistical inference of such scans.

Place, publisher, year, edition, pages
2010. no 4, 057- p.
Keyword [en]
High Energy Physics - Phenomenology, Astrophysics - Cosmology and Extragalactic Astrophysics
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:su:diva-38220DOI: 10.1007/JHEP04(2010)057ISI: 000277473100013OAI: oai:DiVA.org:su-38220DiVA: diva2:308045
Available from: 2010-04-01 Created: 2010-04-01 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Searches for Particle Dark Matter: Dark stars, dark galaxies, dark halos and global supersymmetric fits
Open this publication in new window or tab >>Searches for Particle Dark Matter: Dark stars, dark galaxies, dark halos and global supersymmetric fits
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The identity of dark matter is one of the key outstanding problems in both particle and astrophysics. In this thesis, I describe a number of complementary searches for particle dark matter. I discuss how the impact of dark matter on stars can constrain its interaction with nuclei, focussing on main sequence stars close to the Galactic Centre, and on the first stars as seen through the upcoming James Webb Space Telescope. The mass and annihilation cross-section of dark matter particles can be probed with searches for gamma rays produced in astronomical targets. Dwarf galaxies and ultracompact, primordially-produced dark matter minihalos turn out to be especially promising in this respect. I illustrate how the results of these searches can be combined with constraints from accelerators and cosmology to produce a single global fit to all available data. Global fits in supersymmetry turn out to be quite technically demanding, even with the simplest predictive models and the addition of complementary data from a bevy of astronomical and terrestrial experiments; I show how genetic algorithms can help in overcoming these challenges.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2010. 84 p.
Keyword
dark matter, supersymmetry, gamma rays, dwarf galaxies, stellar evolution, cosmological perturbations, phase transitions, statistical techniques
National Category
Subatomic Physics Subatomic Physics Astronomy, Astrophysics and Cosmology Subatomic Physics Other Physics Topics Astronomy, Astrophysics and Cosmology Astronomy, Astrophysics and Cosmology
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-38221 (URN)978-91-7447-031-4 (ISBN)
Public defence
2010-05-04, FD5, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 15:15 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Accepted. Paper 6: Submitted. Available from: 2010-04-12 Created: 2010-04-01 Last updated: 2010-04-07Bibliographically approved
2. 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

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