Book/Dissertation / PhD Thesis

PUBDB-2018-04509

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Supersymmetry parameter determination at the International Linear Collider

Lehtinen, S.-L. (Corresponding author)DESY* ; List, J. (Thesis advisor)DESY* ; Sander, C. (Thesis advisor)DESY*

2018
Verlag Deutsches Elektronen-Synchrotron Hamburg

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Please use a persistent id in citations: doi:10.3204/PUBDB-2018-04509

Report No.: DESY-THESIS-2018-035

Abstract: In this thesis, the prospects for determining supersymmetry parameters from observationsof supersymmetric particles at the International Linear Collider (ILC) areinvestigated. Supersymmetry (SUSY) has been proposed in order to solve gaps inthe Standard Model of particle physics, among them the hierarchy problem and theunexplained dark matter content in the universe. There are many free parameters insupersymmetry, whose values give rise to the properties of the supersymmetric particleswhich can be searched for by experiments. While the Large Hadron Collider (LHC)has successfully excluded many possible scenarios, regions of parameter space remainunexplored, especially where the supersymmetric particles decay with little visible energy.For example, models with light higgsinos or scalar tau coannihilation can escapedetection at the LHC. These kinds of scenarios could be discovered or excluded by theproposed ILC, which would collide polarised electron and positron beams at the centreof-mass energy of 500 GeV. The advantages of this machine over the LHC, namely itsthe clean experimental environment and triggerless detector operation, would allow forthe discovery of almost any particle within its kinematic reach.If supersymmetric discoveries were made at the ILC, it would be possible to measurethe properties of the SUSY particles very precisely. These measurements enable determiningsome of the underlying SUSY parameters via tting the parameters to theSUSY observations. In this thesis, a 10-parameter or 13-parameter phenomenologicalMinimal Supersymmetric Standard Model and high-scale 4-6-parameter models(CMSSM, NUHM1 and NUHM2) are tted to sets of possible observations from theILC. Two types of scenarios are considered: light higgsinos motivated by naturalness,and scalar tau coannihilation motivated by the dark matter relic density. It is shownthat the precision measurements of the SUSY and Higgs sectors allow for determiningsome of the SUSY parameters. Additionally, strong predictions for unobserved heavyparticle masses can be made, leading to guidance on future high-energy particle colliders.Furthermore, it is possible under certain circumstances to check whether theobserved particles explain the dark matter relic density. It is shown that the permilleor percent-level measurements from the International Large Detector are crucial formaking these predictions. Additionally, the determined parameters in the weak scalets are evolved to the GUT scale to test the gaugino mass unication hypothesis. Theresults give a strong argument for building an electron-positron collider to close thegaps in the LHC searches or to study any particles that the latter nds.

Note: Dissertation, Universität Hamburg, 2018

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Contributing Institute(s):

1. Experimente an Lepton Collidern (FLC)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF3-611) (POF3-611)
2. DFG project 13245592 - SFB 676: Teilchen, Strings und frühes Universum: Struktur von Materie und Raum-Zeit (13245592) (13245592)
3. PHGS, VH-GS-500 - PIER Helmholtz Graduate School (2015_IFV-VH-GS-500) (2015_IFV-VH-GS-500)

Experiment(s):

1. Facility (machine) ILC

Appears in the scientific report 2018

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Database coverage:

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