Долгоживущие суперпартнеры в минимальной суперсимметричной стандартной модели

• Автор: Мануэль Херардо Паукар Акоста
• Шифр специальности: 01.04.02
• Научная степень: Кандидатская
• Год защиты: 2010
• Место защиты: Дубна
• Количество страниц: 106 с. : ил.

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JOINT INSTITUTE FOR NUCLEAR RESEARCH BOGOLIUBOV LABORATORY OF THEORETICAL PHYSICS
Manuel Gerardo PAUCAR ACOSTA
Long-lived Superpartners in the Minimal Super symmetric Standard Model
Speciality. 01.04.02—Theoretical Physics
Thesis for the candidate degree in physical and mathematical sciences.
Scientific Supervisors:
Doctor of physical and mathematical sciences D.I. Kazakov
Candidate of physical and mathematical sciences A.V Gladyshev
Dubna 2010
Abstract
The discovery of Supersymmetry is one of the main goals in the proposed experiments at the Large hadron collider (LHC). However, search for supersymmetric particles at colliders usually proceeds from the assumption that all of them are relatively heavy (few hundreds of GeV) and shortlived. In this thesis, we performed a study on the probable existence of long-lived charged superpartners in some regions of parameter space in the framework of the MSSM with supergravity-inspired soft SUSY breaking. Three regions of interest are the co-annihilation region with light scalar charged taus, the region with large negative trilinear scalar coupling Aq distinguished by light scalar top quarks and the focus point region with light higgsino-like charginos where the Higgs parameters /i is small (less than Mz). The phenomenology of long-lived superpartners at the LHC is discussed.

Contents
1 Introduction
2 Supersymmetry and the Supersymmetric Extension of the Standard
Model
2.1 Supcrsymmetry
2.2 MSSM
2.2.1 Structure of the MSSM
2.3 Minimal Supergravity
2.4 The mSUGRA Sparticle Spectrum
2.4.1 Squarks and Sleptons
2.4.2 Neutralinos and Charginos
2.4.3 A Sample of mSUGRA Sparticle Spectrum
3 Favoured Regions of mSUGRA Parameter Space
3.1 Theoretical and Experimental Constraints
3.2 (mo-mi/2) Plane of Parameters Space
3.2.1 Favoured Parameter Regions
3.2.2 The case for Non-zero Ao
4 mSUGRA Co-annihilation Region and Long-lived Charged Sleptons
4.1 The (x?-r) Co-annihilation Region -motivations for Long-lived Sparticles
4.2 Long-lived r Charged Sparticle
4.3 Production Cross Section of Long-lived r Charged Sparticle at LHC
4.4 Discussion

parameter space. Other experimental constraints, for example, those coming from precision measurements: 6 —> S7 [100, 101, 102] is also taken into account.
3.2 (mo-mi/2) Plane of Parameters Space
The goal of this section is to delineate the regions of mSUGRA parameter space consistent with the theoretical and experimental constraints discussed in the previous section. For this purpose, we proceed to analyze the mSUGRA parameter space with the help of SUSY Spectrum codes by taking a vanishing/non-vanishing trilinear scalar coupling Aq, and/or by looking at fixed values of tan/3 while varying (mo,mp2). In this analysis all the mentioned constraints are used. We present our results below.
3.2.1 Favoured Parameter Regions
In our analysis, we have generated the My Sparticle spectrum from the input parameters at the Mqut by using the Fortran code SuSpect [103]
1. This code employs the two-loop RGEs and implements the REWSB mechanism. We have used the code MicrOmegas [104, 105] for computing the neutralino relic density. We have included LEP2 and Tevatron lower limits for superpartner masses and set top quark mass, mt — 172.7 GeV. We have also performed a detailed analysis of the mSUGRA parameters with another code as ISASUGRA/ISAJET [106] 2.
1We have set the following input values at Mw QtTm = 127.934, as = 0.1172, mi°le = 172.7 GeV, = 4.25 GeV, m?T°lc = 1.777 GeV.
2We have cross-checked our analysis using these codes and find no significant disagreement in most regions of parameter space. The largest sensitivity appears to arise for the case of large tan /3. A detailed analysis of such sensitivities and their implications for the analysis of relic density calculations can be