Searching for beyond the minimal supersymmetric standard model at the laboratory and in the sky [Elektronische Ressource] / vorgelegt von Ju Min, Kim

Ju Min Kim

Sujets

• Physik

Informations

• Publié par: rheinische_friedrich-wilhelms-universitat_bonn
• Publié le: 01 janvier 2010
• Nombre de lectures: 11
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Searching for Beyond the
Minimal Supersymmetric Standard Model
at the Laboratory and in the Sky
Dissertation
zur
Erlangung des Doktorgrades (Dr. rer. nat.)
der
Mathematisch-Naturwissenschaftlichen Fakult¨at
der
Rheinischen Friedrich-Wilhelms-Universit¨at Bonn
vorgelegt von
Ju Min, Kim
aus
Seoul
Bonn Mai, 2010Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakult¨at der
Rheinischen Friedrich-Wilhelms-Universit¨at Bonn.
1. Gutachter: Prof. Dr. Manuel Drees
2. Gutachter: Priv. Doz. Dr. Stefan F¨orste
Tag der Promotion: 27.7.2010
Erscheinungsjahr: 2010
2Abstract
WestudythecollidersignalsaswellasDarkMattercandidatesinsupersymmetricmodels.
We show that the collider signatures from a supersymmetric Grand Unification model
basedontheSO(10)gaugegroupcanbedistinguishablefromthosefromthe(constrained)
minimalsupersymmetricStandardModel,eventhoughtheysharesomecommonfeatures.
The N = 2 supersymmetry has the charateristically distinct phenomenology, due to the
Dirac nature of gauginos, as well as the extra adjoint scalars. We compute the cold Dark
Matter relic density including a class of one-loop corrections. Finally, we discuss the
detectability of neutralino Dark Matter candidate of the SO(10) model by the direct and
indirect Dark Matter search experiments.
3First of all, I appreciate Manuel Drees for his patience during the whole period of my
Ph. D. He indeed deserves to be called my ’Doktorvater’. I thank my collaborators; in
particular,PeterZerwasandChoiSeongyoul,fromwhomIlearnedsomuchwhileworking
together. I thank former and present group members of Manuel; among others, Mitsuru
Kakizaki and Siba P. Das, for having never minded to answer my questions. I thank
Andreas Wisskirchen, without whose help on the computer I might have needed a few
more weeks until I finish. I thank Stefan F¨orste, Klaus Desch, and Uli Klein for being the
committee members.
I am grateful to Tae-Won Ha for helping me so much to keep the mental health. I
thank him also for having read this thesis carefully. Finally, very special thanks go to my
parents for having constantly supported me.
4Contents
1 Introduction 6
1.1 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2 Publication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Collider Signals from Supersymmetric Models 14
2.1 Current Accelerator Constraints . . . . . . . . . . . . . . . . . . . . . . . 14
2.1.1 Electroweak precision experiments . . . . . . . . . . . . . . . . . . 14
2.1.2 Constraints from direct searches . . . . . . . . . . . . . . . . . . . 15
2.2 Minimal Supergravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.1 Production and decays of the Supersymmetric particles . . . . . . 15
2.2.2 Signatures at the LHC: Benchmark points . . . . . . . . . . . . . . 22
2.3 Supergravity Grand Unified Theory . . . . . . . . . . . . . . . . . . . . . 27
2.3.1 General Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.3.2 A Detailed Study: An SO(10) Model . . . . . . . . . . . . . . . . . 28
2.4 N =2 Supersymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.4.1 Theoretical basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.4.2 QCD Sector: Color-Octet Scalar . . . . . . . . . . . . . . . . . . . 46
2.4.3 Electroweak Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3 Dark Matter 81
3.1 Dark Matter Relic Density . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.1.1 Standard Computation . . . . . . . . . . . . . . . . . . . . . . . . 81
3.1.2 One-loop Corrections. . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.2 Direct and Indirect Dark Matter Detection . . . . . . . . . . . . . . . . . 98
3.2.1 Theoretical Basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
3.2.2 An Example: Neutralino Dark Matter in an SO(10) Model . . . . 100
4 Summary and Conclusion 109
A Parametrizations of the thermal averages 111
B Comparison to a full one-loop calculation 112
51 Introduction
The Standard Model (SM) of particle physics, which is a renormalizable quantum field
theory based on the gauge symmetry, has been highly successful in a sense that its pre-
dictions agree very well with the experimental data of, M , the τ lifetime, and the muonW
anomalous magnetic moment, to name but a few [5].
Nevertheless, there are reasons to expect that the Standard Model is not the final
theory of Nature from the theoretical point of view: First, there is no room for gravity in
Standard Model [1]. Also, the choice of the gauge groups and the particle representations
areadhoc. Finally, theHiggssector, acrucialingredientfortheStandardModeltowork,
is not very well understood.
Let us discuss the final point a bit more in detail. The Higgs, introduced to break
the Electroweak symmetry through the nonvanishing vacuum expectation value, as the
Universe gets cooled down, is a fundamental scalar field, which receives quadratically
divergent radiative corrections in the Quantum Field Theory. Since we need Higgs not
heavier than a few hundred GeV for the perturbativity of the model, if we assume the
18Standard Model to be valid up to the Planck scale (M ∼ 10 GeV), we must cancelP
−30the bare and renormalized mass by fine tunning ofO(10 ). This, often called “Gauge
heirarchy problem”, can be solved, if some New Physics appears at TeV scale, for the
18cut-off scale in the radiative corrections now is a (few) TeV instead of 10 GeV.
Ontheotherhand,perhapsmoreimportantly,thereareexperimentalevidencesforthe
physics beyond the Standard Model: The neutrino oscialltion has been reported since the
first discovery by SuperKamiokande [6], which can be explained by nonvanishing (albeit
very tiny) neutrino masses. Also, the existence of non-baryonic cold Dark Matter (DM),
which does not exist in the SM, is by now well established [7].
Amongst various candidates for the New Physics, supersymmetry (SUSY) is partic-
ularly interesting. First of all, it is a natural generalization of space-time symmetries
of Quantum Field Theory. It has been shown that [8], under the basic assumptions of
Field Theory, the most general continuous symmetry of the S-matrix is a direct prod-
uct of the super-Poincar´e group (supersymmetry, tanslations, rotations, boosts) and the
internal symmetry group. Another important property is stability under the radiative
corrections. One can show that there are no perturbative loop corrections to the superpo-
tential, for instance, by using the fact that the superpotentials are holomorphic [9]. From
the practical point of view, the standard concepts of Quantum Field Theory are valid in
supersymmetry, together with its calculability, which is essential in doing physics.
The weakest point of supersymmetry is, however, that it must be broken to be the
theory describing our world, where we have not yet observed any of the supersymmetric
partners of the Standard Model particles. Even though there is not yet a model which
6convinced the community, the suggested models share a common feature of assuming
a “hidden sector” whose dynamics breaks supersymmetry. The SUSY breaking is then
transmitted to the observable sector by a messenger sector. Here we list two most studied
supersymmetry breaking mediation mechanisms:
• Gravity-mediated supersymmetry breaking The effect of SUSY breaking is mediated
by gravitational interactions. The models are based on the local supersymmetry,
where the parameters are space-time dependent. The SUSY algebra shows that
an invariance under local SUSY transformation implies an invariance under a local
coordinate shift. Hence, the local supersymmetry is called supergravity (SUGRA).
When SUSY is broken spontaneously in the hidden sector, the goldstino degrees of
freedomareabsorbedbythegravitinowhichobtainsamass,m . Theenergyscale3/2
intheSUSYbreakinginthehiddensectorcanbewrittenintermsofgravitinomass
and the Planck scale (albeit model dependent), and the SUSY breaking masses and
the couplings are generally set by m .3/2
• Gauge-mediated supersymmetry breaking The effect of SUSY breaking is mediated
by gauge interactions. SUSY is broken when a SM singlet superfield obtains the
vacuum expectation value, and the (s)particles in the observable sector “feel” the
SUSYbreakingviatheircouplingstothemessengerparticlesinloops. Thesparticle
massesare(loop-)suppressedbythemessengersectormassscale,whilethegravitino
mass, determined by the fundamental SUSY breaking, is suppressed by the Planck
scale. Therefore, in this scenario, the gravitino may be the lightest supersymmetric
particle (LSP).
Field SU(3) ,SU(2) ,U(1)C L Y? !
νeLL= (1, 2, -1 )
eL
¯E (1, 1, 2)? !
uL 1Q= (3, 2, )
3
dL
4¯ ¯U (3, 1, - )
3
2¯ ¯D (3, 1, )
3
¯H (1, 2, -1)d
H (1, 2, 1)u
Table 1: The matter and Higgs superfield content of the MSSM.
7Minimal Supersymmetric Standard Model
Now let us turn to the model realizing the idea of supersymmetry. The simplest in this
species is the Minimal Supersymmetric Standard Model (MSSM) [2, 3]. It is minimal, in
a sense that,
• The gauge group is SU(3) ×SU(2) ×U(1) .C L Y
• Only one fermionic generator (N = 1) for the supersymmetry transformation i