All possible lightest supersymmetric particles in proton hexality violating minimal supergravity models and their signals at hadron colliders [Elektronische Ressource] / vorgelegt von Sebastian Grab

Sebastian Grab

Sujets

• Physik

Informations

• Publié par: rheinische_friedrich-wilhelms-universitat_bonn
• Publié le: 01 janvier 2009
• Nombre de lectures: 28
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

All Possible Lightest Supersymmetric Particles
in Proton Hexality Violating
Minimal Supergravity Models and
their Signals at Hadron Colliders
Dissertation
zur
Erlangung des Doktorgrades (Dr. rer. nat.)
der
Mathematisch-Naturwissenschaftlichen Fakult¨at
der
Rheinischen Friedrich-Wilhelms-Universit¨at
zu Bonn
vorgelegt von
Sebastian Grab
geb. in
Altenkirchen
Bonn 2009ii
AngefertigtmitGenehmigungderMathematisch-NaturwissenschaftlichenFakult¨at
der Universit¨at Bonn.
Referent: Prof. Herbert Dreiner
Korreferent: Prof. Manuel Drees
Tag der Promotion: 02.Juli 2009
Diese Dissertation ist auf dem Hochschulschriftenserver der ULB Bonn
http://hss.ulb.uni-bonn.de/diss online elektronisch publiziert.
Erscheinungsjahr: 2009
iiTo Christine
iiiAcknowledgements
I would like to thank several people and institutions. Without their experience and sup-
port, this thesis would not have been possible.
First of all, I would like to thank my supervisor Herbi Dreiner for his excellent support.
It has been a pleasure to work with him and to benefit from his expertise.
I would like to thank the Bonn-Cologne Graduate School of Physics and Astronomy and
especially the Deutsche Telekom Stiftung for financial support. Without their assistance
many fruitful visits to summer schools, workshops, conferences etc. would not have been
possible.
I also would like to express my gratitude to my collaboratorsBen Allanach, Markus Bern-
hardt, Siba Prasad Das, Klaus Desch, Sebastian Fleischmann, Steve Kom, Daniel Koschade,
Michael Kr¨amer, Ulrich Langenfeld, Ben O’Leary, Peter Richardson, and Maike Trenkel. I
hope that we will continue our good collaboration in the future.
I would also like to mention my working group who made working, studying and party-
ing a lot of fun. Thank you Alessandro Barri, Markus Bernhardt, Marja Hanussek, Jong
Soo “Zong” Kim, Olaf Kittel, Ulrich Langenfeld, Christoph Luhn, Anja Marold, Branislav
Poletanovic, Marc Thormeier and Karina Williams. I especially enjoyed many profound
discussions with Zong.
In addition, I benefited a lot from discussions with various other people including Sascha
Bornhauser,VolkerBu¨scher,ManuelDrees,GudrunHillert,SushitaKulkarni,NicolasMoeser,
Tilman Plehn, Jan Schumacher, and the TASI08 people. I also would like to thank the the-
ory groups of Fermilab NationalAccelerator, ArgonneNational Laboratory,UC Santa Cruz,
IPPP Durham, University of Karlsruhe, and Cambridge University for helpful discussions
and warm hospitality.
I am grateful to our secretaries, Dagmar Fassbender, Patricia Zu¨ndorf, and Sandra Heid-
brink, who helped me to survive at our institute.
I also would like to thank Ina Eisenschneider, Jong Soo Kim, Olaf Kittel, and Karina
Williams for reading parts of my thesis.
After my PhD, I will start to work in the excellent theory group of UC Santa Cruz.
I am therefore deeply grateful to my referees Herbi Dreiner, Michael Kr¨amer, and Peter
Richardson, who wrote letters of recommendation for my postdoc application.
Finally none of this would have been possible without the support of my family and my
lovely girlfriend Christine. Thank you!
ivAbstract
The most widely studied supersymmetric scenario is the minimal supersymmetric standard
model(MSSM)withmorethanahundredfreeparameters. Howeverfordetailedphenomeno-
logicalstudies, theminimal supergravity (mSUGRA)model, a restricted andwell-motivated
framework for the MSSM, is more convenient. In this model, lepton- and baryon-number
violating interactions are suppressed by a discrete symmetry, R-parity or proton-hexality,
to keep the proton stable. However, it is sufficient to forbid only lepton- or baryon-number
violation. We thus extend mSUGRA models by adding a proton-hexality violating operator
at the grand unification scale.
This can change the supersymmetric spectrum leading on the one hand to a sneutrino,
smuon or squark as the lightest supersymmetric particle (LSP). On the other hand, a wide
parameterregionisreopened, wherethescalartau(stau)istheLSP.Weinvestigate indetail
theconditionsleadingtonon-neutralinoLSPscenarios. Wetakeintoaccounttherestrictions
from neutrino masses, the muon anomalous magnetic moment, b→ sγ, and other precision
measurements. We furthermore investigate existing restrictions from direct searches at LEP,
the Tevatron, and the CERN pp¯collider.
It is vital to know the nature of the LSP, since supersymmetric particles normally cascade
decay down to the LSP at collider experiments. We present typical LHC signatures for
sneutrino LSP scenarios. Promising signatures are high-p muons and jets, like-sign muonT
events and detached vertices from long lived taus. We also classify the stau LSP decays
and describe their dependence on the mSUGRA parameters. We then exploit our results for
resonant single slepton production atthe LHC. We find novel signatures with like-sign muon
and three- and four-muon final states. Finally, we perform a detailed analysis for single
slepton production in association with a single top quark. We show that the signal can be
distinguished from the background at the LHC.
vContents
1. Introduction 1
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Goals of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3. Organization of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4. Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The Model 4
2.1. Global Supersymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. The Supersymmetric Standard Model . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Superpotential and Discrete Symmetries . . . . . . . . . . . . . . . . . . . . 8
2.4. mSUGRA with and without Proton Hexality P . . . . . . . . . . . . . . . . 106
2.4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4.2. Mass Spectrum of P mSUGRA Models . . . . . . . . . . . . . . . . . 126
2.4.3. The P violating mSUGRA model . . . . . . . . . . . . . . . . . . . . 166
3. All Possible LSP Candidates in P Violating mSUGRA Models 196
03.1. Non-χ˜ LSP Parameter Space . . . . . . . . . . . . . . . . . . . . . . . . . . 201
03.2. Non-χ˜ LSPs via LLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
03.3. Non-χ˜ LSPs via UDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
3.4. Conclusion of Section 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4. Sneutrino LSPs in B mSUGRA Models and Signals at the LHC 263
4.1. Experimental Bounds on Sneutrino LSP Models . . . . . . . . . . . . . . . . 26
4.1.1. Bounds from Tree Level Neutrino Masses . . . . . . . . . . . . . . . . 26
′4.1.2. Indirect Bounds on λ . . . . . . . . . . . . . . . . . . . . . . . . . . 27ijk
4.1.3. Collider Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1.3.1. Constraints from LEP . . . . . . . . . . . . . . . . . . . . . 29
4.1.3.2. Constraints from the Tevatron . . . . . . . . . . . . . . . . 30
4.1.3.3. Constraints from the CERN pp¯Collider . . . . . . . . . . . 32
4.2. Sneutrino LSP Parameter Space . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2.1. A Dependence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
4.2.2. A –tanβ Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
4.2.3. M –M Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391/2 0
′ ′ ′4.2.4. Sneutrino LSPs with λ | =λ or λ . . . . . . . . . . . . . . 42GUTijk 231 331
4.3. Hadron Collider Phenomenology . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.3.1. Example Spectrum and Branching Ratios. . . . . . . . . . . . . . . . 43
4.3.2. Sparticle Pair Production . . . . . . . . . . . . . . . . . . . . . . . . 46
4.3.3. Single Sparticle Production . . . . . . . . . . . . . . . . . . . . . . . 50
vi
6Contents vii
4.4. Conclusion of Section 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5. τ˜ LSP Phenomenology 531
5.1. New Phenomenology and Outline . . . . . . . . . . . . . . . . . . . . . . . . 53
′5.2. Renormalization Group Running of λ and λ . . . . . . . . . . . . . . . . 55i33ijk
5.2.1. Renormalization Group Equations . . . . . . . . . . . . . . . . . . . . 55
5.2.2. Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.2.3. Comparison with the Program SOFTSUSY . . . . . . . . . . . . . . . . 60
5.3. τ˜ LSP Decays in B mSUGRA . . . . . . . . . . . . . . . . . . . . . . . . . 611 3
5.3.1. General LSP Decay Modes . . . . . . . . . . . . . . . . . . . . . . . . 61
5.3.2. Dependence of τ˜ Decays on mSUGRA Parameters . . . . . . . . . . 631
5.4. Resonant Single Slepton Production in τ˜ LSP Scenarios . . . . . . . . . . . 681
5.4.1. General Signatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
′ ′5.4.2. λ | = 0, λ ≪λ . . . . . . . . . . . . . . . . . . . . . . . . 70GUT 2332jk 2jk
′5.4.3. λ | = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73GUT3jk
5.5. Single Smuon Production: An Explicit Numerical Example . . . . . . . . . . 74
5.5.1. Like-Sign Dimuon Events. . . . . . . . . . . . . . . . . . . . . . . . . 74
5.5.2. Discussion of Background and Cuts for Like-Sign Dimuon