On the Flavor Problem in Strongly Coupled Theories - THEP Mainz

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174 Chapter 4. The Asymmetry in Top Pair Production C � V u u 10 5 0 �5 99� CL 95� CL 68� CL �10 �20 �10 0 10 20 Figure 4.10: The figure shows the CL ellipses described in 4.7 and a scatterplot of the parameter set in the � C V uū − � C A uū plane for the minimal model colored red and for the model with extended color gauge group for tan β = 1/2 and θ = 45 ◦ in green. C � A u u �
5 Conclusions Whenever the Large Hadron Collider begins a new run, the first sign of physics beyond the Standard Model could be revealed, and this becomes more likely with the recorded luminosity growing exponentially. However, as long as the mass gap between the Higgs and new physics resonances grows, theories which naturally predict new particles with masses around the electroweak scale become more and more tuned. In the Randall Sundrum model and its dual description by a strongly coupled theory, new resonances are only expected in the multiple TeV range, and, due to the RS GIM mechanism, couple more or less exclusively to top quarks. As was shown in Chapter 3 and 4, this can explain why they have stayed below the radar of the ever increasing exclusion limits of the LHC. In addition, the RS model arguably provides the best explanation of flavor we have today. Both the absence of FCNCs as well as the structure of the CKM matrix can be explained based on the fact that the quarks are localized differently along the extra dimension, which can be interpreted as a mixing with new composite degrees of freedom. As a result, flavor bounds are suppressed by orders of magnitude compared to general new physics without such a protection mechanism. This becomes apparent in the generically good agreement of the RS predictions for the flavor changing processes studied in Chapter 3. We find that both the contributions to Sψφ and ∆Γ/Γ in the Bs − ¯ BS system as well as the branching ratios B � Bs → µ + µ −� and B � Bd → µ + µ −� do not exceed the experimental expectations and can even lead to an improved agreement, even if the contributions from the custodially protected model are taken into account. It is thus remarkable that the RS-GIM mechanism leads to a broad agreement with measurements in the flavor sector, except for indirect CP violation in the Kaon system, which requires one percent fine-tuning despite the good suppression for the light flavors involved. It was extensively discussed how this problem arises and how it can be ameliorated following the approaches proposed in the literature. Most of these solutions modify the Yukawa couplings or constrain the localization parameters for the quarks, whose randomness is essential for the explanation of the flavor structure of the CKM matrix. A new solution has been motivated by the observation, that the dangerous contributions to ɛK arise almost exclusively because of the exchange of color-charged resonances, the KK modes of the gluon. The extension of the strong interaction gauge group to a SU(3)D ×SU(3)S surprisingly cancels these contributions independently of the imposed boundary conditions for the bulk fields and the choice of gauge couplings for the two subgroups. Invoking the AdS/CFT duality, in a detailed analysis the part of the 5D gauge boson propagator which is responsible for the excessive contributions could be related to the purely composite contribution of the mixed elementary-composite propagator in Chapter 2. This allowed for a deeper understanding of the cancellation, that protects ɛK and ultimatively leads to an RS model in agreement with all bounds from the quark flavor sector. In Chapter 3, the thorough implementation of this model is
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On the Flavor Problem in Strongly C
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UNIVERSITY OF MAINZ ABSTRACT THEORE
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Contents Acknowledgements vii Prefa
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Acknowledgements First and foremost
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x One of the most fascinating insig
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2 Chapter 1. Introduction: Problems
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10 Chapter 1. Introduction: Problem
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36 Chapter 2. The Randall Sundrum M
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92 Chapter 3. Solving the Flavor Pr
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100 Chapter 3. Solving the Flavor P
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Page 134 and 135: 124 Chapter 3. Solving the Flavor P
Page 156 and 157: 146 Chapter 4. The Asymmetry in Top
Page 186 and 187: 176 Chapter 5. Conclusions describe
Page 188 and 189: 178 Appendix A. Generating Paramete
Page 190 and 191: 180 Appendix A. Generating Paramete
Page 192 and 193: 182 Appendix B. Neutral Meson Mixin
Page 194 and 195: 184 Appendix B. Neutral Meson Mixin
Page 197 and 198: C Input Parameters This appendix is
Page 199: Parameter Value ± Error Reference
Page 202 and 203: 192 Appendix D. Higgs Potential for
Page 204 and 205: 194 Bibliography [13] S. Dimopoulos
Page 206 and 207: 196 Bibliography [43] G. Nordström
Page 208 and 209: 198 Bibliography [72] K. S. Babu,
Page 210 and 211: 200 Bibliography [104] R. Contino a
Page 212 and 213: 202 Bibliography [133] M. Baak, M.
Page 214 and 215: 204 Bibliography [160] J. Charles,
Page 216 and 217: 206 Bibliography [185] C. Csaki, G.
Page 218 and 219: 208 Bibliography [213] E. Thomson e
Page 220: 210 Bibliography [239] V. Ahrens, A
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On the Flavor Problem in Strongly Coupled Theories - THEP Mainz

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