2008/10/31 by Kaustubh Agashe, Aleksandr Azatov, Lijun Zhu · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Coupling (piping) #Gauge (firearms) #Observable #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Planck #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Quark #Standard Model (mathematical formulation) #Theoretical physics #Yukawa potential #hep-ph
paper · pdf · doi:10.1103/physrevd.79.056006
46 pages with 10 figures
arxiv created 2008/10/31 · openalex publication_date 2009/03/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study flavor violation in the quark sector in a purely 4D, two-site effective field theory description of the standard model (SM) and just their first Kaluza-Klein excitations from a warped extra dimension. The warped 5D framework can provide solutions to both the Planck-weak and flavor hierarchies of the SM. It is also related (via the AdS/CFT correspondence) to partial compositeness of the SM. We focus on the dominant contributions in the two-site model to two observables which we argue provide the strongest constraints from flavor violation, namely, ϵK and BR(b\ensuremath→s\ensuremathγ), where contributions in the two-site model occur at tree and loop-level, respectively. In particular, we demonstrate that a ``tension'' exists between these two observables in the sense that they have opposite dependence on composite site Yukawa couplings, making it difficult to decouple flavor-violating effects using this parameter. We choose the size of the composite site QCD coupling based on the relation of the two-site model to the 5D model (addressing the Planck-weak hierarchy), where we match the 5D QCD coupling to the 4D coupling at the loop-level and assuming negligible tree-level brane-localized kinetic terms. We estimate that a larger size of the 5D gauge coupling is constrained by the requirement of 5D perturbativity. We find that \ensuremath∼O(5) TeV mass scale for the new particles in the two-site model can then be consistent with both observables. We also compare our analysis of ϵK in the two-site model to that in 5D models, including both the cases of a brane-localized and bulk Higgs.