We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a $U(3)_\chi$ associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter $\chi$ which transforms as triplet under $U(3)_\chi$, and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator $\phi$ with a coupling $\lambda$. We identify a number of "flavor-safe" scenarios for the structure of $\lambda$ which are beyond Minimal Flavor Violation. For dark matter and collider phenomenology we focus on the well-motivated case of $b$-flavored dark matter. The combined flavor and dark matter constraints on the parameter space of $\lambda$ turn out to be interesting intersections of the individual ones. LHC constraints on simplified models of squarks and sbottoms can be adapted to our case, and monojet searches can be relevant if the spectrum is compressed.Comment: 40 pages, 19 figures, 3 tables. Clarifying comments and some references added, matches published versio
We present the electroweak and flavour structure of a model with a warped extra dimension and the bulk gauge group SU (3) c × SU (2) L × SU (2) R × P LR × U (1) X . The presence of SU (2) R implies an unbroken custodial symmetry in the Higgs system allowing to eliminate large contributions to the T parameter, whereas the P LR symmetry and the enlarged fermion representations provide a custodial symmetry for flavour diagonal and flavour changing couplings of the SM Z boson to left-handed down-type quarks. We diagonalise analytically the mass matrices of charged and neutral gauge bosons including the first KK modes. We present the mass matrices for quarks including heavy KK modes and discuss the neutral and charged currents involving light and heavy fields. We give the corresponding complete set of Feynman rules in the unitary gauge.
The impact of right-handed currents in both charged-and neutral-current flavour-violating processes is analysed by means of an effective theory approach. More explicitly, we analyse the structure of dimension-six operators assuming a left-right symmetric flavour group, commuting with an underlying SU (2) L ×SU (2) R ×U (1) B−L global symmetry, broken only by two Yukawa couplings. The model contains a new unitary matrix controlling flavour-mixing in the right-handed sector. We determine the structure of this matrix by charged-current data, where the tension between inclusive and exclusive determinations of |V ub | can be solved. Having determined the size and the flavour structure of right-handed currents, we investigate how they would manifest themselves in neutral current processes, including particle-antiparticle mixing, Z → bb, B s,d → µ + µ − , B → {X s , K, K * }νν, and K → πνν decays. The possibility to explain a non-standard CP-violating phase in B s mixing in this context, and the comparison with other predictive new-physics frameworks addressing the same problem, is also discussed. While a large S ψφ asymmetry can easily be accommodated, we point out a tension in this framework between |V ub | and S ψK .
We present a complete study of ∆S = 2 and ∆B = 2 processes in the leftright model (LRM) based on the weak gauge group SU (2) L × SU (2) R × U (1) B−L . This includes ε K , ∆M K , ∆M q , A q SL , ∆Γ q with q = d, s and the mixing induced CP asymmetries S ψK S and S ψφ . Compared to the Standard Model (SM) these observables are affected by tree level contributions from heavy neutral Higgs particles (H 0 ) as well as new box diagrams with W R gauge boson and charged Higgs (H ± ) exchanges. We also analyse the B → X s,d γ decays that receive important new contributions from the W L − W R mixing and H ± exchanges. Compared to the existing literature the novel feature of our analysis is the search for correlations between various observables that could help us to distinguish this model from other extensions of the SM and to obtain an insight into the structure of the mixing matrix V R that governs right-handed currents. Moreover, we perform the full phenomenology including both gauge boson and Higgs boson contributions. We find that even for M H 0 ≈ M H ± ∼ O(20) TeV, the tree level H 0 contributions to ∆F = 2 observables are by far dominant and the H ± contributions to B → X q γ can be very important, even dominant for certain parameters of the model. While in a large fraction of the parameter space this model has to struggle with the experimental constraint from ε K , we demonstrate that there exist regions in parameter space which satisfy all existing ∆F = 2, B → X s,d γ, tree level decays and electroweak precision constraints for scales M W R 2 − 3 TeV in the reach of the LHC. We also show that the S ψK S -ε K tension present in the SM can be removed in the LRM. Simultaneously Br(B → X s γ) can be brought closer to the data. However, we point out that with the increased lower bound on M W R , the LRM cannot help in explaining the difference between the inclusive and exclusive determinations of |V ub |, when all constraints are taken into account, unless allowing for large fine-tuning. Finally we present a rather complete list of Feynman rules involving quarks, gauge bosons and Higgs particles.
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