In the context of a warped extra-dimension with Standard Model fields in the bulk, we obtain the general flavor structure of the Radion couplings to fermions and show that the result is independent on the particular nature of the Higgs mechanism (bulk or brane localized). These couplings will be generically misaligned with respect to the fermion mass matrix when the fermion bulk mass parameters are not all degenerate. When the Radion is light enough, the generic size of these treelevel flavor changing couplings will be strongly constrained by the experimental bounds on ∆F = 2 processes. At the LHC the possibility of a heavier Radion decaying into top and charm quarks is then considered as a promising signal to probe the flavor structure of both the Radion sector and the whole scenario. PACS numbers:Introducing a warped extra-dimension in such a way as to create an exponential scale hierarchy between the two boundaries of the extra dimension [1] has generated a lot of attention in the recent years as a novel approach to solve the hierarchy problem. By placing the Standard Model (SM) fermions in the bulk of the extra dimension it was then realized that one can simultaneously address the fermion mass hierarchy puzzle [2]. In this context the main constraints come from precision electroweak bounds as well as from low energy flavor violating processes [3,4,5,6], pushing the scale of new physics (the mass of the lowest KK excitations) to several TeV. In these scenarios, the metric fluctuations contain a scalar degree of freedom -the Radion, whose mass and couplings could make it the first new physics state to be discovered at the LHC. In the original RS1 setup [1], the Radion phenomenology was extensively studied and analyzed including the possibility of some amount of mixing with the Higgs scalar [7,8,9]. But it wasn't until relatively recently [10,11,12] that Radion interactions with bulk SM fields were fully considered. In this letter we want to extend these last investigations to include the full fermion flavor structure to the Radion couplings and show that as opposed to the original RS1 scenario, there is a prediction for generic flavor violating Radion couplings to fermions. The spacetime we consider takes the usual Randall-Sundrum form [1]:with the UV (IR) branes localized at z = R (z = R ′ ). The Radion can be parametrized by the following scalar perturbation of metric:Demanding that the perturbed metric solves the Einstein equation and that the Radion field is canonically normalized, we getwhere r(x) is the corresponding canonically normalized Radion graviscalar with its associated interaction scale Λ r = √ 6 R R ′ M P l . We assume that some unknown dynamics (e.g. the Goldberger-Wise mechanism [13]) will fix the inter-brane distance and give a positive mass squared to the Radion, and that it gives negligible back-reaction to the metric. The couplings between bulk SM fermions and the Radion are calculated in [11] in the case of one generation, with a brane localized Higgs. We are interested here in the flavor...

We study flavor violation in the quark sector in a purely 4D, two-site effective field theory description of the Standard Model 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, ǫ K and BR (b → sγ), 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 ∼ 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 ǫ K in the two-site model to that in 5D models, including both the cases of a brane-localized and bulk Higgs.

In the context of a warped extra-dimension with Standard Model fields in the bulk, we obtain the general flavor structure of the Higgs couplings to fermions. These couplings will be generically misaligned with respect to the fermion mass matrix, producing large and potentially dangerous flavor changing neutral currents (FCNC's). As recently pointed out in [arXiv:0906.1542], a similar effect is expected from the point of view of a composite Higgs sector, which corresponds to a 4D theory dual to the 5D setup by the AdS-CFT correspondence. We also point out that the effect is independent of the geographical nature of the Higgs (bulk or brane localized), and specifically that it does not go away as the Higgs is pushed towards the IR boundary. The FCNC's mediated by a light enough Higgs (specially their contribution to ǫK ) could become of comparable size as the ones coming from the exchange of Kaluza-Klein (KK) gluons. Moreover, both sources of flavor violation are complementary since they have inverse dependence on the 5D Yukawa couplings, such that we cannot decouple the flavor violation effects by increasing or decreasing these couplings. We also find that for KK scales of a few TeV, the Higgs couplings to third generation fermions could experience suppressions of up to 40% while the rest of diagonal couplings would suffer much milder corrections. Potential LHC signatures like the Higgs flavor violating decays h → µτ or h → tc, or the exotic top decay channel t → ch, are finally addressed.

We present an analysis of the loop-induced couplings of the Higgs boson to the massless gauge fields (gluons and photons) in the warped extra dimension models where all standard model fields propagate in the bulk. We show that in such models corrections to the hgg and h couplings are potentially very large. These corrections can lead to generically sizable deviations in the production and decay rates of the Higgs boson, even when the new physics states lie beyond the direct reach of the LHC. 1 One of the main differences between our work and previous analysis is that we present analytical results for the contribution of the full KK fermion tower. Other subtle differences are discussed in the main text.PHYSICAL REVIEW D 82, 056004 (2010) 1550-7998= 2010=82(5)=056004 (12) 056004-1

We examine the potential of using colliders to distinguish models with parity (Z 2 ) stabilized dark matter (DM) from models in which the DM is stabilized by other symmetries, taking the latter to be a Z 3 symmetry for illustration. The key observation is that a heavier mother particle charged under a Z 3 stabilization symmetry can decay into one or two DM particles along with Standard Model (SM) particles. This can be contrasted with the decay of a mother particle charged under a parity symmetry; typically, only one DM particle appears in the decay chain. The arXiv:1003.0899 studied the distributions of visible invariant mass from the decay of a single such mother particle in order to highlight the resulting distinctive signatures of Z 3 symmetry versus parity symmetry stabilized dark matter candidates. We now describe a complementary study which focuses on decay chains of the two mother particles which are necessarily present in these events.We also include in our analyss the missing energy/momentum in the event. For the Z 3 symmetry stabilized mothers, the resulting inclusive final state can have two, three or four DM particles. In contrast, models with Z 2 symmetry can have only two. We show that the shapes and edges of the distribution of M T 2 -type variables, along with ratio of the visible momentum/energy on the two sides of the event, are powerful in distinguishing these different scenarios. Finally we conclude by outlining future work which focus on reducing combinatoric ambiguities from reconstructing multi-jet events. Increasing the reconstruction efficiency can allow better reconstruction of events with two or three dark matter candidates in the final state.