Fermionic third generation top partners are generic in composite Higgs models. They are likely to decay into third generation quarks and electroweak bosons. We propose a novel cut-and-count-style analysis in which we cross correlate the model-depende
nt single and model-independent pair production processes for the top partners $X_{5/3}$ and $B$. In the class of composite Higgs models we study, $X_{5/3}$ is very special as it is the lightest exotic fermion. A constraint on the mass of $X_{5/3}$ directly extends to constrains on all top partner masses. By combining jet substructure methods with conventional reconstruction techniques we show that in this kind of final state a smooth interpolation between the boosted and unboosted regime is possible. We find that a reinterpretation of existing searches can improve bounds on the parameter space of composite Higgs models. Further, at 8 TeV a combined search for $X_{5/3}$ and $B$ in the $l+rm{jets}$ final state can be more sensitive than a search involving same-sign dileptons.
We discuss novel effects in the phenomenology of a light Higgs boson within the context of composite models. We show that large modifications may arise in the decay of a composite Nambu-Goldstone boson Higgs to a photon and a Z boson, h -> Z gamma. T
hese can be generated by the exchange of massive composite states of a strong sector that breaks a left-right symmetry, which we show to be the sole symmetry structure responsible for governing the size of these new effects in the absence of Goldstone-breaking interactions. In this paper we consider corrections to the decay h -> Z gamma obtained either by integrating out vectors at tree level, or by integrating out vector-like fermions at loop level. In each case, the pertinent operators that are generated are parametrically enhanced relative to other interactions that arise at loop level in the Standard Model such as h -> gg and h -> gamma gamma. Thus we emphasize that the effects of interest here provide a unique possibility to probe the dynamics underlying electroweak symmetry breaking, and do not depend on any contrivance stemming from carefully chosen spectra. The effects we discuss naturally lead to concerns of compatibility with precision electroweak measurements, and we show with relevant computations that these corrections can be kept well under control in our general parameter space.
In this review, we discuss methods of parsing direct and indirect information from collider experiments regarding the Higgs boson and describe simple ways in which experimental likelihoods can be consistently reconstructed and interfaced with model p
redictions in pertinent parameter spaces. Ultimately these methods are used to constrain a five-dimensional parameter space describing a model-independent framework for electroweak symmetry breaking. We review prevalent scenarios for extending the electroweak symmetry breaking sector relative to the Standard Model and emphasize their predictions for nonstandard Higgs phenomenology that could be observed in LHC data if naturalness is realized in particular ways. Specifically we identify how measurements of Higgs couplings can be used to imply the existence of new physics at particular scales within various contexts, highlighting some parameter spaces of interest in order to give examples of how the data surrounding the new state can most effectively be used to constrain specific models of weak scale physics.
Recent excesses across different search modes of the collaborations at the LHC seem to indicate the presence of a Higgs-like scalar particle at 125 GeV. Using the current data sets, we review and update analyses addressing the extent to which this st
ate is compatible with the Standard Model, and provide two contextual answers for how it might instead fit into alternative scenarios with enlarged electroweak symmetry breaking sectors.
We discuss the role that Higgs coupling measurements can play in differentiating supersymmetric extensions of the Standard Model. Fitting current LHC data to the Higgs couplings, we find that the likelihood fit shows a preference in the direction of
suppressed (enhanced) bottom (top) quark couplings. In the minimal supersymmetric Standard Model, we demonstrate that for tan beta > 1, there is tension in achieving such fermion couplings due to the structure of the Higgs quartic couplings. In anticipation of interpreting supersymmetric models with future data, we determine a single straightforward condition required to access the region of coupling space preferred by current data.
We present up-to-date constraints on a generic Higgs parameter space. An accurate assessment of these exclusions must take into account statistical, and potentially signal, fluctuations in the data currently taken at the LHC. For this, we have constr
ucted a straightforward statistical method for making full use of the data that is publicly available. We show that, using the expected and observed exclusions which are quoted for each search channel, we can fully reconstruct likelihood profiles under very reasonable and simple assumptions. Even working with this somewhat limited information, we show that our method is sufficiently accurate to warrant its study and advocate its use over more naive prescriptions. Using this method, we can begin to narrow in on the remaining viable parameter space for a Higgs-like scalar state, and to ascertain the nature of any hints of new physics---Higgs or otherwise---appearing in the data.
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, prod
ucing large and potentially dangerous flavor changing neutral currents (FCNCs). 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 FCNCs mediated by a light enough Higgs (specially their contribution to $epsilon_K$) 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 $htomutau$ or $hto tc$, or the exotic top decay channel $tto c h$, are finally addressed.
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 (bul
k 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 tree-level flavor changing couplings will be strongly constrained by the experimental bounds on $Delta F=2$ 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.
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 flavor constraints, namely, epsilon_K and BR(b -> s gamma), 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 sim 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 epsilon_K in the two-site model to that in 5D models, including both the cases of a brane-localized and bulk Higgs.
