Warped/composite phenomenology simplified

Abstract

This is the first of two papers aimed at economically capturing the collider phenomenology of warped extra dimensions with bulk Standard Model fields, where the hierarchy problem is solved non-supersymmetrically. This scenario is related via the AdS/CFT correspondence to that of partial compositeness of the Standard Model. We present a purely four-dimensional, two-sector effective field theory describing the Standard Model fields and just their first Kaluza-Klein/composite excitations. This truncation, while losing some of the explanatory power and precision of the full higherdimensional warped theory, greatly simplifies phenomenological considerations and computations. We describe the philosophy and explicit construction of our two-sector model, and also derive formulas for residual Higgs fine tuning and electroweak and flavor precision variables to help identify the most motivated parts of the parameter space. We highlight several of the most promising channels for LHC exploration. The present paper focusses on the most minimal scenario, while the companion paper addresses the even richer phenomenology of the minimal scenario of precision gauge coupling unification. *

Naturalness from a composite top?

“…If the heavy resonances are very wide, they are similar to the σ particle in QCD, and it could be highly non-trivial to find these particles at a hadron collider. 9 We also expect excited states of the new composite top quark, i.e. T .…”

“…See [9] for related discussions of fine-tuning in this context. This will modify the calculation of the Higgs (mass) 2 .…”

“…If ρ is lighter than the excited top state, T should dominantly decay to ρ + t and consequently lead to 3t or t + 2b in its final states. 9 One may also be worried that ρ may be lighter than ΛC if its coupling is smaller than 4π when N is sizable. However, we note that M ρ does not scale with N .…”

Single production of an exotic bottom partner at LHC

“…The choice of the representations of the composite fermions under this group defines different alternatives for the top partners. Second, the paradigm of partial compositeness: the masses of the SM fermions arise from mixing with composite fermions, that in turn couple with the Higgs [19,20]. Partial compositeness gives an economical mechanism to naturally obtain the hierarchy in the fermionic spectrum of the SM (although flavor mixing require some extra ingredients), it also gives rise to a mild separation of scales in the composite sector.…”

“…We will focus on the spectrum of bottom partners and their couplings to the SM fields relevant for single creation of resonances at LHC. For more details on this kind of effective theories we refer the reader to the original reference and to [20].…”