Domain-Wall Standard Model in non-compact 5D and LHC phenomenology

We propose a framework to construct “Domain-Wall Standard Model” in a non-compact 5-dimensional spacetime, where all the Standard Model (SM) fields are localized in certain domains of the 5th dimension and the SM is realized as a 4-dimensional effective theory without any compactification for the 5th dimension. In this context, we investigate the collider phenomenology of the Kaluza–Klein (KK) modes of the SM gauge bosons and the current constraints from the search for a new gauge boson resonance at the Large Hadron Collider Run-2. The couplings of the SM fermions with the KK-mode gauge bosons depend on the configuration of the SM fermions in the 5-dimensional bulk. This “geometry” of the model can be tested at the future Large Hadron Collider experiment, once a KK-mode of the SM gauge boson is discovered.

CONVOLUTION FORMULA AND FINITE W BOSON WIDTH EFFECTS IN TOP QUARK WIDTH

In the Standard Model, the top quark decay width Γt is computed from the exclusive t → bW decay. We argue in favor of using the three body decays [Formula: see text] to compute Γt as a sum over these exclusive modes. As dictated by the S-matrix theory, these three body decays of the top quark involve only asymptotic states and incorporate the width of the W boson resonance in a natural way. The convolution formula commonly used to include the finite width effects is found to be valid, in the general case, when the intermediate resonance couples to a conserved current (limit of massless fermions in the case of W bosons). The relation Γt = Γ(t → bW) is recovered by taking the limit of massless fermions followed by the W boson narrow width approximation. Although both calculations of Γt are different at the formal level, their results would differ only by tiny effects induced by light fermion masses and higher-order radiative corrections.