| 14 | 14 | The particle spectra of 2UED includes all of the Standard Model particles as well as their Kaluza-Klein excitations in either one or both of the compactified extra dimensions. Upon compactification one recovers the four dimensional gauge fields, but are left with 2 extra components. One of these components, the spinless adjoint to the gauge field, is invariant under 6D gauge transformations. The other, orthogonal excitation, shifts under such a transformation and corresponds to the Nambu-Goldstone boson eaten by the massive vector gauge field level by level. The 6D fermions have four components corresponding to the + or - 6D chiralities and the familiar L and R 4D chiralities. In order to insure 6D anomaly cancellation and fermion mass generation, the chiralities of the weak-doublet quarks (leptons) are forced to be opposite those of the weak-singlet quarks (leptons). That is, for each generation of quarks, there are the following fields: Q+ = (U+,D+), U-, D-, as well as the analogous fields for the leptons, including a - chirality neutrino field. Each of these 6D chiralities is composed of a combination of L and R handed components. Below is a table summarizing the 2UED particle content for the (0,0), (1,0) and (1,1) levels of excitation, where (0,0) are the standard model fields, (1,0) are fields with excitations in 1 extra dimension and (1,1) are fields with excitations in both extra dimensions. |
