Topological Interactions in the Higgsless Model at the LHC

Topological quantum interactions, namely Chern-Simons terms and global Wess-Zumino terms, arise naturally in theories with extra dimensions of space compactified on orbifolds. If the extra dimensions become manifest at the TeV scale, experiments at the Large Hadron Collider (LHC) could observe signatures of topological interactions. Decays of Kaluza-Klein excitations of neutral electroweak gauge bosons into pairs of neutral Standard Model gauge bosons, ZZ and Z+photon, would provide a clean signature, since such decays do not occur at tree level. In this paper, we investigate the prospects for discovering such decays at the LHC, in the context of the Higgsless model of electroweak symmetry breaking. We identify the form of the relevant topological interactions, and estimate their strength. We find that in the minimal version of the model, the signal may be observed with about 100 inverse fb of data at the LHC using the Drell-Yan production process of the Kaluza-Klein gauge bosons. In addition, it is likely that the ultraviolet completion of the model would contain additional massive fermions, which can significantly enhance the signal. With two additional fermion multiplets, observation of the topological decay modes at the 3-sigma level would be possible with about 100 inverse fb of data using the highly model-independent vector boson fusion production channel.Comment: 18 pages, 8 figures. Discussion of Drell-Yan production process added in v3. This is the final version to appear in Physical Review