Gauge-Higgs unification phenomenology in warped extra dimensions

My thesis will be based on a series of three papers [1,2,3], studying the properties of an extension of the Standard Model incorporating one warped extra dimension, with branes attached at two boundary points: ultraviolet brane and infrared brane, and a gauge structure enhanced compared to that of the Standard Model. The Higgs field may then be generated naturally from the fifth component of our gauge fields: Gauge-Higgs-Unification. Due to the gauge origin of the Higgs field, its potential is zero at tree-level. However, at one-loop, the Higgs field acquires an effective potential which leads naturally to the Higgs field acquiring a non-zero vacuum expectation value and therefore to electroweak symmetry breaking.;In Ref. 1, we computed this effective potential and demonstrated that electroweak symmetry breaking may be realized, with a Higgs mass in the range mh ∼ 120-170 GeV. Moreover, this leads to the proper generation of the top and bottom quark masses for the same region of bulk mass parameters that lead to good agreement with experimental data, including radiative corrections, in the presence of a light Higgs. In addition, we computed the masses of the first few excited modes of the top, and showed that the t1 was light enough to be produced by the decay of the first excited gluon, G1.;In Ref. 2, we computed the couplings of the zero modes and the first excited states of the gluons, the W's and the Z gauge bosons, as well as the Higgs, to the zero modes and first excited states of the third generation quarks. Using the parameter space consistent with experimental data and radiative electroweak symmetry breaking, we numerically studied the dependence of these couplings on the parameters of our model. Furthermore, as mentioned above, light excited states of the top quark exist which couple strongly to the Kaluza-Klein gauge bosons and which provide the main decay mode of the lightest Kaluza-Klein gluon state. Therefore, we studied the collider phenomenology at the LHC. In particular, we concentrated on the possible detection of the first excited state of the top, t 1, adding the contribution from the additional G 1 production channel, and showed that this tends to lead to a higher reach for thet1 mass than is accessible via regular QCD production processes.;Recently, in Ref. 3, we investigated the conditions necessary to obtain realistic charged lepton and neutrino masses and demonstrated that it was possible to generate these masses consistent with experimental observations. Dark-matter may also be realized by extending this model by a new sector which is odd under a parity symmetry, Z2, preserved in the bulk, thus establishing a relationship between the mass parameters that control neutrino masses and those that control dark-matter density. The lightest odd particle (LOP) is then our dark-matter candidate. A particular challenge in this work was understanding the effects of including Majorana mass terms on both the ultraviolet and the infrared branes for the odd sector. We were able to generate the observed dark-matter density for an LOP with mass ∼ O (1) TeV in the Dirac case. This mass could be lowered to approximately 0.5 TeV with the inclusion of Majorana mass terms. Additionally, the LOP couples strongly to the Higgs and therefore can have a significant scattering cross-section with nuclei via processes mediated by the exchange of the Higgs boson. We showed that the LOP consistent with the observed dark-matter constraints will be probed in the near future in experiments such as CDMS and Xenon.