Electroweak precision observables as well as more recent LHC measurements push Composite Higgs model into unnatural region, with the vacuum misalignment angle $\sin\theta=v/f\lesssim 0.2$. Such values are difficult to achieve from the typical interactions that determine the vacuum alignment. I will show how the techni-sigma scalar excitation might alleviate this problem in a theory of Composite Higgs with a partially composite top quark. I will use unitarity arguments to estimate mass and couplings of this scalar state and discuss the possibility to observe it at the LHC. The work is based on arXiv:1809.09146.
报告人简介：Dr Diogo Buarque Franzosi has been working in the last years with dynamical electroweak symmetry breaking, Composite Higgs and new strong dynamics, aiming to address some of the problems of the Standard Model. In that quest he has mainly focused on the collider phenomenological aspects of these theories, trying to achieve higher accuracy and precision in the predictions of collider observables via the development of Monte Carlo generator tools, QCD corrections for effective field theories and the understanding of new signatures. After he got his PhD degree in Turin, he spent time in Louvain-la-Neuve, Odense, Goettingen and now in Gothenburg as posdoc and research assistant.