Speaker
Description
We study an effective extension of the Standard Model that includes a U(1)' gauge symmetry and a pseudoscalar field. The model predicts a dark vector boson as a dark matter candidate and a heavier pseudoscalar that can behave as a long-lived particle at collider scales. The dark sector couples to the Standard Model through a dimension-5 operator, allowing the decay of the pseudoscalar into a dark photon and a visible photon, and through a Higgs portal interaction enabling Higgs decays into pseudoscalars.
In this poster, we focus on the collider phenomenology of the long-lived pseudoscalar. We simulate the model using MadGraph5_aMC@NLO, perform detector-level analysis with Delphes, and apply event selections targeting displaced photon signatures. As a final result, we present contour plots in the plane of the pseudoscalar mass and the dark sector coupling g_D, with the z-axis showing either the maximal branching ratio of the Higgs decay into pseudoscalars or the effective coupling strength required to produce visible signals. This work is part of an international collaboration between the Pontificia Universidad Católica del Perú (PUCP), Universidad San Sebastián (Chile), and Universidad de la República (Uruguay).
