Speaker
Description
We investigate the role of the Higgs field as a fundamental scalar in the Standard Model within the framework of modular inflation models, where a modulus field acts
as the inflaton and its interactions are governed by an underlying modular symmetry. In
general, the Higgs field can participate in the dynamics of modular inflation, leading to a
two-field inflationary system—termed Higgs-Modular inflation—which exhibits non-trivial
dynamics and interesting phenomenological implications. We analyze Higgs-Modular inflation both analytically and numerically, highlighting its attractor behavior and the resulting
observational constraints. In particular, we find that Higgs-Modular inflation is favored by
the latest data release from the Atacama Cosmology Telescope (ACT) in certain regions
of parameter space. This is in contrast to both pure Higgs inflation and pure modular
inflation with a Starobinsky-type potential, which tend to predict a relatively low spectral
index. Additionally, we discuss the cutoff scale of this inflationary model and the reheating
processes induced by the decays of the modulus and the Higgs field.
