APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Wen Yin (Tohoku U)
Title: Light dark sector, quantum Zeno effect, and fuzzy Higgs boson
Date (JST): Wed, May 25, 2022, 14:00 - 15:00
Place: Zoom
Related File: 2808.pdf
Abstract: If the cosmologically well-motivated axion or dark gauge boson dark matter is relevant to a dark Higgs boson field, the SM-like Higgs boson invisible decay is induced via the Higgs portal coupling. In this talk, I discuss a quantum effect that is important if the Higgs field mixes with another singlet scalar field whose decay rate is larger than the mass difference between the two mass eigenstates. The resulting Higgs particle is not the eigenstate of the mass matrix, but it is approximately the eigenstate of the interaction. As a consequence, the mixing interaction decouples with a sufficiently large decay width of the exotic scalar even if the naive mixing parameter is not small. I will qualitatively understand this phenomenon by using the so-called quantum Zeno effect in quantum mechanics and show it quantitatively by using the QFT. Future Higgs factories may probe this scenario by precisely measuring the Higgs boson invisible decay rate and the deviation of the Higgs coupling.