Time: 10:00-12:00, 2023/12/13

Location: N018, Teaching building

Speaker: Shuta Ishigaki (Shanghai University)

Abstract:

The splitting and shifting of the spectra induced by applying a constant electric field is known as the Stark effect. It is similar to the Zeeman effect for applying a magnetic field. Unlike the magnetic field, however, a strong electric field causes dielectric breakdown with dissociation of the bound states. In QED, the corresponding phenomenon is known as the Schwinger effect. In 2308.00361, we explored these effects for the spectra induced by the electric field by using the top-down holographic model known as the D3/D7 model. The dual field theory is the N=4 SYM theory with N=2 fundamental hypermultiplets. The D7-brane provides the degrees of freedom for the quark-like sector. Taking the probe limit, we analyzed the behavior of the meson-like spectra for the entire range of the electric field. In a weak electric field, we observed both of the first and the second order Stark effects in the corresponding spectra. In a sufficiently strong electric field, the dielectric breakdown occurs, and the meson spectra are obtained as the frequencies of the quasinormal modes in the gravity side. Near the dielectric breakdown, we also observed that there are a lot of avoided crossings appearing. The residue of the Green's function has characteristic behavior at the center of each avoided crossing. We expect these behaviors of the bound states play a significant role for the dielectric breakdown in this system. In this talk, I present the results and details of our study.