천체입자물리 및 우주론 이론 연구실(최기영 교수님)에서 IBS 순수물리이론연구단의 신창섭 박사님을 초청하여 세미나를 개최합니다.

학과 구성원 여러분의 많은 참석을 부탁드립니다.

○ Time: 3:30 pm on June 11, 2018(Monday)

○ Place: Seminar Room of Basic Science Institute (31317 on the 3^rd floor)

○ Speaker: Dr. Chang Sub Shin (IBS 순수물리이론연구단)

○ Title: Spontaneous Leptogenesis in Continuum-Clockwork Axion Models

○ Abstract: The mechanism of “spontaneous leptogenesis” — in which the matter-antimatter asymmetry is generated via motion of a scalar field coupled to the electroweak gauge bosons — provides an interesting alternative to more traditional thermal leptogenesis models. While an axion-like field is a natural candidate for these models, the observed asymmetry requires an axion mass so large it decays shortly after leptogenesis. In this talk, we demonstrate how effective axion potentials that arise from continuum clockwork models can yield simultaneously sufficient production of baryon asymmetry, and a stable dark matter candidate with the appropriate abundance. Moreover, we find non-trivial dynamics early in the axion field evolution which exhibit a “tracking” behavior — similar to that found in quintessence models — where the axion follows a radiation-like equation of state before undergoing coherent oscillations. As a result of these dynamics, axion-photon isocurvature perturbations are generically suppressed, thereby enlarging the viable parameter space for our model.