Impacts of Radial Mixing on the Galactic Thick and Thin Disks

Using N-body simulations of the Galactic disks, we qualitatively study how the metallicity distributions of the thick and thin disk stars are modified by radial mixing induced by the bar and spiral arms. We show that radial mixing drives a positive vertical metallicity gradient in the mono-age disk population whose initial scale-height is constant and initial radial metallicity gradient is tight and negative. On the other hand, if the initial disk is flaring, with scale-height increasing with galactocentric radius, radial mixing leads to a negative vertical metallicity gradient, which is consistent with the current observed trend. We also discuss impacts of radial mixing on the metallicity distribution of the thick disk stars. By matching the metallicity distribution of N-body models to the SDSS/APOGEE data, we argue that the progenitor of the Milky Way's thick disk should not have a steep negative metallicity gradient.Comment: 4 pages, 1 figure, to appear in the proceedings of the IAU Symposium 334 "Rediscovering our Galaxy", Potsdam, 10-14 July 2017, eds. C. Chiappini, I. Minchev, E. Starkenburg, M. Valentin

Two-sided random walks conditioned to have no intersections

Let $S^{1},S^{2}$ be independent simple random walks in $\mathbb{Z}^{d}$ ($d=2,3$) started at the origin. We construct two-sided random walk paths conditioned that $S^{1}[0,\infty) \cap S^{2}[1, \infty) = \emptyset$.Comment: 25 page

Hadronic few-body systems in chiral dynamics, -- Few-body systems in hadron physics --

Hadronic composite states are introduced as few-body systems in hadron physics. The $\Lambda(1405)$ resonance is a good example of the hadronic few-body systems. It has turned out that $\Lambda(1405)$ can be described by hadronic dynamics in a modern technology which incorporates coupled channel unitarity framework and chiral dynamics. The idea of the hadronic $\bar KN$ composite state of $\Lambda(1405)$ is extended to kaonic few-body states. It is concluded that, due to the fact that $K$ and $N$ have similar interaction nature in s-wave $\bar K$ couplings, there are few-body quasibound states with kaons systematically just below the break-up thresholds, like $\bar KNN$, $\bar KKN$ and $\bar KKK$, as well as $\Lambda(1405)$ as a $\bar KN$ quasibound state and $f_{0}(980)$ and $a_{0}(980)$ as $\bar KK$.Comment: 8 pages, 2 figures, contribution to 20th International IUPAP Conference on Few-Body Problems in Physics (FB20), 20-25 August 2011, Fukuoka, Japa