Affiliation: | (1) Fixed Income Trading Department, Fixed Income Group, Mizuho Securities Co., Ltd., 1-5-1, Otemach, Chiyoda-ku, Tokyo 100-0004, Japan;(2) Department of Mathematical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan |