S. Aoki, T. Onogi, and S. Yokoyama. (2020)cite arxiv:2005.13233Comment: 5 pages, v2: minor corrections made to reduce possible confusions, references added.
L. Iorio. (2020)cite arxiv:2003.08244Comment: LaTex2e, 20 pages, 3 figures, no tables. Due to arXiv's space limitations, low-resolution pictures have been upoloaded. Some stylistic changes made.