Each year, to recognize significant achievements toward progress in physics, the Physical Society of Japan (JPS) selects outstanding papers from among original research articles published in the Journal of the Physical Society of Japan, Progress of Theoretical Physics, Progress of Theoretical and Experimental Physics, and JPS Conference Proceedings.
The selection committee has chosen the following five papers for the 2021 award based on 19 nominations (16 papers) from editors of the two journals and representatives of the 19 divisions of the JPS.
|Title of Article||Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment|
|Journal||Prog. Theor. Exp. Phys. 2019, 021D02 (2019)|
|Authors||H Ekawa, K Agari, J K Ahn, T Akaishi, Y Akazawa, S Ashikaga, B Bassalleck, S Bleser, Y Endo, Y Fujikawa, N Fujioka, M Fujita, R Goto, Y Han, S Hasegawa, T Hashimoto, S H Hayakawa, T Hayakawa, E Hayata, K Hicks, E Hirose, M Hirose, R Honda, K Hoshino, S Hoshino, K Hosomi, S H Hwang, Y Ichikawa, M Ichikawa, M Ieiri, K Imai, K Inaba, Y Ishikawa, A Iskendir, H Ito, K Ito, W S Jung, S Kanatsuki, H Kanauchi, A Kasagi, T Kawai, M H Kim, S H Kim, S Kinbara, R Kiuchi, H Kobayashi, K Kobayashi, T Koike, A Koshikawa, J Y Lee, J W Lee, T L Ma, S Y Matsumoto, M Minakawa, K Miwa, A T Moe, T J Moon, M Moritsu, Y Nagase, Y Nakada, M Nakagawa, D Nakashima, K Nakazawa, T Nanamura, M Naruki, A N L Nyaw, Y Ogura, M Ohashi, K Oue, S Ozawa, J Pochodzalla, S Y Ryu, H Sako, Y Sasaki, S Sato, Y Sato, F Schupp, K Shirotori, M M Soe, M K Soe, J Y Sohn, H Sugimura, K N Suzuki, H Takahashi, T Takahashi, Y Takahashi, T Takeda, H Tamura, K Tanida, A M M Theint, K T Tint, Y Toyama, M Ukai, E Umezaki, T Watabe, K Watanabe, T O Yamamoto, S B Yang, C S Yoon, J Yoshida, M Yoshimoto, D H Zhang, Z Zhang|
The lambda particle is the lightest hyperon which contains one strange quark. The interaction between lambda particles is one of the most important inputs for the structure of neutron stars, and it plays a major role in gravitational waves from the merger of neutron stars and in r-process nucleosynthesis. Because the lambda particle is short-lived, studying the structure of double lambda hypernuclei is critical to determining the interaction between two lambda particles. This paper reported on the successful production of a double hypernucleus of 11ΛΛBe. The experiment was performed at J-PARC by combining the emulsion technique and high-resolution spectrometers of charged particles. Even though seven events had previously been reported for the production of double hypernuclei, the nuclide of the produced hypernuclei had been uniquely identified in only one case. The present study constitutes the second case in which nuclides were successfully identified. The experimental data had much higher statistics than in previous measurements, and the ΛΛ binding energy ΔBΛΛ could be determined with higher precision. From these data, it was confirmed that the attraction between Λ particles was significantly weaker than that between nucleons. Moreover, it was determined that the value of ΔBΛΛ of 11ΛΛBe was significantly different from that of 6ΛΛHe, indicating that the value of ΔBΛΛ depended on the core nucleus in a hypernucleus. These results significantly improve our understanding of hyperon-hyperon interactions. It was therefore determined that this article deserves the Outstanding Paper Award of the Physical Society of Japan.
|Title of Article||Superconductivity in Ca1-xLaxFeAs2: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds|
|Journal||J. Phys. Soc. Jpn. 82, 123702 (2013)|
|Authors||Naoyuki Katayama, Kazutaka Kudo, Seiichiro Onari, Tasuku Mizukami, Kento Sugawara, Yuki Sugiyama, Yutaka Kitahama, Keita Iba, Kazunori Fujimura, Naoki Nishimoto, Minoru Nohara, and Hiroshi Sawa|
Following the discovery of iron-pnictide superconductors (Tc~26 K) by Hosono's group, tremendous efforts have been devoted to synthesizing new superconductors with similar crystal structures and higher superconducting transition temperatures (Tc). The highest Tc in this class of materials has increased to 55 K. The following research aimed at increasing Tc and developing new structures to investigate the relationship between the superconductivity mechanism and electronic dimensionality. For this latter purpose, various spacer layers between FeAs layers were developed.
|Title of Article||Superconductivity of Au-Ge-Yb Approximants with Tsai-type Clusters|
|Journal||J. Phys. Soc. Jpn. 84, 023705 (2015)|
|Author||Kazuhiko Deguchi, Mika Nakayama, Shuya Matsukawa, Keiichiro Imura, Katsumasa Tanaka, Tsutomu Ishimasa, and Noriaki K. Sato|
The development of new superconductors and the elucidation of their non-trivial superconducting mechanisms have been vigorously studied globally. In particular, the following questions related to this area of research have been posed: "Does superconductivity appear in quasi crystals without crystal translational symmetry?" and "What is the mechanism of superconductivity?" Studies have been conducted to answer these perplexing questions.
|Title of Article||Anomaly Polynomial of General 6D SCFTs|
|Journal||Prog. Theor. Exp. Phys. 2014, 103B07 (2014)|
|Authors||Kantaro Ohmori, Hiroyuki Shimizu, Yuji Tachikawa, Kazuya Yonekura|
In this study, the authors developed a method to obtain anomaly polynomials systematically in general six-dimensional N = (2,0) and N = (1,0) superconformal field theories (SCFT), and they demonstrated this in many concrete examples. The study of this type of six-dimensional SCFT is important in both string theory and quantum field theory. It often appears in string theory, as it is realized on a six-dimensional object called an M5-brane in M-theory, which is considered to be a unified theory of string theory. Furthermore, it has remarkable properties with profound applications. For example, dualities in some four-dimensional gauge theories can be derived by compactifying this six-dimensional theory to four dimensions. However, in general, analysis of this theory is extremely difficult, as no reliable weakly coupled description exists. Even the Lagrangian has not been written down in a covariant form because it contains a rank-2 antisymmetric tensor field with a self-dual field strength. The major achievement of this study is that it succeeds in determining the structure of an anomaly by circumventing all these difficulties.
|Title of Article||Quantum Thermal Hall Effect in a Time-Reversal-Symmetry-Broken Topological Superconductor in Two Dimensions: Approach from Bulk Calculations|
|Journal||J. Phys. Soc. Jpn. 82, 023602 (2013)|
|Authors||Hiroaki Sumiyoshi and Satoshi Fujimoto|
This study examined the thermal Hall conductivity (THC) of two-dimensional topological superconductors. The authors derived the formula of THC from the Bogoliubov-de Gennes (BdG) equation and showed that its coefficient is given by half of the Chern number, that is, it is quantized to one-half of that in the quantum Hall system. This half quantization itself was predicted by other authors based on the picture of the Majorana edge state. The present work is original in the derivation from the BdG equation that describes bulk states and in expressing the result using the bulk topological (Chern) number. The formula was derived without limiting the generality and is quite versatile, e.g., it is not restricted to two dimensions. In fact, the formula has been applied to three-dimensional chiral superconductors with a nodal gap [N. Yoshioka et al., J. Phys. Soc. Jpn. 87, 124602 (2018)]. As observed experimentally in a Kitaev magnet \alpha-RuCl3 [Y. Kasahara et al., Nature 559, 227 (2018)], half quantization of THC is currently a hot topic in the field of topological materials, to which this study made a significant contribution.