Evaluation of double-beta decay nuclear matrix elements using generator coordinate method

• Project Area: Revealing the history of the universe with underground particle and nuclear research
• Project/Area Number: 17H05194
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: University of Tsukuba
• Principal Investigator: 日野原 伸生 筑波大学, 計算科学研究センター, 助教 (80511435)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
• Keywords: 二重ベータ崩壊 / 原子核構造 / 理論核物理 / 生成座標法

Outline of Annual Research Achievements

二重ベータ崩壊原子核行列要素の不定性の主要な要因の一つとなっている中性子ー陽子対相関の決定に向け、2017年度に定式化した、有限振幅法による準粒子乱雑位相近似計算のコード開発を行った。実装は軸対称変形が取り扱える原子核密度汎関数法計算コードHFBTHOと、米国ノースカロライナ大学で開発された中性子ー陽子チャネルの線形応答計算の有限振幅法コードをもとに行った。この方法によって準粒子乱雑位相近似の従来の解法である大次元行列対角化を行うことなく、原子核行列要素を並列化が可能な複素エネルギー面での二重積分によって、効率的に計算することが可能となった。
まずは小さいサイズの調和振動子基底の一粒子模型空間を設定し、48Caを含むpf殻原子核で二重複素積分によって池田和則を計算し、コードのチェックを行った。続いて基底状態間の二重ガモフテラー遷移強度およびニュートリノを2つ放出する二重ベータ崩壊の原子核行列要素計算を、アイソベクトルおよびアイソスカラーの中性子ー陽子対相関の強度を変えながら系統的に行い、中性子ー陽子対相関の結合定数依存性の分析を行った。アイソベクトル型中性子ー陽子対相関によってフェルミ型の原子核行列要素が抑制され、アイソスカラー中性子ー陽子対相関によってガモフ・テラー型の原子核行列要素の抑制が系統的に見られた。今後模型空間を大きくし、様々な原子核密度汎関数を用いた計算を系統的に行うことで、二重ベータ崩壊の実験値を大域的に再現する中性子ー陽子対相関の結合定数の決定を行うことが可能となった。

Research Progress Status

平成30年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

平成30年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] ノースカロライナ大学(米国)
• [Int'l Joint Research] ノースカロライナ大学(米国)
• [Journal Article] 原子核集団現象への平均場アプローチ (2019)
  • Author(s): 日野原 伸生
  • Journal Title: 原子核研究 Volume: 63 Supplement 1 Pages: 5-12
• [Journal Article] Low-lying collective excited states in nonintegrable pairing models based on the stationary-phase approximation to the path integral (2018)
  • Author(s): Ni Fang、Hinohara Nobuo、Nakatsukasa Takashi
  • Journal Title: Physical Review C Volume: 98 Issue: 6 Pages: 064327-064327
  • DOI: 10.1103/physrevc.98.064327
  • NAID: 120007128269
  • Peer Reviewed
• [Journal Article] Extending pairing energy density functional using pairing rotational moments of inertia (2018)
  • Author(s): Nobuo Hinohara
  • Journal Title: Journal of Physics G: Nuclear and Particle Physics Volume: 45 Issue: 2 Pages: 024004-024004
  • DOI: 10.1088/1361-6471/aa9f8b
  • Peer Reviewed
• [Presentation] Finite-amplitude method for double-beta decay nuclear matrix elements (2019)
  • Author(s): Nobuo Hinohara
  • Organizer: International Symposium on Revealing the history of the universe with underground particle and nuclear research 2019
  • Int'l Joint Research
• [Presentation] Double-beta decay nuclear matrix element using finite-amplitude method (2018)
  • Author(s): Nobuo Hinohara and Jonathan Engel
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research
• [Presentation] 二重ベータ崩壊原子核行列要素計算の現状 (2018)
  • Author(s): 日野原 伸生
  • Organizer: 「宇宙の歴史をひもとく地下素粒子原子核研究」京大・A班共催 二重ベータ崩壊若手研究会
  • Invited
• [Presentation] Finite-amplitude method for double-beta decay (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: Tsukuba-CCS workshop on “microscopic theories of nuclear structure and dynamics”,
  • Int'l Joint Research
• [Presentation] Nuclear collective excitation within finite-amplitude method (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: 10th international conference on Direct Reactions with Exotic Beams (DREB2018)
  • Int'l Joint Research
• [Presentation] 原子核集団現象への平均場アプローチ (2018)
  • Author(s): 日野原 伸生
  • Organizer: 第64回原子核三者若手夏の学校
  • Invited
• [Presentation] Neutron-proton DFT (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: The 4th workshop on many-body correlations in microscopic nuclear model (SADO2018)
• [Presentation] Nuclear density functional theory for collective excitation (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research / Invited
• [Presentation] Nuclear density functional theory for description of collective excitation (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: 10th China-Japan Joint Nuclear Physics Symposium (CJNP2018)
  • Int'l Joint Research / Invited
• [Presentation] Energy-weighted sum rule for nuclear density functional theory (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: 13th International Conference on Nucleus-Nucleus Collisions (NN2018)
  • Int'l Joint Research
• [Presentation] Binding-energy differences of even-even nuclei and pairing correlation (2018)
  • Author(s): Nobuo Hinohara
  • Organizer: 13th International Conference on Nucleus-Nucleus Collisions (NN2018)
  • Int'l Joint Research
• [Presentation] 生成座標法による二重ベータ崩壊原子核行列要素の評価 (2017)
  • Author(s): 日野原 伸生
  • Organizer: 新学術領域「宇宙の歴史をひもとく地下素粒子原子核研究」2017年領域研究会
  • Invited
• [Presentation] Application of generator coordinate method with neutron-proton pairing amplitudes to nuclear matrix elements (2017)
  • Author(s): Nobuo Hinohara
  • Organizer: MEDEX'17 (Matrix Elements for the Double beta decay EXperiments) meeting
  • Int'l Joint Research / Invited
• [Presentation] Nuclear matrix elements from generator coordinate method (2017)
  • Author(s): Nobuo Hinohara
  • Organizer: INT Program INT-17-2a Neutrinoless Double-beta Decay
  • Int'l Joint Research
• [Presentation] Generator coordinate method with neutron-proton pairing amplitudes for double-beta decay nuclear matrix elements (2017)
  • Author(s): Nobuo Hinohara
  • Organizer: XXXV Mazurian Lakes Conference on Physics
  • Int'l Joint Research
• [Presentation] Neutron-proton pairing and double-beta decay nuclear matrix element (2017)
  • Author(s): Nobuo Hinohara
  • Organizer: Conference on Neutrino and Nuclear Physics (CNNP2017)
  • Int'l Joint Research