Partial restoration of chiral symmetry in nucleus observed in pionic atoms

ORAL

Abstract

We have quantitatively evaluated chiral condensate, the order parameter of the chiral symmetry, in nuclear matter and found that it is reduced to 77+-2% in the nuclear medium compared to vacuum. We have performed high-precision spectroscopy experiments of pion tin atoms at the RIKEN RI Beam Factory to derive chiral condensation. The obtained spectra were analyzed to determine the interaction between pions and nuclei. The results show that the s-wave interaction is stronger in the nucleus than in the vacuum. This enhancement is due to the wavefunction renormalization of the medium effect. From this, it is possible to estimate the medium effect inversely and link it to the partial recovery of the chiral symmetry. Taking into account the latest nuclear density distribution, spectroscopic factors, and residual interactions, the magnitude of chiral condensate in the nuclear medium is quantitatively evaluated and successfully estimated with errors for the first time in the world in a high-density medium. Future plans will also be discussed.

*The experiment was performed at the RI Beam Factory, operated by RIKEN Nishina Center and CNS, University of Tokyo.This work is partly supported by the MEXT Grant-in-Aid for Scientific Research on Innovative Areas (nos. JP22105517, JP24105712 and JP15H00844), JSPS Grant-in-Aid for Scientific Research (B) (nos. JP16340083 and JP18H01242), (A) (no. JP16H02197) and (C) (nos. JP16K05355 and JP24540274), Grant-in-Aid for Early-Career Scientists (no. JP19K14709), Grant-in-Aid for JSPS Research Fellow (no. JP12J08538), JSPS Fund for the Promotion of Joint International Research (Fostering Joint International Research (B); no. JP20KK0070), Institute for Basic Science (IBS-R031-D1), the Bundesministerium für Bildung und Forschung, the National Science Foundation through grant no. Phys-0758100, and the Joint Institute for Nuclear Astrophysics (grants nos. Phys-0822648 and PHY-1430152; JINA Center for the Evolution of the Elements).

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Publication: Nature Physics 19 (2023) 788-793, https://doi.org/10.1038/s41567-023-02001-x

Presenters

  • Kenta Itahashi

    • RIKEN Nishina Center

Authors

  • Kenta Itahashi

    • RIKEN Nishina Center

  • Takahiro Nishi

    • RIKEN Nishina Center

  • Deuksoon Ahn

    • Center for Exotic Nuclear Studies, IBS
    • RIKEN Nishina Center, Center for Exotic Nuclear Study IBS

  • Georg P Berg

    • University of Notre Dame

  • Masanori Dozono

    • RIKEN Nishina Center
    • Department of Physics, Kyoto University
    • Kyoto University
    • Graduate School of Science, Kyoto University
    • Kyoto University, Japan

  • Daijiro Etoh

    • Department of Physics, Tohoku University

  • Hiroyuki Fujioka

    • Department of Physics, Tokyo Institute of Technology
    • Tokyo Institute of Technology

  • Naoki Fukuda

    • RIKEN Nishina Center
    • RIKEN

  • Nobuhisa Fukunishi

    • RIKEN Nishina Center

  • Hans Geissel

    • GSI Helmholtzzentrum für Schwerionenforschung GmbH

  • Emma Haettner

    • GSI Helmholtzzentrum für Schwerionenforschung GmbH

  • Tadashi Hashimoto

    • ASRC, JAEA, Japan

  • Ryugo S Hayano

    • Department of Physics, The University of Tokyo

  • Satoru Hirenzaki

    • Department of Physics, Nara Women's University

  • Hiroshi Horii

    • Department of Physics, The University of Tokyo

  • Natsumi Ikeno

    • Department of Life and Environmental Agricultural Sciences, Tottori University
    • Tottori University

  • Naoto Inabe

    • RIKEN Nishina Center

  • Masahiko Iwasaki

    • RIKEN Nishina Center

  • Daisuke Kameda

    • RIKEN Nishina Center

  • Keichi Kisamori

    • CNS, The University of Tokyo

  • Yu Kiyokawa

    • CNS, The University of Tokyo

  • Toshiyuki Kubo

    • RIKEN Nishina Center

  • Kensuke Kusaka

    • RIKEN Nishina Center

  • Masafumi Matsushita

    • CNS, The University of Tokyo

  • Shin'ichiro Michimasa

    • CNS, The University of Tokyo
    • The University of Tokyo
    • Center for Nuclear Study, the University of Tokyo
    • Center for Nuclear Study, The University of Tokyo
    • CNS, University of Tokyo
    • CNS, University of Tokyo, Japan

  • Go Mishima

    • Department of Physics, The University of Tokyo

  • Hiroyuki Miya

    • RIKEN Nishina Center

  • Daichi Murai

    • RIKEN Nishina Center

  • Hideko Nagahiro

    • Nara Women's University
    • Nara Women's University / RCNP Osaka University

  • Megumi Niikura

    • RIKEN Nishina Center
    • High Energy Nuclear Physics Lab, RIKEN

  • Naoko Nose-Togawa

    • RCNP, Osaka University

  • Shinsuke Ota

    • Research Center for Nuclear Physics, Osaka University
    • RCNP, Osaka University

  • Naruhiko Sakamoto

    • RIKEN Nishina Center
    • RIKEN

  • Kimiko Sekiguchi

    • Department of Physics, Tokyo Institute of Technology

  • Yuta Shiokawa

    • Department of Physics, Tohoku University

  • Hiroshi Suzuki

    • RIKEN Nishina Center
    • RIKEN

  • Ken Suzuki

    • GSI Helmholtzzentrum für Schwerionenforschung GmbH

  • Motonobu Takaki

    • CNS, The University of Tokyo

  • Hiroyuki Takeda

    • RIKEN Nishina Center
    • RIKEN

  • Yoshiki K Tanaka

    • RIKEN CPR

  • Tomohiro Uesaka

    • RIKEN Nishina Center
    • RNC
    • RIKEN

  • Yasumori Wada

    • Department of Physics, Tohoku University

  • Atomu Watanabe

    • Department of Physics, Tohoku University

  • Yuni N Watanabe

    • Department of Physics, The University of Tokyo

  • Helmut Weick

    • GSI Helmholtzzentrum für Schwerionenforschung GmbH

  • Hiroki Yamakami

    • Department of Physics, Kyoto University

  • Yoshiyuki Yanagisawa

    • RIKEN Nishina Center
    • RIKEN

  • Koichi Yoshida

    • RIKEN Nishina Center
    • RIKEN