ACTA

Chiral Symmetry Restoration in Nucleus Observed in Pionic Atoms

K. Itahashi^{a, b}, T. Nishi^a, D. Ahn^{a, c}, G.P.A. Berg^d, M. Dozono^a, D. Etoh^e, H. Fujioka^f, N. Fukuda^a, N. Fukunishi^a, H. Geissel^g, E. Haettner^g, T. Hashimoto^{b, h}, R.S. Hayanoⁱ, S. Hirenzaki^j, H. Horiiⁱ, N. Ikeno^k, N. Inabe^a, M. Iwasaki^{a, b}, D. Kameda^a, K. Kisamori^l, Y. Kiyokawa^l, T. Kubo^a, K. Kusaka^a, M. Matsushita^l, S. Michimasa^l, G. Mishimaⁱ, H. Miya^a, D. Murai^a, H. Nagahiro^j, M. Niikuraⁱ, N. Nose-Togawa^m, S. Ota^l, N. Sakamoto^a, K. Sekiguchi^e, Y. Shiokawa^e, H. Suzuki^a, K. Suzuki^{g, n}, M. Takaki^l, H. Takeda^a, Y.K. Tanaka^b, T. Uesaka^a, Y. Wada^e, A. Watanabe^e, Y.N. Watanabeⁱ, H. Weick^g, H. Yamakami^f, Y. Yanagisawa^a, K. Yoshida^a
^aNishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198, Japan
^bCluster for Pioneering Research, RIKEN, Wako, Saitama 351-0198, Japan
^cCenter for Exotic Nuclear Studies, Institute for Basic Science (IBS), Yuseong-gu, Daejeon 34126, Republic of Korea
^dDepartment of Physics and the Joint Institute for Nuclear Astrophysics Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, Indiana 46556, USA
^eDepartment of Physics, Tohoku University, Sendai, Miyagi 980-8578, Japan
^fDepartment of Physics, Kyoto University, Sakyo, Kyoto 606-8502, Japan
^gGSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany
^hAdvanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
ⁱDepartment of Physics, School of Science, University of Tokyo, Hongo 113-0033, Tokyo, Japan
^jDepartment of Physics, Nara Women's University, Kita-Uoya Nishimachi, Nara 630-8506, Japan
^kDepartment of Life and Environmental Agricultural Sciences, Faculty of Agriculture, Tottori University, Koyamacho-Minami, Tottori 680-8551, Japan
^lCenter for Nuclear Study, University of Tokyo, Wako, Saitama 351-0198, Japan
^mResearch Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan
ⁿRuhr-Universität Bochum, D-44801 Bochum, Germany

Full Text PDF

We conducted experimental and theoretical studies of chiral condensate in the nuclear medium through precision spectroscopy of pionic Sn atoms and subsequent analyses. The chiral condensate at ~60% of the nuclear saturation density is found to be reduced by 23±2% compared to that in the vacuum.

DOI:10.12693/APhysPolA.146.721
topics: chiral symmetry, pionic atoms, quantum chromodynamics (QCD), vacuum