Axions and the strong CP problem

Jihn E. Kim and Gianpaolo Carosi
Rev. Mod. Phys. 82, 557 – Published 4 March 2010; Erratum Rev. Mod. Phys. 91, 049902 (2019)

Abstract

Current upper bounds on the neutron electric dipole moment constrain the physically observable quantum chromodynamic (QCD) vacuum angle |θ¯|1011. Since QCD explains a great deal of experimental data from the 100MeV to the TeV scale, it is desirable to explain this smallness of |θ¯| in the QCD framework; this is the strong CP problem. There now exist two plausible solutions to this problem, one of which leads to the existence of a very light axion. The axion decay constant window, 109Fa1012GeV for an O(1) initial misalignment angle θ1, has been obtained from astrophysical and cosmological data. For Fa1012GeV with θ1<O(1), axions may constitute a significant fraction of the dark matter of the universe. The supersymmetrized axion solution of the strong CP problem introduces its superpartner the axino, which might have affected the evolution of the Universe significantly. The very light axion (theory, supersymmetrization, and models) using recent particle, astrophysical, and cosmological data, and present prospects for its discovery is reviewed here.

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    DOI:https://doi.org/10.1103/RevModPhys.82.557

    ©2010 American Physical Society

    Erratum

    Erratum: Axions and the strong CP problem [Rev. Mod. Phys. 82, 557 (2010)]

    Jihn E. Kim and Gianpaolo Carosi
    Rev. Mod. Phys. 91, 049902 (2019)

    Authors & Affiliations

    Jihn E. Kim*

    • Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Korea

    Gianpaolo Carosi

    • Physical Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA

    • *jekim@ctp.snu.ac.kr
    • carosi2@llnl.gov

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    Issue

    Vol. 82, Iss. 1 — January - March 2010

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