TY - JOUR
T1 - Enhanced photon coupling of ALP dark matter adiabatically converted from the QCD axion
AU - Ho, Shu Yu
AU - Saikawa, Ken'Ichi
AU - Takahashi, Fuminobu
N1 - Funding Information:
We thank Georg Raffelt and Andreas Ringwald for useful comments. F.T. thanks the hospitality of MIT Center for Theoretical Physics where a part of this work was done. K.S. acknowledges partial support by the Deutsche Forschungsgemeinschaft through Grant No. EXC 153 (Excellence Cluster “Universe”) and Grant No. SFB 1258 (Collaborative Research Center “Neutrinos, Dark Matter, Messengers”) as well as by the European Union through Grant No. H2020-MSCA-ITN-2015/674896 (Innovative Training Network “Elusives”). This work is partially supported by JSPS KAKENHI Grant Numbers JP15H05889 (F.T.), JP15K21733 (F.T.), JP17H02878 (F.T.), and JP17H02875 (F.T.), Leading Young Researcher Overseas Visit Program at Tohoku University (F.T.), and by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan (F.T.).
Publisher Copyright:
© 2018 IOP Publishing Ltd and Sissa Medialab.
PY - 2018/10/22
Y1 - 2018/10/22
N2 - We revisit the adiabatic conversion between the QCD axion and axion-like particle (ALP) at level crossing, which can occur in the early universe as a result of the existence of a hypothetical mass mixing. This is similar to the Mikheyev-Smirnov-Wolfenstein effect in neutrino oscillations. After refining the conditions for the adiabatic conversion to occur, we focus on a scenario where the ALP produced by the adiabatic conversion of the QCD axion explains the observed dark matter abundance. Interestingly, we find that the ALP decay constant can be much smaller than the ordinary case in which the ALP is produced by the realignment mechanism. As a consequence, the ALP-photon coupling is enhanced by a few orders of magnitude, which is advantageous for the future ALP and axion-search experiments using the ALP-photon coupling.
AB - We revisit the adiabatic conversion between the QCD axion and axion-like particle (ALP) at level crossing, which can occur in the early universe as a result of the existence of a hypothetical mass mixing. This is similar to the Mikheyev-Smirnov-Wolfenstein effect in neutrino oscillations. After refining the conditions for the adiabatic conversion to occur, we focus on a scenario where the ALP produced by the adiabatic conversion of the QCD axion explains the observed dark matter abundance. Interestingly, we find that the ALP decay constant can be much smaller than the ordinary case in which the ALP is produced by the realignment mechanism. As a consequence, the ALP-photon coupling is enhanced by a few orders of magnitude, which is advantageous for the future ALP and axion-search experiments using the ALP-photon coupling.
KW - axions
KW - dark matter theory
KW - particle physics - cosmology connection
KW - physics of the early universe
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U2 - 10.1088/1475-7516/2018/10/042
DO - 10.1088/1475-7516/2018/10/042
M3 - Article
AN - SCOPUS:85056112527
SN - 1475-7516
VL - 2018
JO - Journal of Cosmology and Astroparticle Physics
JF - Journal of Cosmology and Astroparticle Physics
IS - 10
M1 - 042
ER -