TY - JOUR

T1 - Cosmological abundance of the QCD axion coupled to hidden photons

AU - Kitajima, Naoya

AU - Sekiguchi, Toyokazu

AU - Takahashi, Fuminobu

N1 - Funding Information:
This work is supported by Grant-in-Aid for JSPS Fellows (N.K.), JSPS KAKENHI Grant Numbers JP15H02082 (T.S.), JP15H05889 (F.T.), JP15K21733 (F.T.), JP26247042 (F.T.), JP17H02875 (F.T.), JP17H02878 (F.T.), and by World Premier International Research Center Initiative (WPI Initiative), MEXT , Japan (F.T.).
Publisher Copyright:
© 2018 The Authors

PY - 2018/6/10

Y1 - 2018/6/10

N2 - We study the cosmological evolution of the QCD axion coupled to hidden photons. For a moderately strong coupling, the motion of the axion field leads to an explosive production of hidden photons by tachyonic instability. We use lattice simulations to evaluate the cosmological abundance of the QCD axion. In doing so, we incorporate the backreaction of the produced hidden photons on the axion dynamics, which becomes significant in the non-linear regime. We find that the axion abundance is suppressed by at most O(102) for the decay constant fa=1016GeV, compared to the case without the coupling. For a sufficiently large coupling, the motion of the QCD axion becomes strongly damped, and as a result, the axion abundance is enhanced. Our results show that the cosmological upper bound on the axion decay constant can be relaxed by a few hundred for a certain range of the coupling to hidden photons.

AB - We study the cosmological evolution of the QCD axion coupled to hidden photons. For a moderately strong coupling, the motion of the axion field leads to an explosive production of hidden photons by tachyonic instability. We use lattice simulations to evaluate the cosmological abundance of the QCD axion. In doing so, we incorporate the backreaction of the produced hidden photons on the axion dynamics, which becomes significant in the non-linear regime. We find that the axion abundance is suppressed by at most O(102) for the decay constant fa=1016GeV, compared to the case without the coupling. For a sufficiently large coupling, the motion of the QCD axion becomes strongly damped, and as a result, the axion abundance is enhanced. Our results show that the cosmological upper bound on the axion decay constant can be relaxed by a few hundred for a certain range of the coupling to hidden photons.

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U2 - 10.1016/j.physletb.2018.04.024

DO - 10.1016/j.physletb.2018.04.024

M3 - Article

AN - SCOPUS:85046677870

VL - 781

SP - 684

EP - 687

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

ER -