Speaker
Wen Yin
Description
I show that the upper bound of the classical QCD axion window can be significantly relaxed with (not too) low-scale inflation. If the Gibbons-Hawking temperature during inflation is lower than the QCD scale and the inflation lasts long enough, the initial QCD axion misalignment angle follows the Bunch-Davies distribution. The distribution is peaked at the strong CP conserving minimum if there is no other light degree of freedom contributing to the strong CP phase. As a result, the axion can be the dark matter even for the mass much lighter than $\mu$eV. I also discuss some applications of the mechanism.
