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A new relaxion mechanism is proposed, where a small electroweak scale is preferably selected earlier than the larger one due to potential instability, different from previously proposed stopping mechanisms by either Hubble friction from increasing periodic barrier or thermal friction from gauge boson productions. A sub-Planckian field excursion of axion can be achieved without violating the bound on the e-folding number from quantum gravity consideration, and our relaxion can be identified as QCD axion, preserving the Peccei-Quinn solution to the strong CP problem as well as making up all the cold dark matter in our current Universe. |
