Axionic domain wall production during inflation

Abstract It is shown that quantum fluctuations of the axion field produced during inflation may lead to formation of exponentially big axionic domain walls even in the simplest ( N = 1) axion models. Unlike the axionic walls previously discussed in the literature, the walls produced during inflation are exponentially (or even infinitely) large. Similar walls appear also in other theories of pseudo-Goldstone bosons. Possible cosmological consequences of our results are discussed.