Seminarium "Teoria cząstek elementarnych i kosmologia"

In this talk I will describe how topological defect formation and annihilation can be understood in a fully quantum formalism, albeit in a regime where self-interactions are negligible. This corresponds to the so-called spinodal instability phase of a quantum phase transition. I will introduce the relevant tools in a scalar 1+1 dimensional flat spacetime model where Z_2 symmetry is spontaneously broken, which generically leads to the formation of kinks and antikinks. I will calculate the number density of such objects as a function of time and show that it scales as t^{-1/2} in the late time limit (and independently of the details of the phase transition). This decay can be interpreted in terms of mutual annihilation of kink-antikink pairs. I will also discuss the extension of these methods to the case of asymmetric initial conditions, expanding and higher dimensional background spacetimes, as well as higher co-dimension topological defects.