DEFECT FORMATION IN FIRST-ORDER PHASE-TRANSITIONS WITH DAMPING

Within the context of first order phase transitions in the early unive rse, we study the influence of a coupling between the [global U(1)] sc alar driving the transition and the rest of the matter content of the theory. The effect of the coupling on the scalar is simulated by intro ducing a damping term in its equations of motion. Following a previous paper, in which we studied the influence that this coupling has on in dividual bubble collisions and on topological defect formation, we pro ceed here to quantify the impact these effects have on the number of d efects created per nucleated bubble, n(d). To a good accuracy, we find that n(d) goes through two different regimes as we increase the value of the damping coefficient gamma. The first regime has n(d) changing as n(d) proportional to gamma(-1/2), whereas for the second one n(d) p roportional to gamma(-3/4). In a first approximation, the divide betwe en the two regimes is estimated to be at values gamma such that gamma delta(m) similar to 2R (where R and delta(m)are the bubble radius and wall thickness, respectively).