Collision of cosmic superstrings

We study the formation of three-string junctions between $(p,q)$-cosmic superstrings, and collisions between such strings and show that kinematic constraints analogous to those found previously for collisions of Nambu-Goto strings apply here too, with suitable modifications to take account of the additional requirements of flux conservation. We examine in detail several examples involving collisions between strings with low values of $p$ and $q$, and also examine the rates of growth or shrinkage of strings at a junction. Finally, we briefly discuss the formation of junctions for strings in a warped space, specifically with a Klebanov-Strassler throat, and show that similar constraints still apply with changes to the parameters taking account of the warping and the background flux.

Figure 1

Schematic representation of the different cases considered in the text, all with ${\overline{\mu }}_1={\overline{\mu }}_2$ and for $(p_1,{\tilde{q}}_1)$ fixed (and positive). Note that the formation of a $y$-link in “case A3” is equivalent (by rotation by $\pi /2$) to a considering the formation of an $x$-link in “case A4.”

Figure 2

$⟨{\dot{s}}_i⟩$ as a function of $g_s$. Red, upper curve: $i=1$. Blue, lower curve: $i=3$, green, middle curve: $i=2$.