Reconnection of colliding cosmic strings

Abstract

For vortex strings in the Abelian Higgs model and D-strings in superstring theory, both of which can be regarded as cosmic strings, we give analytical study of reconnection (recombination, inter-commutation) when they collide, by using effective field theories on the strings. First, for the vortex strings, via a string sigma model, we verify analytically that the reconnection is classically inevitable for small collision velocity and small relative angle. Evolution of the shape of the reconnected strings provides an upper bound on the collision velocity in order for the reconnection to occur. These analytical results are in agreement with previous numerical results. On the other hand, reconnection of the D-strings is not classical but probabilistic. We show that a quantum calculation of the reconnection probability using a D-string action reproduces the nonperturbative nature of the worldsheet results by Jackson, Jones and Polchinski. The difference on the reconnection -classically inevitable for the vortex strings while quantum mechanical for the D-strings -is suggested to originate from the difference between the effective field theories on the strings.

Kinematic constraints on formation of bound states of cosmic strings: Field theoretical approach

“…Analytically, right-angle scattering after a head-on collision is understood at critical coupling (β = 1) [27], in terms of geodesic motion in the moduli space approximation. This approach was introduced for the first time in the context of monopole scattering [28] but has been recently re-employed in studies of strings in more complicated models [29,30]. After intercommutation, here the string segments align almost parallel before coming together.…”

Universal Reconnection of Non-Abelian Cosmic Strings

“…The moduli matrix formalism [4] gives a well-defined set of moduli coordinates, and with that the analysis of the motion is quite simple and robust. Our results will be a basis for further analyses on coupling to gravity and application to cosmology, and possible comparison against cosmic super/D-strings [6,12,13].…”

“…As in the case of Abelian-Higgs model, numerical simulations [9,10] showed robustness of the reconnection even for high energy collisions. We hope that, in the future observation, this universality may help for distinguishing solitonic strings from cosmic superstrings/D-branes which have lower reconnection probabilities [6,13]. The moduli matrix formalism has opened up new paths to analyze BPS solitons.…”

“…reconnection probability is unity) is universal. The inevitable reconnection of local strings in Abelian Higgs model [5] (see also [6]) has been known for decades, and for non-Abelian local strings in U (N C ) gauge theories with N F (= N C ) flavors, this universality was found in [7] by a topological argument. Here, via a different logic and explicit computations, we show the concrete dynamics of the inevitable reconnection (note that [7] does not describe dynamics).…”

Reconnection of non-abelian cosmic strings

“…In contrast, fundamental strings interact with probability P ∼ g 2 s , where the functional dependence on the angle of incidence and relative velocity of the strings was determined in [15,16]. Similarly, D-strings may also pass through each other, reconnecting with probability P < 1 [16,17]. A reduced probability for reconnection affects the scaling solution for the string network, resulting in a larger concentration of strings in the sky [18,19,2].…”