Gravitating (field theoretical) cosmic (p,q)-superstrings

We study field theoretical models for cosmic (p,q)-superstrings in a curved space-time. We discuss both string solutions, i.e. solutions with a conical deficit, but also so-called Melvin solutions, which have a completely different asymptotic behaviour. We show that globally regular gravitating (p,q)-strings exist only in a finite domain of the parameter space and study the dependence of the domain of existence on the parameters in the model. We find that due to the interaction between strings, the parameter range where string solution exist is wider than for non-interacting strings.Comment: 15 pages including 8 figure

Nielsen-Olesen strings in Supersymmetric models

We investigate the behaviour of a model with two oppositely charged scalar fields. In the Bogomol'nyi limit this may be seen as the scalar sector of N=1 supersymmetric QED, and it has been shown that cosmic strings form. We examine numerically the model out of the Bogomol'nyi limit, and show that this remains the case. We then add supersymmetry-breaking mass terms to the supersymmetric model, and show that strings still survive. Finally we consider the extension to N=2 supersymmetry with supersymmetry-breaking mass terms, and show that this leads to the formation of stable cosmic strings, unlike in the unbroken case.Comment: 7 pages, 2 figues, uses revtex4; minor typos corrected; references adde

Gravitating Semilocal strings

We discuss the properties of semilocal strings minimally coupled to gravity. Semilocal strings are solutions of the bosonic sector of the Standard Model in the limit $\sin^2\theta_W=1$ (where $\theta_W$ is the Weinberg angle) and correspond to embedded Abelian-Higgs strings for a particular choice of the scalar doublet. We focus on the limit where the gauge boson mass is equal to the Higgs boson mass such that the solutions fulfill the Bogomolnyi-Prasad-Sommerfield (BPS) bound.Comment: Contribution to the Proceedings of the Spanish Relativity Meeting (ERE) 2009, Bilbao, Spai

CMB polarization power spectra contributions from a network of cosmic strings

We present the first calculation of the possible (local) cosmic string contribution to the cosmic microwave background polarization spectra from simulations of a string network (rather than a stochastic collection of unconnected string segments). We use field-theory simulations of the Abelian Higgs model to represent local U(1) strings, including their radiative decay and microphysics. Relative to previous estimates, our calculations show a shift in power to larger angular scales, making the chance of a future cosmic string detection from the B-mode polarization slightly greater. We explore a future ground-based polarization detector, taking the CLOVER project as our example. In the null hypothesis (that cosmic strings make a zero contribution) we find that CLOVER should limit the string tension mu to G mu < 0.12x10(-6) (where G is the gravitational constant), above which it is likely that a detection would be possible