Related papers: Metastable cosmic strings
New physics beyond the Standard Model can give rise to stochastic gravitational-wave backgrounds, for example through cosmic strings. In this way, gravitational-wave searches with pulsar-timing arrays as well as existing and future laser…
The intersection of string theory with cosmology is unavoidable in the early universe, and its exploration may shine light on both fields. In this thesis, three papers at this intersection are presented and reviewed, with the aim of…
We interpret the recent NANOGrav results in terms of a stochastic gravitational wave background from metastable cosmic strings. The observed amplitude of a stochastic signal can be translated into a range for the cosmic string tension and…
If the Universe underwent a cosmic phase transition, it may have left behind a network of cosmic strings. When these strings arise from the breaking of a gauge symmetry, their decay produces a significant stochastic background of…
A realistic model of $SU(5) \times U(1)_{\chi}$, embedded in $SO(10)$ supersymmetric grand unified theory, is investigated for the emergence of a metastable cosmic string network. This network eventually decays via the Schwinger production…
Making use of the wealth of new observational data coming from the sky it is possible to constrain particle physics theories beyond the Standard Model. One way to do this is illustrated in this article: a subset of theories admits cosmic…
Composite topological structures such as superheavy "quasi-stable strings" (QSS) and "walls bounded by strings" (WBS) arise in realistic extensions of the Standard Model of high energy physics. We show that the gravitational radiation…
Recent work has established a method of constructing non-supersymmetric string models that are stable, with near-vanishing one-loop dilaton tadpoles and cosmological constants. This opens up the tantalizing possibility of realizing stable…
We discuss data analysis techniques that can be used in the search for gravitational wave bursts from cosmic strings. When data from multiple interferometers are available, we describe consistency checks that can be used to greatly reduce…
We discuss $E_6$ based extensions of the Standard Model (SM) containing two varieties of superheavy metastable cosmic strings (CSs) that respectively have neutral and electrically charged current carriers. We employ an extended version of…
Cosmic superstring loops generically contain strings of different tensions that meet at Y-junctions. These loops evolve non-periodically in time, and have cusps and kinks that interact with the junctions. We study the effect of junctions on…
It has been speculated that cosmic string networks could produce ultra-high energy cosmic rays as a by-product of their evolution. By making use of recent work on the evolution of such networks, it will be shown that the flux of cosmic rays…
Gravitational waves from cosmic strings are generated in the first fractions of a second after the Big Bang, potentially providing a unprecedented probe of the early universe. We discuss the key dynamical processes underlying calculations…
We construct a realistic supersymmetric model for superheavy metastable cosmic strings (CSs) that can be investigated in the current pulsar timing array (PTA) experiments. It is based on shifted $\mu$-hybrid inflation in which the symmetry…
Flat directions are a generic feature of the scalar potential in supersymmetric gauge field theories. They can arise, for example, from D-terms associated with an extra abelian gauge symmetry. Even when supersymmetry is broken softly, there…
The predictions of the inflationary LCDM paradigm match today's high-precision measurements of the cosmic microwave background anisotropy extremely well. The same data put tight limits on other sources of anisotropy. Cosmic strings are a…
Progress on string theory in curved spacetimes since 1992 are reviewed. After a short introduction on strings in Minkowski and curved spacetimes, we focus on strings in cosmological spacetimes. The classical behaviour of strings in FRW and…
We discuss the appearance of topological structures from the spontaneous breaking of $E_6$ to the Standard Model via its maximal subgroup $SO(10) \times U(1)_\psi$. They include dumbbells, metastable strings, as well as domain walls bounded…
The cosmic string is a useful probe of the early Universe and may give us a clue to physics at high energy scales where any artificial particle accelerators cannot reach. Although one of the most promising tools is the cosmic microwave…
We present projected constraints on the cosmic string tension, $G\mu/c^2$, that could be achieved by future gravitational wave detection experiments and express our results as semi-analytic relations of the form $G\mu(\Omega_{\rm…