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The configuration of typical highly excited (M >> M_s ~ (alpha')^{-1/2}) string states is considered as the string coupling g is adiabatically increased. The size distribution of very massive single string states is studied and the mass…

High Energy Physics - Theory · Physics 2009-10-31 Thibault Damour , Gabriele Veneziano

In string theory, the traditional picture of a Universe that emerges from the inflation of a very small and highly curved space-time patch is a possibility, not a necessity: quite different initial conditions are possible, and not…

High Energy Physics - Theory · Physics 2017-06-01 M. Gasperini , G. Veneziano

Cosmic superstrings are produced towards the end of the brane inflation. If the string tension is low enough, loops tend to be relatively long-lived. The resultant string network is expected to contain many loops which are smaller than…

Astrophysics · Physics 2007-09-10 David F. Chernoff , S. -H. Henry Tye

We investigate cosmic strings arising from a hierarchical gauge symmetry breaking sequence, $\mathrm{SU}(2) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1)' \rightarrow \text{Nothing}$. This…

High Energy Physics - Phenomenology · Physics 2025-06-19 Akifumi Chitose , Masahiro Ibe , Satoshi Shirai , Yaxuan Wen

We derive analytic expressions for the interaction energy between two general $U(1)$ cosmic strings as the function of their relative orientation and the ratio of the coupling constants in the model. The results are relevant to the…

High Energy Physics - Phenomenology · Physics 2009-10-28 L. M. A. Bettencourt , R. J. Rivers

We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as…

Astrophysics · Physics 2009-07-22 Robert H. Brandenberger , Tomo Takahashi , Masahide Yamaguchi

There is an ongoing debate in cosmology about the value of the length scale at which ``homogeneity'' in the matter distribution is reached or even if such a scale exists. In the wake of this debate, we intend in this letter to clarify the…

Astrophysics · Physics 2009-10-31 Jose Gaite , Alvaro Dominguez , Juan Perez-Mercader

We study the production of loops in the cosmic string network in the expanding background by means of a numerical simulation exact in the flat-spacetime limit and first-order in the expansion rate. We find an initial regime characterized by…

Astrophysics · Physics 2008-11-26 Ken D. Olum , Vitaly Vanchurin

We follow the evolution of galaxy systems in numerical simulation. Our goal is to understand the role of density perturbations of various scales in the formation and evolution of the cosmic web. We perform numerical simulations with the…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-28 I. Suhhonenko , J. Einasto , L. J. Liivamägi , E. Saar , M. Einasto , G. Hütsi , V. Müller , A. A. Starobinsky , E. Tago , E. Tempel

This paper presents a compilation of clustering results taken from the literature for galaxies with highly enhanced (SFR [30-10^3] Msun/yr) star formation activity observed in the redshift range z=[0-3]. We show that, irrespective of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Manuela Magliocchetti , Andrea Lapi , Mattia Negrello , Gianfranco De Zotti , Luigi Danese

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…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Xavier Siemens , Jolien Creighton , Irit Maor , Saikat Ray Majumder , Kipp Cannon , Jocelyn Read

We evolve the network of global strings in the matter-dominated universe by means of numerical simulations. The existence of the scaling solution is confirmed as in the radiation-dominated universe but the scaling parameter $\xi$ takes a…

High Energy Physics - Phenomenology · Physics 2009-12-30 Masahide Yamaguchi , Jun'ichi Yokoyama , M. Kawasaki

With no free parameter (except the string scale $M_S$), dynamical flux compactification in Type IIB string theory determines both the cosmological constant (vacuum energy density) $\Lambda$ and the Planck mass $M_P$ in terms of $M_S$, thus…

High Energy Physics - Theory · Physics 2018-03-19 S. -H. Henry Tye

The implications of string theory for understanding the dimension of uncompactified spacetime are investigated. Using recent ideas in string cosmology, a new model is proposed to explain why three spatial dimensions grew large. Unlike the…

High Energy Physics - Theory · Physics 2010-11-01 Gerald B. Cleaver , Philip J. Rosenthal

We study cosmic strings in the complex symmetron model, a scalar-tensor theory with a spontaneously broken local $U(1)$ symmetry in low matter density regions. Using numerical simulations, we show that these strings preferentially attach to…

High Energy Physics - Phenomenology · Physics 2025-08-19 Ali Nezhadsafavi , Levon Pogosian

We argue that, for generic string compactifications, dark energy is likely to signal the beginning of the end of our universe, perhaps even through decompactification, with possible implications for the cosmological coincidence problem.…

High Energy Physics - Theory · Physics 2021-10-27 Francesc Cunillera , Antonio Padilla

We examine the structure of baryonic wakes in the cosmological fluid which would form behind GUT-scale cosmic strings at early times (redshifts z > 100) in a neutrino-dominated universe. We show, using simple analytical arguments as well as…

Astrophysics · Physics 2009-10-30 Tom Abel , Albert Stebbins , Peter Anninos , Michael L. Norman

In string gas cosmology, the extra dimensions of the underlying theory are kept at a microscopic scale by a gas of strings. In the matter-dominated era, however, dust pressure can lead to oscillations of the extra dimensions and to…

High Energy Physics - Theory · Physics 2009-11-05 Francesc Ferrer

We present dynamical and structural scaling relations of quiescent galaxies at z=2, including the dynamical mass-size relation and the first constraints on the fundamental plane (FP). The backbone of the analysis is a new, very deep…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 S. Toft , A. Gallazzi , A. Zirm , M. Wold , S. Zibetti , C. Grillo , A. Man

Appearance of cosmic strings in the early Universe is a common manifestation of new physics typically linked to some high energy scale. In this paper, we discuss a different situation, where a model underlying cosmic string formation is…

High Energy Physics - Phenomenology · Physics 2022-02-02 William T. Emond , Sabir Ramazanov , Rome Samanta