Vilenkin, A. & Shellard, E.P.S., 1994. Cosmic strings and other topological defects, CUP.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to constant density fluctuations on small scales. If gravity waves make an important contribution to CMB anisotropies, h rms 10 Gamma5 and Omega GW 10 Gamma14 is expected. A gravity wave background of a similar flat spectrum is also predicted from cosmic strings (see section 10.4 of Vilenkin Shellard 1994). Here, the prediction is Omega GW 100 [G=c 2 ] Omega r ; 72) where is the mass per unit length. A viable string cosmology requires G=c 2 10 Gamma5 , so Omega GW 10 Gamma7 is expected much higher than the inflationary prediction. The part of the spectrum with periods of ....

Vilenkin, A. & Shellard, E.P.S., 1994. Cosmic strings and other topological defects, CUP.

....end by quantum tunneling of the whole domain wall, followed by thermalization of its energy. The resulting universe will therefore exhibit a hot big bang, and may conceivably resemble our universe. A comprehensive discussion of domain walls in cosmology is given by Vilenkin and Shel2 lard [3]. There has been a great deal of work on formation and dynamics of closed domain walls between domains of true and false vacuua the so called bubble walls including the possibility of budding off of new universes within a newly formed black hole. The present work differs from that work ....

Vilenkin, A. & Shellard, E., Cosmic Strings and other Topological Defects, (Cambridge University Press, 1994).

....the minimal radiation rate and suggest that fl 0 min = 39:003. PACS number(s) 98.80.Cq, 04.30.Db, 11.27. d Typeset using REVT E X 1 I. INTRODUCTION Cosmic strings are one dimensional topological defects that may have formed if the vacuum underwent a phase transition at very early times [1 4]. The resulting network of strings is of cosmological interest if the strings have a large enough mass per unit length, If G=c 2 10 Gamma6 , where G is Newton s constant and c is the speed of light (i.e. 10 22 g cm) then cosmic strings may be massive enough to have provided the ....

....strings may be massive enough to have provided the density perturbations necessary to produce the large scale structure we observe in the Universe today. The main constraints on come from observational bounds on the amount of gravitational background radiation emitted by cosmic string loops ( [4 6] and references therein) A loop of cosmic string is formed when two sections of a long string (a string with length greater than the horizon length) meet and intercommute. Once formed, loops begin to oscillate under their own tension, undergoing a process of self intersection (fragmentation) and ....

E. P. S. Shellard and A. Vilenkin, Cosmic Strings and other Topological Defects, (Cambridge University Press, Cambridge, England, 1994).

....radiation emitted by a cosmologically evolving network of massive strings. PACS: 98.80.Cq IHES P 98 06 gr qc 9801105 Typeset using REVT E X I. INTRODUCTION Cosmic strings are predicted, within a wide class of elementary particle models, to form at phase transitions in the early universe [1] [2]. The creation of a network of cosmic strings can have important astrophysical consequence, notably for the formation of structure in the universe [3] 4] A network of cosmic strings might also be a copious source of the various fields or quanta to which they are coupled. Oscillating loops of ....

.... associated to this symmetry breaking will be the dominant radiation damping mechanism and will be characterized by the dimensionless parameter f 2 a = effective (log(L=ffi) Gamma1 10 Gamma2 , where the effective tension effective is renormalized by a large logarithm (see, e.g. [2]) Present numerical simulations of string networks do not take into account the effect of radiative damping on the actual string motion. The above mentioned argument concluding in the case of GUT strings to the link b ff Gamma kink G between the loop size and radiative effects has been ....

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and other Topological Defects, Cambridge University Press, Cambridge, 1994.

....We compare and contrast these results with the literature. PACS numbers: 04.70. b, 11.27. d, 98.80.Cq gr qc 9709029 Typeset using REVT E X I. INTRODUCTION Cosmologists have been attracted to topological defects as a possible source for the density perturbations which seeded galaxy formation [1]. Phase transitions in the early universe can give rise to various types of defect. Briefly, a defect is a discontinuity in the vacuum, and can be classified according to the topology of the vacuum manifold of the field theory model being used. Disconnected vacuum manifolds give domain walls, ....

A.Vilenkin and E.P.S.Shellard, Cosmic strings and other Topological Defects (Cambridge Univ. Press, Cambridge, 1994). R.H.Brandenberger, Modern Cosmology and Structure Formation astro-ph/9411049.

....charged dilatonic black hole is studied in the low velocity limit. In particular, the string black hole scattering at a low velocity is investigated. PACS number(s) 04.40.Nr, 04.70.Bw, 11.27. d Typeset using REVT E X e mail: g00345 sinet.ad.jp, shiraish air.akita u. ac.jp Cosmic strings [1] are topological defects, which may have resulted from a certain phase transition in the early universe. When we take the infinitely thin limit of the string core, the cosmic string is characterized by a single dimensionless number G , where is the mass density per unit length (in the unit c = ....

....spacetime ds 2 = Gammadt 2 dr 2 r 2 d# 2 dz 2 ; 3) but there is a deficit in the azimuthal angle since # has the range 0 # 2 : 4) Then the space has a conical singularity along z axis in the infinitely thin limit of the string. The deficit angle Delta is defined as [1,2] Delta j 2 1 Gamma 1 = 8 G : 5) Linet [3] and Smith [4] have shown that a charged test particle placed near an infinite straight cosmic string feels a static self force caused by the conical structure of the spacetime. It is also interesting to examine how the conical structure ....

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A. Vilenkin and E. P. S. Shellard, Cosmic Strings and other Topological Defects (Cambridge University Press, 1994).

....would have been produced when the universe was 10 Gamma34 sec old and had a temperature of T 10 14 Gamma16 GeV . The gravitational field of such strings may seed structure and, in fact, a network of these strings is an alternative to inflation for the generation of the universe structure [3, 4, 5, 6]. There are two types of gravitational quantum effects associated to cosmic strings (or to any other topological defect) which result from the interaction of the string s gravitational field with any quantum field (i.e. matter) present, namely, particle creation and vacuum polarization. When a ....

A. Vilenkin and E.P.S. Shellard, Cosmic strings and other topological defects (Cambridge University Press, 1994).

.... by populations of collisionless particles like gravitons [6] photons [7] or relativistic neutrinos [8] 9] long wavelength gravitational waves [10] 11] Yang Mills fields [12] axion fields in low energy string theory [13] 14] and topological defects like cosmic strings and domain walls [15] [17] Our experience with high energy physics theories also alerts us to the possibility that a (more) final theory of high energy physics will contain many other matter fields, some of which may well exert anisotropic stresses in the universe. Cosmological observations of the isotropy of the ....

....fall into the category of stress modelled by (12) for part of their evolution. The energy momentum tensors of string sources were also considered more generally by Stachel [16] Marder and Israel [17] The specific description of line stresses created by topological defects is reviewed in ref. [15]. An infinite string with mass per unit length extending in the x direction contributes an anisotropic stress tensor s b a = ffi(z)ffi(y)diag(1; 1; 0; 0) that is = Gamma1; 0 Delta(string) Gamma1: 58) Their evolution could therefore only be critical in a universe containing a ....

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A. Vilenkin and P. Shellard, Cosmic Strings and Other Topological Defects, Cambridge UP, Cambridge, (1994).

....primordial vacuum, an example of which is the cosmic string. A string approach is an appealing one since it can be used to address both questions: the wake left by strings moving through the Universe can produce fluctuations which may lead to the accretion of matter into large scale structures[2][3], whilst their interaction with particles and the decay of string loops can provide mechanisms leading to baryon number violation[4] and the observed matter bias[5] Hence, it is important to understand how these strings form, both to predict how many we can expect to have been created and how ....

A.Vilenkin and E.P.S.Shellard, `Cosmic Strings and Other Topological Defects', CUP, Cambridge, (1994).

....a non existent object With sufficiently good observations, such as a CMB satellite will provide, the answer should be no. The C l spectrum, when it is observed, will contain huge amounts of degenerate information. If the correct underlying theory is topological defects, see for example Vilenkin and Shellard, 1994), the spectral shape should be very different to any simple inflation model for any values of the cosmological parameters. One can certainly reconstruct a potential which would give the observed C l , but it would probably be of such a complex form as to have little particle physics motivation ....

Vilenkin, A. and Shellard, E. P. S., 1994, Cosmic Strings and other topological defects (Cambridge University Press).

.... by populations of collisionless particles like gravitons [6] photons [7] or relativistic neutrinos [8] 9] long wavelength gravitational waves [10] 11] Yang Mills fields [12] axion fields in low energy string theory [13] 14] and topological defects like cosmic strings and domain walls [15] [17] Our experience with high energy physics theories also alerts us to the possibility that a (more) final theory of high energy physics will contain many other matter fields, some of which may well exert anisotropic stresses in the universe. Cosmological observations of the isotropy of the ....

....fall into the category of stress modelled by (12) for part of their evolution. The energy momentum tensors of string sources were also considered more generally by Stachel [16] Marder and Israel [17] The specific description of line stresses created by topological defects is reviewed in ref. [15]. An infinite string with mass per unit length extending in the x direction contributes an anisotropic stress tensor s b a = ffi(z)ffi(y)diag(1; 1; 0; 0) that is = Gamma1; 0 Delta(string) Gamma1: 58) Their evolution could therefore only be critical in a universe containing a ....

[Article contains additional citation context not shown here]

A. Vilenkin and P. Shellard, Cosmic Strings and Other Topological Defects, Cambridge UP, Cambridge, (1994).

....is made with the corresponding results predicted by General Relativity. PACS numbers: 1127, 0450, 9880C 1 Electronic address: cromero dfjp.ufpb.br Monopoles resulting from the breaking of global O(3) symmetry lie among those strange and exotic objects like cosmic strings and domain walls [1], generally referred to as topological defects of space time, which may have existed due to phase transitions in the early universe. Likewise cosmic strings, the most studied of these structures, the gravitational field of a monopole exhibits some interesting properties, particularly those ....

A. Vilenkin and E.P.S. Shellard, Cosmic Strings and other Topological Defects (Cambridge University Press, Cambridge, 1994).

.... R symmetry requires gauged supersymmetry [8] Recently, such gauged U(1)R models have been constructed for phenomenological purposes [9,10] The U(1)R must be spontaneously broken for consistency and as is well known, the breaking of a U(1) symmetry gives rise to cosmic string configurations [11]. What is interesting about gauged R symmetry is that the gravitino must necessarily carry a non zero R charge. This then allows for the possibility that gravitino zero modes may form on the string. This is what we investigate in this work. Fermion zero modes in topologically non trivial ....

....universe depending on when they form. If the R symmetry has to be broken at a scale greater than 10 16 GeV, as may be required from considerations of naturalness [9,10] the energy density in strings may be to large to be accomodated by observations and the strings may have to be inflated away [11]. If use is to be made of gravitino zero modes, the symmetry breaking scale will have to be reduced without fine tuning the theory. It remains to be seen whether such models exist. V. ACKNOWLEDGEMENTS R.H. would like to thank H. Dreiner for stimulating conversations. The authors would also like ....

A. Vilenkin and E.P.S. Shellard, "Cosmic Strings and other Topological Defects", Cambridge University Press (1994).

....generalisation of the Ginzburg Landau model, known as the Abelian Higgs model. Relativistic vortices may be interpreted as a solitonic version of fundamental strings [5] or as strings joining confined quarks, or as cosmic strings produced at a phase transition early in the universe s history [6]. The second possibility is that the vortex velocity is proportional to the force. This is modelled by dissipative equations involving the first time derivatives of the fields [7] Recently, one version of such equations, the Ginzburg Landau gradient flow equations, have been analysed in detail ....

A. VILENKIN AND E.P.S. SHELLARD, "Cosmic Strings and other Topological Defects", Cambridge U.P., Cambridge, 1994.

....have tremendous implications for cosmology mainly through their gravitational interactions with matter. For a nice summary of the subject of TDs, their formation, evolution and their (mainly gravitational) implications for cosmology in general, see the recent monograph by Vilenkin and Shellard[11]. In this talk I will not deal much with those well known gravitational implications of TDs, but will rather concentrate on some nongravitational implications of TDs; in particular, I shall discuss the possibility that TDs, under certain circumstances, may be sources of extremely energetic ....

....may be the sources of the observed highestenergy cosmic rays. Unless otherwise stated, I use natural units with h = c = kB = 1, where kB denotes the Boltzmann constant. I should emphasize that this talk is not intended to be an exhaustive review of the subject of TDs for this purpose, see Ref. [11]. 2 Topological defects and their classification 2.1 Spontaneous Symmetry Breaking (SSB) and Topological Defects (TDs) 2.1.1 Domain Wall Consider the theory of a single scalar field OE described by the Lagrangian density L = 1 2 ( OE) OE) Gamma V (OE) 1) where the potential V ....

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge Univ. Press, Cambridge, 1994).

....a phase transition in the early universe. Strings which have a mass per unit length, such that G 10 Gamma6 , where G is Newton s constant, may play a significant role in the formation of the large scale structures observed in the Universe today. See the monograph by Vilenkin Shellard [1] for a comprehensive review of the physics of cosmic strings. Cosmic strings may display a number of other observable features through which the one free parameter of the cosmic string scenario, may be constrained. The nucleosynthesis limit on relativistic particle species, and the pulsar ....

....Angular Momentum A rotating loop which collapses to form a black hole will produce a rotating black hole. In order that the curvature singularity within the newly formed rotating black hole of mass M lies within the event horizon, the black hole angular momentum JBH must satisfy the inequality [1,10] jJ BH j GM 2 : 2.5) Hence, the angular momentum of the loop which collapses to form a black hole must also satisfy this inequality. For a particular loop configuration, this bound may be expressed as G L Gamma2 Z L 0 doe x(oe; Theta x(oe; 2.6) A cosmic string loop will ....

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A. Vilenkin and E. P. S. Shellard, Cosmic Strings and other Topological Defects, (Cambridge University Press, Cambridge, England, 1994).

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Vilenkin, A. and Shellard, E.P.S., 1994, Cosmic Strings and Other Topological Defects, Cambridge University Press, Cambridge.

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A. Vilenkin and E.P.S. Shellard, `Cosmic Strings and other Topological Defects' (Cambridge Univ. Press, Cambridge, 1994).

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge University Press, Cambridge, 1994).

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge University Press, Cambridge, 1994).

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A. Vilenkin and E. P. S. Shellard, Cosmic strings and other Topological Defects, Cambridge University Press 1994.

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge University Press, Cambridge, 1994).

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A. Vilenkin and E. P. S. Shellard 1994, Cosmic Strings and Other Topological Defects, Cambridge U. Press, Cambridge.

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge University Press, Cambridge, 1994)

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A. Vilenkin and E.P.S. Shellard, Cosmic Strings and Other Topological Defects, Cambridge University Press, Cambridge (1994).

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A. Vilenkin and E. P. S. Shellard, Cosmic Strings and Other Topological Defects (Cambridge Univ. Press, 1994).

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