Questions tagged [cosmic-string]

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Gravitational lensing and cosmic strings

Say we have a straight cosmic string lying along the $z$-axis, with energy-momentum tensor $$T_{\mu\nu}=\mu\delta(x)\delta(y)\operatorname{diag}(1,0,0,-1)\tag{1}\label{1}$$ for some small positive ...
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Candidates for cosmic strings

What are the observed candidates for cosmic strings (or other defects), that are not ruled out? With references if possible.
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0answers
68 views

Basic question on Cosmic Strings

What is the typical size of Cosmic String Loops? If a loop is formed today, what are the restrictions on its size? I would like to know if there is a distribution of cosmic strings depending on its ...
2
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1answer
144 views

Kalb-Ramond action and topological string radiation

Let's have simple scalar $\Phi$ action involves spontaneously symmetry breaking in a form $$ \tag 1 S = \int d^{4}x\left( |\partial_{\mu}\psi|^{2} + \psi^{2}|\partial_{\mu}\theta |^{2} - \frac{\lambda}...
2
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1answer
133 views

What's the connection between cosmic strings and the strings hypothesized in string theory?

I read somewhere that Edward Witten, the (once) big hotshot of string theory, said that the discovery of cosmic strings (at the beginning of this Wikipedia article it is written: "Not to be confused ...
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1answer
143 views

What is a String Wall?

This question has nothing to do with sound waves, physical strings or walls... I am reading: https://arxiv.org/abs/1709.07091 It states "In the post-inflationary PQ symmetry breaking scenario, ...
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1answer
84 views

Global cosmic strings evolution

Recently I've read about axion string. It can be shown that the energy per unit length of the string located along $z$ axis is $$ \mu = 2 \pi f_{a}^{2}\ln\left( \frac{L}{\delta}\right), $$ where $L$ ...
1
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1answer
35 views

Cosmic strings and ground state degeneracy in SSB

There are two conflicting perceptions that I have regarding the notion of ground state post-SSB. Consider the Higgs mechanism e.g. for the electroweak theory. On the one hand, we say that the vacuum ...
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0answers
77 views

Black hole and the cosmic string

For a regular black hole, the mass and energy of the black hole are identical(according to first law of black hole thermodynamics), but for a black hole with a cosmic string this is not satisfied. ...
0
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1answer
57 views

I've read a cosmic string can accelerate a mass. Can someone explain how it works?

In the book Brief Answers to the Big Questions: the final book from Stephen Hawking Hawking describes cosmic strings as follows; They are like rubber bands as they are under great tension, ...
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2answers
172 views

Cosmic string & grandfather paradox

Cosmic string was proposed several decades ago and there are claims stating it can span across the length of the universe and is less than an atom thick. How does a broken pieces of these cosmic ...