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Author  |
Baeza-Ballesteros, J.; Copeland, E.J.; Figueroa, D.G.; Lizarraga, J. |
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Title |
Gravitational wave emission from a cosmic string loop: Global case |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
110 |
Issue |
4 |
Pages |
043522 - 12pp |
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Abstract |
We study the simultaneous decay of global string loops into scalar particles (massless and massive modes) and gravitational waves (GWs). Using field-theory simulations in flat space-time of isolated loops with initial length similar to 80-1700 times their core width, we determine the power emitted into scalar particles, P phi , and GWs, P GW , and characterize the loop-decay timescale as a function of its initial length, energy, and angular momentum. We quantify infrared and ultraviolet lattice dependencies of our results. For all type of loops and initial conditions considered, GW emission is always suppressed compared to particles as P GW /P phi approximate to O(10)(v/mp)2 ( 10 )( v/m p ) 2 << 1, where v is the vacuum expectation value associated with string formation. These conclusions are robust for the length-to-width ratios considered, with no indication they should change if the ratio is increased. The results suggest that the GW background from a global string network, such as in dark-matter axion scenarios, will be suppressed compared to previous expectations. |
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Address |
[Baeza-Ballesteros, Jorge; Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, Valencia 46980, Spain, Email: jorge.baeza@ific.uv.es; |
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Publisher |
Amer Physical Soc |
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English |
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Series Volume |
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Edition |
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ISSN |
2470-0010 |
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Expedition |
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Conference |
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Notes |
WOS:001381346400003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6390 |
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Author |
Figueroa, D.G.; Hindmarsh, M.; Lizarraga, J.; Urrestilla, J. |
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Title |
Irreducible background of gravitational waves from a cosmic defect network: Update and comparison of numerical techniques |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
102 |
Issue |
10 |
Pages |
103516 - 25pp |
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Keywords |
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Abstract |
Cosmological phase transitions in the early Universe may produce relics in the form of a network of cosmic defects. Independently of the order of a phase transition, topology of the defects, and their global or gauge nature, the defects are expected to emit gravitational waves (GWs) as the network energy-momentum tensor adapts itself to maintaining scaling. We show that the evolution of any defect network (and for that matter any scaling source) emits a GW background with spectrum Omega(GW) proportional to f(3) for f << f(0), Omega(GW) proportional to 1/f(2) for f(0) less than or similar to f less than or similar to feq, and Omega(GW) proportional to const (i.e., exactly scale invariant) for f >> f(eq), where f(0) and f(eq) denote respectively the frequencies corresponding to the present and matter-radiation equality horizons. This background represents an irreducible emission of GWs from any scaling network of cosmic defects, with its amplitude characterized only by the symmetry-breaking scale and the nature of the defects. Using classical lattice simulations we calculate the GW signal emitted by defects created after the breaking of a global symmetry O(N) -> O(N – 1). We obtain the GW spectrum for N between 2 and 20 with two different techniques: integrating over unequal-time correlators of the energy-momentum tensor, updating our previous work on smaller lattices, and for the first time, comparing the result with the real-time evolution of the tensor perturbations sourced by the same defects. Our results validate the equivalence of the two techniques. Using cosmic microwave background upper bounds on the defects' energy scale, we discuss the difficulty of detecting this GW background in the case of global defects. |
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Address |
[Figueroa, Daniel G.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46980 Valencia, Spain, Email: daniel.figueroa@ific.uv.es; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2470-0010 |
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Expedition |
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Conference |
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Notes |
WOS:000589181600006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4618 |
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Author |
Figueroa, D.G.; Lizarraga, J.; Urio, A.; Urrestilla, J. |
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Title |
Strong Backreaction Regime in Axion Inflation |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
131 |
Issue |
15 |
Pages |
151003 - 7pp |
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Keywords |
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Abstract |
We study the nonlinear dynamics of axion inflation, capturing for the first time the inhomogeneity and full dynamical range during strong backreaction, till the end of inflation. Accounting for inhomogeneous effects leads to a number of new relevant results, compared to spatially homogeneous studies: (i) the number of extra efoldings beyond slow-roll inflation increases very rapidly with the coupling, (ii) oscillations of the inflaton velocity are attenuated, (iii) the tachyonic gauge field helicity spectrum is smoothed out (i.e., the spectral oscillatory features disappear), broadened, and shifted to smaller scales, and (iv) the nontachyonic helicity is excited, reducing the chiral asymmetry, now scale dependent. Our results are expected to impact strongly on the phenomenology and observability of axion inflation, including gravitational wave generation and primordial black hole production. |
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Address |
[Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, Valencia 46980, Spain, Email: daniel.figueroa@ific.uv.es; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-9007 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001093422100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5783 |
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