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Author Figueroa, D.G.; Hindmarsh, M.; Lizarraga, J.; Urrestilla, J. url  doi
openurl 
  Title Irreducible background of gravitational waves from a cosmic defect network: Update and comparison of numerical techniques Type Journal Article
  Year 2020 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 102 Issue 10 Pages 103516 - 25pp  
  Keywords (up)  
  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.  
  Address [Figueroa, Daniel G.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46980 Valencia, Spain, Email: daniel.figueroa@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000589181600006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4618  
Permanent link to this record
 

 
Author Antusch, S.; Figueroa, D.G.; Marschall, K.; Torrenti, F. url  doi
openurl 
  Title Energy distribution and equation of state of the early Universe: Matching the end of inflation and the onset of radiation domination Type Journal Article
  Year 2020 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 811 Issue Pages 135888 - 7pp  
  Keywords (up)  
  Abstract We study the energy distribution and equation of state of the universe between the end of inflation and the onset of radiation domination (RD), considering observationally consistent single-field inflationary scenarios, with a potential 'flattening' at large field values, and a monomial shape V(phi) proportional to vertical bar phi vertical bar(p) around the origin. As a proxy for (p)reheating, we include a quadratic interaction g(2)phi X-2(2) between the inflaton phi and a light scalar 'daughter' field X, with g(2) > 0. We capture the non-perturbative and non-linear nature of the system dynamics with lattice simulations, obtaining that: i) the final energy transferred to X depends only on p, not on g(2); ii) the final transfer of energy is always negligible for 2 <= p < 4, and of order similar to 50% for p >= 4; iii) the system goes at late times to matter-domination for p = 2, and always to RD for p > 2. In the latter case we calculate the number of e-folds until RD, significantly reducing the uncertainty in the inflationary observables Tl-s and r.  
  Address [Antusch, Stefan; Marschall, Kenneth; Torrenti, Francisco] Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland, Email: f.torrenti@unibas.ch  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000612225400040 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4699  
Permanent link to this record
 

 
Author Figueroa, D.G.; Raatikainen, S.; Rasanen, S.; Tomberg, E. url  doi
openurl 
  Title Non-Gaussian Tail of the Curvature Perturbation in Stochastic Ultraslow-Roll Inflation: Implications for Primordial Black Hole Production Type Journal Article
  Year 2021 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 127 Issue 10 Pages 101302 - 7pp  
  Keywords (up)  
  Abstract We consider quantum diffusion in ultraslow-roll (USR) inflation. Using the Delta N formalism, we present the first stochastic calculation of the probability distribution P(R) of the curvature perturbation during USR. We capture the nonlinearity of the system, solving the coupled evolution of the coarse-grained background with random kicks from the short wavelength modes, simultaneously with the mode evolution around the stochastic background. This leads to a non-Markovian process from which we determine the highly non-Gaussian tail of P(R). Studying the production of primordial black holes in a viable model, we find that stochastic effects during USR increase their abundance by a factor of similar to 10(5) compared with the Gaussian approximation.  
  Address [Figueroa, Daniel G.] Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, E-46980 Valencia, Spain  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000692791400004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4952  
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Author Antusch, S.; Figueroa, D.G.; Marschall, K.; Torrenti, F. url  doi
openurl 
  Title Characterizing the postinflationary reheating history: Single daughter field with quadratic-quadratic interaction Type Journal Article
  Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 105 Issue 4 Pages 043532 - 36pp  
  Keywords (up)  
  Abstract We study the evolution of the energy distribution and equation of state of the Universe from the end of inflation until the onset of either radiation domination (RD) or a transient period of matter domination (MD). We use both analytical techniques and lattice simulations. We consider two-field models where the inflaton (/) has a monomial potential after inflation V((/)) proportional to i(/) – vip (p 4, and of order similar to 50% for p 4. The system goes to MD at late times for p = 2, while it goes to RD for p > 2. In the later case, we can calculate exactly the number of e-folds until RD as a function of g2, and hence predict accurately inflationary observables like the scalar tilt ns and the tensor-to-scalar ratio r. In the scenario (ii), the energy is always transferred completely to X for p > 2, as long as its effective mass m2X = g2((/) – v)2 is not negligible. For p = 2, the final ratio between the energy densities of X and (/) depends strongly on g2. For all p > 2, the system always goes to MD at late times.  
  Address [Antusch, Stefan; Marschall, Kenneth; Torrenti, Francisco] Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000767129500008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5173  
Permanent link to this record
 

 
Author Figueroa, D.G.; Florio, A.; Loayza, N.; Pieroni, M. url  doi
openurl 
  Title Spectroscopy of particle couplings with gravitational waves Type Journal Article
  Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 106 Issue 6 Pages 063522 - 8pp  
  Keywords (up)  
  Abstract We discuss the possibility to measure particle couplings with stochastic gravitational wave backgrounds (SGWBs). Under certain circumstances a sequence of peaks of different amplitude and frequency-a stairway-emerges in a SGWB spectrum, with each peak probing a different coupling. The detection of such signature opens the possibility to reconstruct couplings (spectroscopy) of particle species involved in high energy phenomena generating SGWBs. Stairwaylike signatures may arise in causally produced backgrounds in the early Universe, e.g., from preheating or first order phase transitions. As a proof of principle we study a preheating scenario with an inflaton 0 coupled to multiple daughter fields f chi jg with different coupling strengths. As a clear stairway signature is imprinted in the SGWB spectrum, we reconstruct the relevant couplings with various detectors.  
  Address [Figueroa, Daniel G.; Loayza, Nicolas] Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, E-46980 Valencia, Spain  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000861731100002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5367  
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