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Tracker and scaling solutions in DHOST theories

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Tracker and scaling solutions in DHOST theories. / Frusciante, Noemi; Kase, Ryotaro; Koyama, Kazuya; Tsujikawa, Shinji; Vernieri, Daniele.

In: Physical Letters B, 08.01.2019.

Research output: Contribution to journalArticle

Harvard

Frusciante, N, Kase, R, Koyama, K, Tsujikawa, S & Vernieri, D 2019, 'Tracker and scaling solutions in DHOST theories' Physical Letters B.

APA

Frusciante, N., Kase, R., Koyama, K., Tsujikawa, S., & Vernieri, D. (Accepted/In press). Tracker and scaling solutions in DHOST theories. Physical Letters B.

Vancouver

Frusciante N, Kase R, Koyama K, Tsujikawa S, Vernieri D. Tracker and scaling solutions in DHOST theories. Physical Letters B. 2019 Jan 8.

Author

Frusciante, Noemi ; Kase, Ryotaro ; Koyama, Kazuya ; Tsujikawa, Shinji ; Vernieri, Daniele. / Tracker and scaling solutions in DHOST theories. In: Physical Letters B. 2019.

Bibtex

@article{11b57767cad84b1d87007e9b7f6d2a2d,
title = "Tracker and scaling solutions in DHOST theories",
abstract = "In quartic-order degenerate higher-order scalar-tensor (DHOST) theories compatible with gravitational-wave constraints, we derive the most general Lagrangian allowing for tracker solutions characterized by φ˙/Hp=constant, where φ˙ is the time derivative of a scalar field φ, H is the Hubble expansion rate, and p is a constant. While the tracker is present up to the cubic-order Horndeski Lagrangian L=c2X−c3X(p−1)/(2p)□φ, where c2,c3 are constants and X is the kinetic energy of φ, the DHOST interaction breaks this structure for p≠1. Even in the latter case, however, there exists an approximate tracker solution in the early cosmological epoch with the nearly constant field equation of state wφ=−1−2pH˙/(3H2). The scaling solution, which corresponds to p=1, is the unique case in which all the terms in the field density ρφ and the pressure Pφ obey the scaling relation ρφ∝Pφ∝H2. Extending the analysis to the coupled DHOST theories with the field-dependent coupling Q(φ) between the scalar field and matter, we show that the scaling solution exists for Q(φ)=1/(μ1φ+μ2), where μ1 and μ2 are constants. For the constant Q, i.e., μ1=0, we derive fixed points of the dynamical system by using the general Lagrangian with scaling solutions. This result can be applied to the model construction of late-time cosmic acceleration preceded by the scaling φ-matter-dominated epoch.",
keywords = "gr-qc, astro-ph.CO, hep-ph, hep-th, RCUK, STFC, ST/N000668/1",
author = "Noemi Frusciante and Ryotaro Kase and Kazuya Koyama and Shinji Tsujikawa and Daniele Vernieri",
note = "11 pages",
year = "2019",
month = "1",
day = "8",
language = "English",
journal = "Physical Letters B",
issn = "0370-2693",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Tracker and scaling solutions in DHOST theories

AU - Frusciante, Noemi

AU - Kase, Ryotaro

AU - Koyama, Kazuya

AU - Tsujikawa, Shinji

AU - Vernieri, Daniele

N1 - 11 pages

PY - 2019/1/8

Y1 - 2019/1/8

N2 - In quartic-order degenerate higher-order scalar-tensor (DHOST) theories compatible with gravitational-wave constraints, we derive the most general Lagrangian allowing for tracker solutions characterized by φ˙/Hp=constant, where φ˙ is the time derivative of a scalar field φ, H is the Hubble expansion rate, and p is a constant. While the tracker is present up to the cubic-order Horndeski Lagrangian L=c2X−c3X(p−1)/(2p)□φ, where c2,c3 are constants and X is the kinetic energy of φ, the DHOST interaction breaks this structure for p≠1. Even in the latter case, however, there exists an approximate tracker solution in the early cosmological epoch with the nearly constant field equation of state wφ=−1−2pH˙/(3H2). The scaling solution, which corresponds to p=1, is the unique case in which all the terms in the field density ρφ and the pressure Pφ obey the scaling relation ρφ∝Pφ∝H2. Extending the analysis to the coupled DHOST theories with the field-dependent coupling Q(φ) between the scalar field and matter, we show that the scaling solution exists for Q(φ)=1/(μ1φ+μ2), where μ1 and μ2 are constants. For the constant Q, i.e., μ1=0, we derive fixed points of the dynamical system by using the general Lagrangian with scaling solutions. This result can be applied to the model construction of late-time cosmic acceleration preceded by the scaling φ-matter-dominated epoch.

AB - In quartic-order degenerate higher-order scalar-tensor (DHOST) theories compatible with gravitational-wave constraints, we derive the most general Lagrangian allowing for tracker solutions characterized by φ˙/Hp=constant, where φ˙ is the time derivative of a scalar field φ, H is the Hubble expansion rate, and p is a constant. While the tracker is present up to the cubic-order Horndeski Lagrangian L=c2X−c3X(p−1)/(2p)□φ, where c2,c3 are constants and X is the kinetic energy of φ, the DHOST interaction breaks this structure for p≠1. Even in the latter case, however, there exists an approximate tracker solution in the early cosmological epoch with the nearly constant field equation of state wφ=−1−2pH˙/(3H2). The scaling solution, which corresponds to p=1, is the unique case in which all the terms in the field density ρφ and the pressure Pφ obey the scaling relation ρφ∝Pφ∝H2. Extending the analysis to the coupled DHOST theories with the field-dependent coupling Q(φ) between the scalar field and matter, we show that the scaling solution exists for Q(φ)=1/(μ1φ+μ2), where μ1 and μ2 are constants. For the constant Q, i.e., μ1=0, we derive fixed points of the dynamical system by using the general Lagrangian with scaling solutions. This result can be applied to the model construction of late-time cosmic acceleration preceded by the scaling φ-matter-dominated epoch.

KW - gr-qc

KW - astro-ph.CO

KW - hep-ph

KW - hep-th

KW - RCUK

KW - STFC

KW - ST/N000668/1

M3 - Article

JO - Physical Letters B

T2 - Physical Letters B

JF - Physical Letters B

SN - 0370-2693

ER -

ID: 12718662