Article
Physics, Particles & Fields
Arthur Hebecker, Simon Schreyer, Gerben Venken
Summary: There has been recent interest in the possibility of accelerated cosmological expansion in the asymptotic regions of a d-dimensional EFT. It is conjectured that such acceleration is only possible if there are metastable de Sitter vacua in more than d dimensions. This result is in line with Swampland bounds on the potential in the field space asymptotics. Additionally, it is found that the Kaluza-Klein scale always falls below the Hubble scale in these asymptotic decompactification limits.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Per Berglund, Tristan Hubsch, Djordje Minic
Summary: The search for four-dimensional de Sitter spacetime solutions in string theory has been challenging, but recent analysis suggests a connection with bubble-nucleation theory and stringy cosmic brane construction.
Article
Physics, Multidisciplinary
Anxo Biasi, Oleg Evnin, Spyros Sypsas
Summary: Cosmological acceleration is difficult to explain in theories involving supergravity and superstrings, but it is possible in theories with regular black holes. By placing this scenario in a global antide Sitter background, the formation of de Sitter bubbles can be enhanced, potentially leading to the creation of multiple accelerating universes. Numerical work in a two-dimensional dilaton-gravity model supports this idea.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
Tanmay Vachaspati
Summary: This article investigates quantum fields in time-dependent backgrounds and discovers certain backgrounds where particle production is zero. By studying the simple harmonic oscillator, the authors explicitly construct all unexciting time-dependent frequencies and create corresponding homogeneous backgrounds. However, there are no homogeneous backgrounds where particle production vanishes in every mode.
Article
Astronomy & Astrophysics
Min-Seok Seo
Summary: This paper discusses the influence of quantum fluctuations and density fluctuations on black hole production in inflation. It proposes the equivalence between the no eternal inflation condition and the condition that radiation density fluctuations are not sufficient to produce black holes. It also highlights that the information paradox does not arise when the radiation emitted by the horizon does not produce black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Orfeu Bertolami, Paulo M. Sa
Summary: Multi-field cold inflation models are usually at odds with the swampland conjectures in string theory, but can be reconciled in the strong dissipative regime of warm inflation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Mathematical
M. Heydarzadeh
Summary: This paper demonstrates that a power law asymptotic de Sitter inflation can be established for all values of Hankel indices ν related to different background spacetimes, possibly occurring after exponential pure de Sitter inflation. In the proposed model, the universe can always be in the accelerating expansion phase.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Md Sabir Ali, Sourav Bhattacharya
Summary: We study the vacuum polarization effects of the Dirac fermionic field induced by a pointlike global monopole located in the cosmological de Sitter spacetime. By deriving the four orthornormal Dirac modes in this background and quantizing the field using these modes, we compute the fermionic condensate and the vacuum expectation value of the energy-momentum tensor for a massive Dirac field, and investigate numerically their variations with respect to relevant parameters.
Article
Astronomy & Astrophysics
Omer Guleryuz
Summary: In this work, an effective field theory for string inflation with spontaneously broken supersymmetry is presented, without generating any supersymmetric anti-de Sitter vacua. The analysis of nilpotent superfields effectively captures the physics of anti-D3 branes and reveals a novel uplifting method by adding the same parameter as a complex contribution parallel to the decomposition of a superfield. With almost vanishing cosmological constant in the region where the inflationary attractors unify, the introduction of nilpotent superfields drastically extends the string landscape for the de Sitter (swampland) conjecture.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Multidisciplinary
Hao Geng
Summary: In this study of holographic entanglement and information scrambling in de-Sitter space within the context of the DS/dS correspondence, it was found that non-local entanglement structures of dS vacua can extend beyond time-reflection symmetric slices. Additionally, the research extended the geometry to a two-sided configuration and observed interesting phenomena such as the saturation of fast scrambler bound by Sekino and Susskind and the traversability of a wormhole due to a shock wave in the bulk. The study also explored the behavior of two-sided out-of-time-ordered correlator (OTOC) in the late time regime, finding an exponential growth that saturates the chaos bound proposed by Maldacena, Shenker and Stanford, and provided an explanation for these results based on the non-local entanglement structure, ultimately aligning with the ER=EPR proposal.
Article
Physics, Particles & Fields
Erez Y. Urbach
Summary: In this study, we investigate the 'string star' saddle, also known as the Horowitz-Polchinski solution, in d + 1 dimensional thermal AdS space. We find that there is a temperature range in which the saddle resembles the flat space solution discovered by Horowitz and Polchinski. We also examine the connection between this saddle and the small AdS black hole saddle at lower temperatures. Additionally, we analyze how the solutions are affected by the AdS geometry at higher temperatures and identify the leading correction to the Hagedorn temperature. Finally, we explore the thermodynamic instabilities of the solution and propose a Gregory-Laflamme-like instability in the presence of extra dimensions at the AdS curvature scale.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Sujay K. Ashok, Jan Troost
Summary: This study focuses on finite temperature string scale AdS(3) backgrounds, examining the properties and algebraic relationships of backgrounds like AdS(3) x S-1 x T-2 and AdS(3) x S(1) in string theory. The research also verifies the characteristic properties and density of states of the system under different conditions.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Sujay K. Ashok, Jan Troost
Summary: The study revisited the calculation of the thermal free energy in three-dimensional anti-de Sitter spacetime with Neveu-Schwarz-Neveu-Schwarz flux and extended it to superstrings. The boundary toroidal twisted partition function in the Ramond-Ramond sector was calculated and lower bounds on the boundary conformal dimension were proven from the bulk perspective. The study also classified Ramond-Ramond ground states and constructed their second quantized partition function, revealing intriguing modular properties.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ugur Atli, Omer Guleryuz
Summary: This study introduces a bounded de Sitter conjecture for single-field slow-roll inflation theory, incorporating the concepts of supergravity methods, Kahler kinetic terms, and single-field slow-roll inflation parameters.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Particles & Fields
Carmen A. Nunez, Facundo Emanuel Rost
Summary: The alpha ' -complete cosmology developed by Hohm and Zwiebach categorizes O(d, d; ) invariant theories and explores the construction and properties of non-perturbative de Sitter solutions within this theoretical framework.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Fien Apers, Miguel Montero, Thomas Van Riet, Timm Wrase
Summary: This study investigates the flux compactifications of massive IIA supergravity with O6 planes, examining the properties of AdS(3) and AdS(4) vacua and the potential dual CFT(2) and CFT(3) theories. Results show stability of AdS(3) vacua and the absence of integer dimensions for operators in the putative CFT2 dual theories.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Jacob Bardzell, Eduardo Gonzalo, Muthusamy Rajaguru, Danielle Smith, Timm Wrase
Summary: This article revisits flux compactifications of type IIB string theory on rigid Calabi-Yau manifolds. This relatively unexplored part of the string landscape contains many interesting four-dimensional solutions, and discusses how these solutions fit into the swampland conjectures.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
David Andriot, Ludwig Horer, Paul Marconnet
Summary: In this paper, we classify and study certain supergravity solutions with different spacetime properties. Using new numerical tools, we discover previously unexplored solutions and analyze their properties and stability. We propose a new conjecture regarding the existence of a flat direction.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
David Andriot, Ludwig Horer, Paul Marconnet
Summary: This paper classifies solutions of 10-dimensional type IIA/B supergravity theories with orientifolds on a 4-dimensional maximally symmetric spacetime multiplied by a 6-dimensional group manifold. It explores previously unexplored solution classes and discovers new solutions including (anti-) de Sitter solutions with intersecting O-4, O-6 and O-6, and Minkowski solutions with 3 intersecting O-5. The paper also presents new no-go theorems against (anti-) de Sitter solutions and conjectures the absence of de Sitter solutions for 2 or less intersecting source sets, indicating that a 4-dimensional effective theory with de Sitter solutions is at most N = 1 supersymmetric.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Correction
Physics, Particles & Fields
David Andriot, Ludwig Horer, Paul Marconnet
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Renata Kanosh, Andrei Linde, Timm Wrase, Yusuke Yamada
Summary: This article discusses the tachyonic instabilities caused by goldstino condensation in the Volkov-Akulov (VA) model, related supergravity models, and the KKLT model in string theory. The authors of [1] constructed a specific model with two unconstrained interacting chiral superfields that have linearly realized supersymmetry and an unstable vacuum state. However, it is shown that the UV limit of their model is discontinuous and the vacuum instability proposed in [1] is not relevant to the VA model, related supergravity models, and the KKLT construction.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
David Andriot, Ludwig Horer
Summary: In this work, the existence of string theory solutions with a d-dimensional (quasi-) de Sitter spacetime, for 3 <= d <= 10, is investigated. No-go theorems valid for general d are derived through classical compactifications. These theorems are used to exclude (quasi-) de Sitter solutions for d >= 7, and it is found unlikely for d = 6, 5 as well. Parameter c of the swampland de Sitter conjecture, M-p |del V |/V >= c, is computed for each no-go theorem. The TCC bound c >= 2/root(d-1)(d-2) is perfectly satisfied for d >= 4, but violated in d = 3. Related proposals in the literature, including the swampland distance conjecture, decay rate, and accelerated expansion bound, are also discussed.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
David Andriot, Paul Marconnet, Muthusamy Rajaguru, Timm Wrase
Summary: Classical flux compactifications are an important research field in string theory, providing a testing ground for various conjectures. This paper focuses on type II supergravity compactifications on 6d group manifolds towards 4d maximally symmetric spacetimes, and develops a code for automated calculations and analysis.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Katrin Becker, Eduardo Gonzalo, Johannes Walcher, Timm Wrase
Summary: This article investigates Type IIB flux vacua based on Landau-Ginzburg models, providing insights into non-geometric and strongly-coupled string landscapes. By studying supersymmetric flux configurations, it is found that there are massless fields that are not all flat directions of the super-potential at higher order. Additionally, new supersymmetric 4d N = 1 Minkowski and AdS vacua are described and compared with other swampland conjectures.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Paul Marconnet, Dimitrios Tsimpis
Summary: We study 4d Friedmann-Lemaitre-Robertson-Walker cosmologies obtained from time-dependent compactifications of Type IIA 10d supergravity on various classes of 6d manifolds (Calabi-Yau, Einstein, Einstein-Kahler). The cosmologies we present are universal in that they do not depend on the detailed features of the compactification manifold, but only on the properties which are common to all the manifolds belonging to that class. Once the equations of motion are rewritten as an appropriate dynamical system, the existence of solutions featuring a phase of accelerated expansion is made manifest. The fixed points of this dynamical system, as well as the trajectories on the boundary of the phase space, correspond to analytic solutions which we determine explicitly. Furthermore, some of the resulting cosmologies exhibit eternal or semi-eternal acceleration, whereas others allow for a parametric control on the number of e-foldings. At future infinity, one can achieve both large volume and weak string coupling. Moreover, we find several smooth accelerating cosmologies without Big Bang singularities: the universe is contracting in the cosmological past (T < 0), expanding in the future (T > 0), while in the vicinity of T = 0 it becomes de Sitter in hyperbolic slicing. We also obtain several cosmologies featuring an infinite number of cycles of alternating periods of accelerated and decelerated expansions.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
David Andriot, Ludwig Horer, George Tringas
Summary: In this paper, we characterize negative scalar potentials, V < 0, in d-dimensional effective theories of quantum gravity through the Anti-Trans-Planckian Censorship Conjecture (ATCC) inspired by a refined version of the TCC. The ATCC is based on the fact that sub-Planckian length modes violate the validity of the effective theory in a contracting universe. In the asymptotics of field space, we find that -V'/V >= c(0) when V' >= 0. We also derive a new asymptotic condition, V''/V >= c(0)(2), and infer the existence of a scalar with mass satisfying m(2)l(2) less than or similar to -2 in anti-de Sitter solutions.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nelson R. F. Braga, Octavio C. Junqueira
Summary: This study investigates the influence of rotation on the transition temperature of strongly interacting matter produced in non-central heavy ion collisions. By using a holographic description of an AdS black hole, the authors extend the analysis to the more realistic case where the matter spreads over a region around the rotational axis. The results show the coexistence of confined and deconfined phases and are consistent with the concept of local temperature in rotating frames developed by Tolman and Ehrenfest.
Article
Astronomy & Astrophysics
Bing Sun, Jiachen An, Zhoujian Cao
Summary: This paper investigates the effect of gravitational constant variation on the propagation of gravitational waves. By employing two analytical methods, the study finds that variations in the gravitational constant result in amplitude and phase corrections for gravitational waves, and the time variation of the gravitational constant can be constrained through the propagation of gravitational waves.
Article
Astronomy & Astrophysics
Abdellah Touati, Zaim Slimane
Summary: This letter presents the first study of Hawking radiation as a tunneling process within the framework of non-commutative gauge theory of gravity. The non-commutative Schwarzschild black hole is reconstructed using the Seiberg-Witten map and the star product. The emission spectrum of outgoing massless particles is computed using the quantum tunneling mechanism. The results reveal pure thermal radiation in the low-frequency scenario, but a deviation from pure thermal radiation in the high-frequency scenario due to energy conservation. It is also found that noncommutativity enhances the correlations between successively emitted particles.
Article
Astronomy & Astrophysics
Shahar Hod
Summary: The travel times of light signals between two antipodal points on a compact star's surface are calculated for two different trajectories. It is shown that, for highly dense stars, the longer trajectory along the surface may have a shorter travel time as measured by asymptotic observers. A critical value of the dimensionless density-area parameter is determined for constant density stars to distinguish cases where crossing through the star's center or following a semi-circular trajectory on the surface has a shorter travel time as measured by asymptotic observers.
