Article
Astronomy & Astrophysics
Dukjae Jang, Youngshin Kwon, Kyujin Kwak, Myung-Ki Cheoun
Summary: The study proposes a correction to the standard BBN scenario, suggesting that a deviation of the primordial plasma from the ideal state could resolve the primordial lithium problem by deviating from the Planck distribution.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Marcus Hogas, Edvard Mortsell
Summary: Bimetric gravity, as a ghost-free extension of general relativity, provides constraints on the expansion history of the Universe using observed abundances of light elements. Constraints on theory parameters in bimetric gravity, such as the mixing angle between massless and massive gravitons, are complementary to other cosmological probes and show a significant improvement in accuracy.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Eunseok Hwang, Dukjae Jang, Kiwan Park, Motohiko Kusakabe, Toshitaka Kajino, A. Baha Balantekin, Tomoyuki Maruyama, Chang-Mo Ryu, Myung-Ki Cheoun
Summary: In this study, the dynamic screening effects of moving ions on big bang nucleosynthesis were explored, with findings indicating significant suppression of these effects during the BBN epoch due to the low density of background plasma components. The comparison with thermonuclear reaction rates for solar fusion was conducted to analyze the impact of dynamic screening effects, with discussions on potential expansion of the study to other astrophysical scenarios in the future.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Tsung-Han Yeh, Keith A. Olive, Brian D. Fields
Summary: The effect of neutron lifetime and its uncertainty on standard big bang nucleosynthesis (BBN) is explored in this study. It is found that the uncertainties in neutron lifetime dominate the predicted errors in He-4 abundance. However, these theory errors are still smaller than the uncertainties in He-4 observations. For the predictions of other light elements, neutron lifetime contributes negligibly to their error budget.
Article
Astronomy & Astrophysics
Jorge Venzor, Abdel Perez-Lorenzana, Josue De-Santiago
Summary: Coherent forward scattering processes by neutrino-scalar nonstandard interactions induce an effective neutrino mass, limiting neutrino production in the early Universe. The effect is modulated by two effective couplings, G(eff) and G(S), which are related to the effective number of relativistic species. Constraints on these parameters are obtained using big bang nucleosynthesis, with implications for the neutrino-scalar coupling.
Article
Physics, Multidisciplinary
Cara Giovanetti, Mariangela Lisanti, Hongwan Liu, Joshua T. Ruderman
Summary: Dark sectors provide a theoretical framework for studying thermally-produced low-energy dark matter, and these sectors can be constrained by measuring cosmic background radiation and early universe elemental abundances.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
David Langlois, Karim Noui, Hugo Roussille
Summary: A novel and remarkably simple formulation of degenerate higher-order scalar-tensor (DHOST) theories is presented, which can be simplified to the usual Einstein-Hilbert term through disformal transformations. This classification of all quadratic DHOST theories becomes transparent in a geometric reformulation that applies also to scalar-tensor theories degenerate only in the unitary gauge.
Article
Astronomy & Astrophysics
Jubin Park, Chae-min Yun, Myung-Ki Cheoun, Dukjae Jang
Summary: In this study, the cosmic evolutions in the extended Starobinsky model (eSM) are investigated by adding one RabRab term to the Starobinsky model. It is shown that various cosmic evolutions, including the standard cosmic evolution and a unique oscillating cosmic evolution, are feasible in the eSM due to the effects of higher-order terms beyond Einstein's gravity. Furthermore, big bang nucleosynthesis is considered to constrain the free parameters of the eSM, and it is found that most non-standard cosmic evolutions cannot easily satisfy the constraints, but the oscillating cosmic evolution has an upper limit for its free parameter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Erik Jimenez-Vazquez, Miguel Alcubierre
Summary: We study the critical gravitational collapse of a massless scalar field nonminimally coupled to gravity and determine the values of critical amplitude, critical exponent, and echoing exponent. We find that the behavior is similar to that of a minimally coupled scalar field for small coupling, but becomes more violent and rich in high coupling. A special slicing condition is introduced to avoid gauge pathologies in the strong-coupling regime.
Article
Astronomy & Astrophysics
Osamu Seto, Yo Toda
Summary: A cosmological model with a time-varying mass of electrons is considered as a potential solution to the Hubble tension. The big bang nucleosynthesis (BBN) constraints are examined for this model, which shows that a larger electron mass can affect the weak interaction rate and hence the light element abundance. The inferred cosmological parameters, particularly baryon asymmetry, also have an impact on the light element abundance while keeping the cosmic microwave background power spectrum unchanged. It is found that the proton-to-neutron ratio is not very sensitive to the electron mass, but the BBN data suggests a slightly smaller present Hubble parameter and electron mass.
Article
Astronomy & Astrophysics
Tomo Takahashi, Sora Yamashita
Summary: Recent measurements of the primordial 4He abundance Yp from EMPRESS indicate deviations from the standard cosmological model, suggesting a different number of neutrino species and nonzero lepton asymmetry. Taking into account the Hubble tension, the standard ACDM framework may need to be extended, leading to a slightly higher derived baryon density. Alternatively, considering the existence of early dark energy could alleviate the tension implied by the EMPRESS Yp results.
Article
Astronomy & Astrophysics
Cristian Erices, Pantelis Filis, Eleftherios Papantonopoulos
Summary: The study demonstrates the avoidance of the no-hair theorem in scalar-tensor theories with bimetric structure by introducing an electric charge, leading to black hole solutions with rich thermodynamic behavior. The interplay of stability and phase transitions between different black hole configurations resembles a solid-liquid-gas system, with an electric potential acting as pressure and a triple point where three phases coexist equally probable.
Article
Physics, Particles & Fields
Abhay Ashtekar, Tommaso de Lorenzo, Marc Schneider
Summary: A systematic investigation of linear, test quantum fields in cosmological space-times reveals that these fields remain well-defined across the big bang singularity, with specific properties of their expectation values and correlations between fields at spatially and temporally separated points. The renormalized products of fields also remain well-defined, indicating that the big bang (and the big crunch) singularities are harmless when probed with observables associated with quantum fields.
ADVANCES IN THEORETICAL AND MATHEMATICAL PHYSICS
(2021)
Article
Astronomy & Astrophysics
Teodor Borislavov Vasilev, Mariam Bouhmadi-Lopez, Prado Martin-Moruno
Summary: We revise the future fate of kinetic gravity braiding models, a group of scalar-tensor theories. These models can drive the expansion of the universe towards a future de Sitter state if the Lagrangian is invariant under constant shifts in the scalar field. However, we show that future cosmic singularities characterized by a divergence of the energy density can also appear in this framework. We present an explicit example where a big rip singularity is the only possible future fate of the cosmos.
Article
Physics, Multidisciplinary
Petr Jizba, Gaetano Lambiase
Summary: By employing Tsallis' non-additive delta-entropy, this paper formulates the thermodynamic laws for gravitating systems and applies them to cosmology. The results show that Tsallis cosmology can consistently describe the formation of cold dark matter particles and primordial light elements.
Article
Astronomy & Astrophysics
Elisabeth Vangioni, Keith A. Olive, Tanner Prestegard, Joseph Silk, Patrick Petitjean, Vuk Mandic
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2015)
Article
Astronomy & Astrophysics
Emilian Dudas, Yann Mambrini, Keith A. Olive
Article
Physics, Particles & Fields
O. Buchmueller, R. Cavanaugh, A. De Roeck, M. J. Dolan, J. R. Ellis, H. Flaecher, S. Heinemeyer, G. Isidori, J. Marrouche, D. Martinez Santos, K. A. Olive, S. Rogerson, F. J. Ronga, K. J. de Vries, G. Weiglein
EUROPEAN PHYSICAL JOURNAL C
(2014)
Article
Physics, Particles & Fields
Jason L. Evans, Masahiro Ibe, Keith A. Olive, Tsutomu T. Yanagida
EUROPEAN PHYSICAL JOURNAL C
(2014)
Article
Physics, Particles & Fields
Jason L. Evans, Masahiro Ibe, Keith A. Olive, Tsutomu T. Yanagida
EUROPEAN PHYSICAL JOURNAL C
(2014)
Article
Physics, Particles & Fields
John Ellis, Keith A. Olive, Jiaming Zheng
EUROPEAN PHYSICAL JOURNAL C
(2014)
Article
Physics, Particles & Fields
O. Buchmueller, M. J. Dolan, J. Ellis, T. Hahn, S. Heinemeyer, W. Hollik, J. Marrouche, K. A. Olive, H. Rzehak, K. J. de Vries, G. Weiglein
EUROPEAN PHYSICAL JOURNAL C
(2014)
Article
Astronomy & Astrophysics
Erik Aver, Keith A. Olive, R. L. Porter, Evan D. Skillman
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2013)
Article
Astronomy & Astrophysics
John Ellis, Marcos A. G. Garcia, Dimitri V. Nanopoulos, Keith A. Olive
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2014)
Article
Astronomy & Astrophysics
Jason L. Evans, Marcos A. G. Garcia, Keith A. Olive
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2014)
Article
Astronomy & Astrophysics
John Ellis, Marcos A. G. Garcia, Dimitri V. Nanopoulos, Keith A. Olive
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2014)
Article
Astronomy & Astrophysics
Jason L. Evans, Keith A. Olive
Article
Astronomy & Astrophysics
John Ellis, Dimitri V. Nanopoulos, Keith A. Olive
Article
Physics, Particles & Fields
Kunio Kaneta, Natsumi Nagata, Keith A. Olive, Maxim Pospelov, Liliana Velasco-Sevilla
Summary: We revisited the calculation of EDMs in the CMSSM model, where the large mass of the Higgs boson coupled with the lack of discovery of supersymmetric particles at the LHC has pushed the supersymmetry breaking scale to several TeV or higher. Although one might expect this decoupling to have relaxed any bounds on the CP violating phases in the CMSSM, the experimental limits on EDMs, particularly the electron EDM, still allow constraints on theta(A) and theta(mu) on the order of (0.01-0.1)pi and (0.001-0.1)pi, respectively. We also discussed the impact of future experimental improvements on supersymmetric models.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yann Mambrini, Natsumi Nagata, Keith A. Olive, Jiaming Zheng
