Article
Astronomy & Astrophysics
So Okano, Tomohiro Fujita
Summary: This study numerically investigates the occurrence of Schwinger preheating in different inflation models and finds that it only occurs when there is a sufficiently large coupling between the inflaton and photons in the Starobinsky inflation model.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Perseas Christodoulidis, Robert Rosati
Summary: We explore the dynamics of multi-field inflationary models in detail, analyzing the two-field case and providing elegant expressions for the three-field case. We observe the common occurrence of field-space isometries and their usefulness in obtaining attractor solutions and stability. We also apply our discussion to concrete supergravity models.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Diptimoy Ghosh, Amartya Harsh Singh, Farman Ullah
Summary: We study the analytic structure of in-in correlation functions in a deSitter background to probe the initial conditions for inflation. We emphasize the flexibility of vacuum choices and clarify their role in calculations and diagrammatic interpretation. By considering various possibilities and examining pole structures, such as adding excitations and coherent states, we shed light on the missing details that link quantum and classical initial conditions, and aim to enhance our understanding of in-in correlators in inflation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Dong-Gang Wang, Guilherme L. Pimentel, Ana Achucarro
Summary: Primordial non-Gaussianities from multi-field inflation are studied in this paper, with a focus on the nonlinear conversion process from additional light scalars into curvature perturbations. Analytic templates for correlation functions at any kinematical configuration are provided using the cosmological bootstrap. The results include the possibility of large breaking of boost symmetry and small speeds of sound for both the inflaton and the mediators. The symmetry constraints on the correlators are found to be modified by introducing a late-time cutoff, leading to anomalous conformal Ward identities.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nashwan Sabti, Julian B. Munoz, Diego Blas
Summary: UV luminosity functions provide valuable information on galaxy formation physics in the early Universe and have the potential to constrain alternative theories of structure formation. By using the Hubble Space Telescope measurements, researchers in this work were able to derive a constraint on the non-Gaussianity parameter f(NL) for wavenumbers above a cut-off scale, with a predicted improvement of 3-4 times on current bounds for future observations with the James Webb Space Telescope and the Nancy Grace Roman Space Telescope.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Dionysios Karagiannis, Jose Fonseca, Roy Maartens, Stefano Camera
Summary: The 21 cm emission line of neutral hydrogen can trace dark matter after reionisation; Next-generation intensity mapping surveys may serve as probes of primordial non-Gaussianity; Single-dish surveys typically outperform interferometer surveys in power spectrum but are not competitive in bispectrum.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
Dhiraj Kumar Hazra, Daniela Paoletti, Ivan Debono, Arman Shafieloo, George F. Smoot, Alexei A. Starobinsky
Summary: In this study, constraints on inflationary dynamics and features in the primordial power spectrum of scalar perturbations are presented using Cosmic Microwave Background temperature and polarization data from Planck 2018 data release. Models with suppression and oscillatory features are analyzed and compared with baseline slow-roll potentials. The significance of sharp features has decreased compared to previous data analysis, and bispectra are computed for the best fit candidates obtained from the analysis.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mehrdad Mirbabayi, Andrei Gruzinov
Summary: Sphaleron heating is proposed as a mechanism for warm inflation when the inflaton is coupled to pure Yang-Mills as an axion. The presence of heating introduces a friction coefficient gamma proportional to T-3 in the inflaton's equation of motion, as well as a thermal contribution to cosmological fluctuations. In the absence of knowledge about the inflaton potential, non-Gaussianity is the most promising approach for detecting the signatures of this model. By extending previous work, we compute the scalar three-point correlation function and identify distinct features in the squeezed and folded limits. As a detection strategy, we find that combining the equilateral template with a new template yields a high overlap with the shape of non-Gaussianity for 0.01 <= gamma/H <= 1000, with 0.7 < |f(NL)| < 50 in this range.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Guillermo Ballesteros, Marcos A. G. Garcia, Mathias Pierre
Summary: This study investigates the power spectrum of Non-Cold Dark Matter produced in a state out of thermal equilibrium, considering various sources of dark matter production. A mapping procedure is proposed to translate the WDM Lyman-alpha mass bound to NCDM scenarios, providing bounds on several NCDM possibilities. The results have implications for specific examples of dark matter scenarios.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ananya Tapadar, Sougata Ganguly, Sourov Roy
Summary: In this paper, the non-adiabatic evolution of dark sector is studied in the framework of a U(1)(L mu)-( L tau )circle times U(1)(x) extension of the standard model. The connection between the visible and dark sectors is established through a portal coupling. The temperature evolution and various non-equilibrium stages of the dark sector are analyzed. Constraints on the model parameters from laboratory and astrophysical searches are investigated. The parameter space for the non-adiabatic evolution of the dark sector is significantly constrained for certain values of mass and coupling, while other constraints depend on the mass ratio.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Chong-Bin Chen, Jiro Soda
Summary: This paper studies the effect of the geometry of multi-form field space on an inflationary scenario, clarifies the conditions for the onset of destabilization, reveals the geometric structure of attractors after destabilization, and investigates the features of primordial fluctuations. Several phenomenological predictions are made based on the calculations of the power spectrum.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Raul Henriquez-Ortiz, Jorge Mastache, Saul Ramos-Sanchez
Summary: With new missions to explore spectral distortions of the cosmic microwave background with unprecedented precision, the study of theoretical predictions of these signals becomes a promising avenue to test our understanding of the early Universe. Axion monodromy provides a viable framework for describing cosmic inflation, but its falsifiability is challenged by the need for higher precision observational data.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Areste Salo, D. Benisty, E. Guendelman, J. D. Haro
Summary: A new type of quintessential inflation based on the Lorentzian distribution has been introduced, with a simple potential that aligns with recent observations and depicts the acceleration of the universe, including reheating constraints.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Aliki Litsa, Katherine Freese, Evangelos I. Sfakianakis, Patrick Stengela, Luca Visinellij
Summary: We propose a new way of studying the Higgs potential at extremely high energies by considering the space dependence and non-Gaussianity of the resulting temperature anisotropy spectrum. The observed temperature anisotropies in the Cosmic Microwave Background (CMB) are largely excluded to be primarily caused by Higgs effects. Observational searches for non-Gaussianity in the CMB can be used to constrain the dynamics of the Higgs boson at very high energies.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Mar Bastero-Gil, Antonio Torres Manso
Summary: We present a supersymmetric extension of a unified model for inflation and Dark Matter, which is based on the incomplete decay of the inflaton field into right-handed neutrino pairs. By imposing a discrete interchange symmetry on the inflaton and right-handed neutrinos, stability of the inflaton field at the global minimum is ensured, while still allowing partial decay and reheating of the Universe. Compatibility with inflationary predictions, BBN bounds, and obtaining the right DM abundance typically requires large couplings to the neutrino sector.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Multidisciplinary
Anson Hook, Soubhik Kumar, Zhen Liu, Raman Sundrum
PHYSICAL REVIEW LETTERS
(2020)
Article
Physics, Particles & Fields
Soubhik Kumar, Raman Sundrum
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Physics, Particles & Fields
Kaustubh Agashe, Peizhi Du, Majid Ekhterachian, Soubhik Kumar, Raman Sundrum
Summary: This study focuses on the cosmological transition of 5D warped compactifications, demonstrating the percolation of bubbles of IR-brane nucleating from the black-brane horizon. Through semiclassical treatment of bubble nucleation, a smooth 5D bounce configuration is introduced to control the transition rate effectively. The generalization of the Goldberger-Wise mechanism modifies the IR-brane dynamics for a quicker transition, resolving issues related to supercooling and inconsistencies with data.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Arushi Bodas, Soubhik Kumar, Raman Sundrum
Summary: Non-analyticity in co-moving momenta within the non-Gaussian bispectrum is a distinctive sign of on-shell particle production during inflation. A combination of dimension-5 derivative couplings and chemical potential form operator provides an exception to the usual exponential drop in non-analyticity at masses exceeding the inflationary Hubble scale. This mechanism allows for the direct detection of particles with masses potentially as high as 10^(15) GeV, within the sensitivity of upcoming experiments.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Kaustubh Deshpande, Soubhik Kumar, Raman Sundrum
Summary: Hybrid Inflation is a well-motivated mechanism for cosmic inflation, but faces hierarchy problems; by introducing a discrete twin symmetry, these issues can be addressed, leading to a natural model of non-supersymmetric low-scale inflation.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Soubhik Kumar, Raman Sundrum, Yuhsin Tsai
Summary: Cosmological phase transitions in the primordial universe can generate anisotropic stochastic gravitational wave backgrounds, some of which are related to the cosmic microwave background, and some may exhibit significant non-Gaussianity. By using gravitational wave detectors, it is possible to detect the isocurvature component in the gravitational wave background, opening up a new possibility for observation.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Jeong Han Kim, Soubhik Kumar, Adam Martin, Yuhsin Tsai
Summary: During inflation, heavy particles can be non-adiabatically pair produced through their couplings to the inflaton, resulting in non-trivial spatial distribution of curvature perturbations. This phenomenon generates localized hot spots on the CMB and modifies the CMB power spectra and bispectra, although current measurements are not sensitive to these corrections.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Subhajit Ghosh, Soubhik Kumar, Yuhsin Tsaia
Summary: Dark radiation is a potential candidate beyond the Standard Model, and its perturbations can have isocurvature components under certain conditions. This study derives constraints on uncorrelated and correlated dark radiation density isocurvature perturbations and explores the differences between free-streaming dark radiation and coupled dark radiation. The preference for a blue-tilt dark radiation isocurvature spectrum is found, which affects the estimation of the Hubble constant and relaxes the H-0 tension.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Joshua W. Foster, Soubhik Kumar, Benjamin R. Safdi, Yotam Soreq
Summary: The study demonstrates that the quantum chromodynamics axion with a decay constant near the Grand Unification (GUT) scale has an ultralight mass near a neV, and axionlike particles with masses near the keV-PeV range and GUT-scale decay constants are also well motivated in axiverse theories with dark nonabelian gauge groups. By combining the misalignment mechanism with a period of early matter domination from the long-lived dark glueballs of the same gauge group, the heavy axions in these models can achieve the correct dark matter abundance. The decay of heavy axion dark matter into two photons may produce mono-energetic electromagnetic signatures that can be detected by current or next-generation space-based telescopes.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
R. Acciarri, C. Adams, B. Baller, V. Basque, F. Cavanna, R. T. Co, R. S. Fitzpatrick, B. Fleming, P. Green, R. Harnik, K. J. Kelly, S. Kumar, K. Lang, I. Lepetic, Z. Liu, X. Luo, K. F. Lyu, O. Palamara, G. Scanavini, M. Soderberg, J. Spitz, A. M. Szelc, W. Wu, T. Yang, ArgoNeuT Collaboration
Summary: We present the results of a search for heavy QCD axions performed by the ArgoNeuT experiment at Fermilab. We search for heavy axions produced in the NuMI neutrino beam target and absorber decaying into dimuon pairs, which can be identified using the unique capabilities of ArgoNeuT and the MINOS near detector. We obtain new constraints at a 95% confidence level for heavy axions in the previously unexplored mass range of 0.2-0.9 GeV, for axion decay constants around tens of TeV.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Particles & Fields
Raymond T. Co, Soubhik Kumar, Zhen Liu
Summary: Heavy QCD axions are extensions of the QCD axion that solve the strong CP problem while also addressing the quality problem. These axions, with large decay constants up to PeV, can be produced in significant numbers at beam dump and collider environments. They can decay into long-lived lepton pairs, particularly muons, in a broad class of axion models. Current and future neutrino facilities and long-lived particle searches have the potential to probe significant parts of the heavy QCD axion parameter space through dimuon final states, considering existing constraints primarily from rare meson decays.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Simon Knapen, Soubhik Kumar, Diego Redigolo
Summary: We investigated the physics case for a dedicated trigger-level analysis for very low mass diphoton resonances at ATLAS and CMS, and introduced a new photon isolation criterion. This significantly increases the acceptance for light particles at the cost of a somewhat larger Standard Model background. We showed how such an analysis would likely provide new experimental coverage for axionlike particles below 15 GeV, bridging the gap with the region covered by flavor factories.
Article
Astronomy & Astrophysics
Majid Ekhterachian, Anson Hook, Soubhik Kumar, Yuhsin Tsai
Summary: The article discusses new bounds on vectors coupled to currents with nonconservation due to mass terms and their growth characteristics. Constraints from the high transverse mass tail of monolepton + MET events at the LHC provide strong limits for most masses below a few keV in Stueckelberg U(1)(L mu-L tau) models.
Article
Astronomy & Astrophysics
Kevin J. Kelly, Soubhik Kumar, Zhen Liu
Summary: Recent research has discovered the potential of heavy axions to solve both the strong CP problem and the axion quality problem, requiring exploration in collider and beam dump environments. The near detector of the Deep Underground Neutrino Experiment has a unique sensitivity to heavy axions in the mass range of 20 MeV to 2 GeV, complementing other future experiments.