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We study the level of primordial non-Gaussianity in slow-roll two-field inflation. Using an analytic formula for the nonlinear parameter f_nl in the case of a sum or product separable potential, we find that it is possible to generate…

Astrophysics · Physics 2011-07-13 Christian T. Byrnes , Ki-Young Choi , Lisa M. H. Hall

We develop a mathematical construction of non-Gaussian fields whose bispectra satisfy the single-clock inflation consistency relation. At the same order that our basis for bispectra recovers the two simplest single clock templates, we also…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Bekir Baytaş , Sarah Shandera

We discuss duality in $N=1$ SUSY gauge theories in Seiberg's conformal window, $(3N_c/2)<N_f<3N_c$. The 't Hooft consistency conditions -- the basic tool for establishing the infrared duality -- are considered taking into account higher…

High Energy Physics - Theory · Physics 2014-11-18 Ian I. Kogan , Mikhail Shifman , Arkady Vainshtein

In this work, we study general features of a regime where gauge fields produced during inflation cause a strong backreaction on the background evolution and its impact on the spectrum and the correlation length of gauge fields. With this…

General Relativity and Quantum Cosmology · Physics 2023-11-08 R. Durrer , O. Sobol , S. Vilchinskii

Multifield models of inflation with nonminimal couplings are in excellent agreement with the recent results from {\it Planck}. Across a broad range of couplings and initial conditions, such models evolve along an effectively single-field…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-08 David I. Kaiser , Evangelos I. Sfakianakis

Non-Gaussianity generated in inflation can be contributed by two parts. The first part, denoted by $f_{NL}^{\delta N}$, is the contribution from four-point correlation of inflaton field which can be calculated using $\delta N$ formalism,…

General Relativity and Quantum Cosmology · Physics 2017-09-06 Xiao-Min Zhang , Hong-Yang Ma , Peng-Cheng Chu , Jian-Yang Zhu

We investigate three different possibilities for improving the fermion mass relations that arise in grand unified theories (GUTs). Each scenario relies on supersymmetric loop effects alone, without modifying the naive Yukawa unification.…

High Energy Physics - Phenomenology · Physics 2009-09-29 J. Lorenzo Diaz-Cruz , Hitoshi Murayama , Aaron Pierce

In any realistic particle physics model of inflation, the inflaton can be expected to couple to other fields. We consider a model with a dilaton-like coupling between a U(1) gauge field and a scalar inflaton. We show that this coupling can…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Neil Barnaby , Ryo Namba , Marco Peloso

We discuss non-Gaussianity and baryonic isocurvature fluctuations in the curvaton scenario, assuming that the baryon asymmetry of the universe originates only from the decay products of the inflaton. When large non-Gaussianity is realized…

High Energy Physics - Phenomenology · Physics 2009-02-02 Takeo Moroi , Tomo Takahashi

Non-attractor inflation is known as the only single field inflationary scenario that can violate non-Gaussianity consistency relation with the Bunch-Davies vacuum state and generate large local non-Gaussianity. However, it is also known…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-08 Yi-Fu Cai , Xingang Chen , Mohammad Hossein Namjoo , Misao Sasaki , Dong-Gang Wang , Ziwei Wang

An interesting problem in synchronization is the study of coupled oscillators, wherein oscillators with different natural frequencies synchronize to a common frequency and equilibrium phase difference. In this paper, we investigate the…

Dynamical Systems · Mathematics 2014-05-13 Vishaal Krishnan , Arun D. Mahindrakar , Somashekhar S. Hiremath

We study the tensor spectral index $n_t$ and the tensor-to-scalar ratio $r$ in the simplest multifield extension to single-field, slow-roll inflation models. We show that multifield models with potentials $V \sim \sum_i \lambda_i…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Layne C. Price , Hiranya V. Peiris , Jonathan Frazer , Richard Easther

The trispectrum is at least as important as the bispectrum and its size can be characterized by two parameters $\tau_{NL}$ and $g_{NL}$. In this short paper, we focus on the Multi-brid inflation, in particular the two-brid inflation model…

High Energy Physics - Theory · Physics 2009-05-29 Qing-Guo Huang

We point out that a light scalar field fluctuating around a symmetry-enhaced point can generate large non-Gaussianity in density fluctuations. We name such a particle as an "ungaussiton", a scalar field dominantly produced by the quantum…

Astrophysics · Physics 2009-06-23 Teruaki Suyama , Fuminobu Takahashi

A pressing problem in comparing inflationary models with observation is the accurate calculation of correlation functions. One approach is to evolve them using ordinary differential equations ("transport equations"), analogous to the…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-10 David Seery , David J. Mulryne , Jonathan Frazer , Raquel H. Ribeiro

The question of deriving general force/flux relationships that apply out of the linear response regime is a central topic of theories for nonequilibrium statistical mechanics. This work applies an information theory perspective to compute…

Statistical Mechanics · Physics 2019-02-04 David M. Rogers

The incoherent state of the Kuramoto model of coupled oscillators exhibits marginal modes in mean field theory. We demonstrate that corrections due to finite size effects render these modes stable in the subcritical case, i.e. when the…

Adaptation and Self-Organizing Systems · Physics 2009-11-13 Michael A. Buice , Carson C. Chow

We study the effects of non-trivial initial quantum states for inflationary fluctuations within the context of the effective field theory for inflation constructed by Cheung et al. which allows us to discriminate between different initial…

High Energy Physics - Theory · Physics 2013-11-20 Nishant Agarwal , R. Holman , Andrew J. Tolley , Jennifer Lin

We show that in hybrid inflation it is possible to generate large second-order perturbations in the cosmic microwave background due to the instability of the tachyonic field during preheating. We carefully calculate this effect from the…

Astrophysics · Physics 2009-11-11 Neil Barnaby , James M. Cline

We present a simple way to calculate non-Gaussianity in inflation using fully non-linear equations on long wavelengths with stochastic sources to take into account the short-wavelength quantum fluctuations. Our formalism includes both…

Astrophysics · Physics 2009-11-10 G. I. Rigopoulos , E. P. S. Shellard , B. J. W. van Tent