117240226
Progress in the inflationary universe
124346945
Fluctuations in the New Inflationary Universe
This invention relates to novel rolling type athletic apparatus taking advantage of the characteristic of stilts which comprises a pair of vertical rods each consisting of two pipces telescopically connected to each other. The upper end of each vertical rod is bent to form a handle. Each rod is provided at its lower end with a wheel having a brake and a one-way clutch. A step is mounted on the upper portion of the wheel.
122674516
Point splitting regularization in a supersymmetric gauge field theory
Abstract Point splitting regularization is discussed in a supersymmetric Yang-Mills field theory. A supersymmetry and gauge invariant point-split supercurrent operator, along with the point-split lagrangian density, is constructed. A superconformal anomaly is computed.
122337528
Cosmological consequences of a hierarchical supersymmetric model
Abstract Unusual finite-temperature behavior of Witten's supersymmetric model is discussed. A high-temperature phase persists to the weak-interaction scale. Initial monopole density can be strongly suppressed and production of heavy particles is inhibited. Difficulties with baryon generation are suggested.
122607008
Goldstone and pseudo-Goldstone bosons in unified gauge-field models
118191225
Cosmological Consequences of Grand Unified Theories
119250849
Power spectra of scalar and tensor modes in modified Horava-Lifshitz gravity
In Horava-Lifshitz gravity, the extra dynamical scalar mode could play significant role in cosmology. However it has been pointed out that such a scalar may suffer from the strong coupling problem in IR. We address this issue in this paper. Our analysis shows that the scalar mode could decouple naturally at \lambda=1 due to the extra gauge symmetry. On the other hand, the fact that the scalar mode becomes ghost when 1/3<\lambda<1 is a real challenge to the theory. We try to overcome this problem by modifying the action such that the RG flow lies outside the problematic region. We discuss the cosmological implications of the action and calculate the power spectra of scalar and tensor modes.
118390460
1/R correction to gravity in the early universe
To explain the accelerated expansion of the late universe, the 1/R correction to Einstein gravity is usually considered, where R is the Ricci scalar. This correction term, if stable, is generally believed to be negligible during inflation. However, if the 1/R term is inflaton dependent, it will dramatically change the story of inflation. The entropy perturbation will naturally appear and drive the evolution of curvature perturbation outside the Hubble horizon. In a large class of models, the entropy perturbation can be made nearly scale invariant. In Einstein gravity the single-field inflation with a quartic potential has been ruled out by recent observations, but it revives when the 1/R term is turned on. The evolution of non-Gaussianities on a large scale are also studied and applied to inflation with 1/R correction. In some specific models, a large non-Gaussianity can be naturally generated outside the horizon. A recent study ruled out almost all f(R) models during the matter-dominated phase. Taking this into consideration, we are left with a limited class of model which recovers the Einstein gravity soon after reheating.
119238882
On the possibility of blue tensor spectrum within single field inflation
We present a series of theoretical constraints on the potentially viable inflation models that might yield a blue spectrum for primordial tensor perturbations. By performing a detailed dynamical analysis we show that, while there exists such possibility, the corresponding phase space is strongly bounded. Our result implies that, in order to achieve a blue tilt for inflationary tensor perturbations, one may either construct a non-canonical inflation model delicately, or study the generation of primordial tensor modes beyond the standard scenario of single slow-roll field.
118608368
Scale invariant power spectrum in Hořava-Lifshitz cosmology without matter
In this paper we investigate the physical implications of the dynamical scalar mode in pure Hořava-Lifshitz gravity on cosmology. We find that it can produce a scale-invariant power spectrum in UV era if the detailed balance condition on the action is relaxed. This indicates that the physical scalar mode may seed the large scale structure and Hořava-Lifshitz cosmology could be a qualified alternative to inflationary scenario.
118701741
Curvature perturbation spectrum in two-field inflation with a turning trajectory
We revisit a two-component inflaton model with a turning trajectory in the field space, where the field slowly rolls down along the trajectory. We consider the case when the effective mass in the direction perpendicular to the trajectory, namely the isocurvature direction, is either of the same order as or much larger than the Hubble parameter. Assuming that the turning angular velocity is small, we compute analytically the corrections to the power spectrum of curvature perturbation caused by the mediation of the heavy isocurvature perturbation, and compare our analytic results with the numerical ones. Especially, when Meff2 H2, we find that it is proportional to Meff−2. This result is consistent with the one obtained previously by an effective field theory approach.