118697879
TIME DEPENDENT VARIATIONAL PRINCIPLE FOR QUANTUM DYNAMICS IN THE SCHRODINGER PICTURE
Starting with the exact variational formulation of quantum mechanics (or quantum field theory) in the Schroedinger picture, and using Gaussian trail wave functions, an exact functional Schroedinger equation is obtained. The time-dependent Hartree-Fock approximation is obtained and extended to many oscillators and to field theory. The problem of quantum roll, in which an initial Gaussian wave packet starting at an unstable classical equilibrium point evolves in time, is treated using this formalism. Quantum tunnelling is also studied. (LEW)
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.
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.
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.
122607008
Goldstone and pseudo-Goldstone bosons in unified gauge-field models
118191225
Cosmological Consequences of Grand Unified Theories
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.
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.
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.
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.
117214043
Cosmological perturbations in inflation with multiple sound speeds
Abstract We study a multi-field inflationary theory with separable Lagrangian, which has different speed of sound for each field. We find that the fields always coupled at perturbative level through gravitational interaction. We show that if the coupling terms among the perturbation fields are weak enough, these fields can be treated as a combination of decoupled fields, which are similar to normal modes in coupled oscillation. By virtue of such fields, the curvature perturbation at horizon crossing can be calculated up to the leading order of slow-variation parameters via δ N formalism. Explicitly, we consider a model of multi-speed DBI inflation, and calculate the power spectrum in detail. The result depends on the ratio of different speeds of sound, and shows an apparent amplification when the ratio deviates from unity.