arXiv subjects

M. Bucher

Publications and source records attributed to M. Bucher.

130 records · Page 8Linked to original sources

arXiv1997

Primordial Gravitational Waves From Open Inflation

We calculate the spectrum of gravitational waves generated during inflation in open $(Ω_0<1)$ inflationary models. In such models an initial epoch of old inflation solves the horizon and flatness problems, and during this first epoch of inflation the quantum state of the graviton field rapidly approaches the Bunch-Davies vacuum. Then old inflation ends by the nucleation of a single bubble, inside of which there is a shortened epoch of slow-roll inflation giving $Ω_0<1$ today. In this paper we re-express the Bunch-Davies vacuum for the graviton field in terms of the hyperbolic modes inside the bubble and propagate these modes forward in time into the present era. We derive the expression for the contribution from these gravity waves to the cosmic microwave background anisotropy including the effect of a finite energy difference across the bubble wall.

astro-ph↗

arXiv1995

An Open Universe from Inflation

We present a natural scenario for obtaining an open universe ($Ω_0<1$) through inflation. In this scenario, there are two epochs of inflationary expansion---an epoch of `old inflation,' during which the inflaton field is stuck in a false vacuum, followed by an epoch of `new inflation,' during which the inflaton field slowly rolls toward its true minimum. During the first epoch, inflation solves the smoothness and horizon problems. Then an open universe (with negative spatial curvature) is created by the nucleation of a single bubble. In effect $Ω$ is instantaneously `reset' to zero. During the subsequent `new' inflation $Ω$ rises toward unity. The value of $Ω$ today is calculable in terms of the parameters of the potential, and we show that obtaining values significantly different from zero or unity (though within the range $0<Ω<1$) does not require significant fine tuning. We compute the spectrum of density perturbations by evolving the Bunch-Davies vacuum modes across the bubble wall into its interior.

hep-ph↗

arXiv1995

$Ω_0 <1$ From Inflation

An inflationary scenario that leads to $Ω_0<1$ today is presented. An epoch of `old' inflation during which the smoothness and horizon problems are solved is followed by a shortened epoch of `new' inflation. Old inflation exits through the nucleation of a single bubble, leading to negative spatial curvature on slices of constant cosmic time. We calculate the spectrum of density perturbations in such a scenario.

hep-ph↗

arXiv1993

SO(10) Cosmic Strings and SU(3) Color Cheshire Charge

Certain cosmic strings that occur in GUT models such as $SO(10)$ can carry a magnetic flux which acts nontrivially on objects carrying $SU(3)_{color}$ quantum numbers. We show that such strings are non-Abelian Alice strings carrying nonlocalizable colored ``Cheshire" charge. We examine claims made in the literature that $SO(10)$ strings can have a long-range, topological Aharonov-Bohm interaction that turns quarks into leptons, and observe that such a process is impossible. We also discuss flux-flux scattering using a multi-sheeted formalism.

hep-ph↗