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Makoto Nakamura

Publications and source records attributed to Makoto Nakamura.

25 records · Page 2Linked to original sources
arXiv2010

Fate of the False Vacuum Revisited

We find the novel effect on the decay of a false vacuum in view of quantum field theory, which is induced by a field coupling to the scalar field related to a first-order phase transition. This effect of the environment can never be included in the traditional method using the effective potential, and, in fact, acts as dissipative and fluctuation effects on tunneling phenomena. We show that the decay of the false vacuum is drastically either enhanced or suppressed. It is also clarified what kind of interaction enhance or suppress the tunneling probability.

hep-ph↗
arXiv2007

Global Existence and Uniqueness of Solutions to the Maxwell-Schr{ö}dinger Equations

The time local and global well-posedness for the Maxwell-Schr{ö}dinger equations is considered in Sobolev spaces in three spatial dimensions. The Strichartz estimates of Koch and Tzvetkov type are used for obtaining the solutions in the Sobolev spaces of low regularities. One of the main results is that the solutions exist time globally for large data.

math.AP↗
arXiv2006

On the enhancement of nuclear reaction rates in high-temperature plasma

We argue that the Maxwellian approximation can essentially underestimate the rates of some nuclear reactions in hot plasma under conditions very close to thermal equilibrium. This phenomenon is demonstrated explicitly on the example of reactions in self-sustained DT fusion plasma with admixture of light elements X = Li, Be, C. A kinetic analysis shows that the reactivity enhancement results from non-Maxwellian knock-on perturbations of ion distributions caused by close collisions with energetic fusion products. It is found that although the fraction of the knock-on ions is small, these particles appreciably affect the D+X and T+X reaction rates. The phenomenon discussed is likely to have general nature and can play role in other laboratory and probably astrophysical plasma processes.

physics.plasm-ph↗
arXiv2004

Global existence of solutions to multiple speed systems of quasilinear wave equations in exterior domains

In this paper we prove global existence for certain multispeed Dirichlet-wave equations with quadratic nonlinearities outside of obstacles. We assume the natural null condition for systems of quasilinear wave equations with multiple speeds. The null condition only puts restrictions on the self-interactions of each wave family. We use the method of commuting vector fields and weighted space-time $L^2$ estimates.

math.AP↗
arXiv2004

Global existence of quasilinear, nonrelativistic wave equations satisfying the null condition

We prove global existence of solutions to multiple speed, Dirichlet-wave equations with quadratic nonlinearities satisfying the null condition in the exterior of compact obstacles. This extends the result of our previous paper by allowing general higher order terms. In the currect setting, these terms are much more difficult to handle than for the free wave equation, and we do so using an analog of a pointwise estimate due to Kubota and Yokoyama.

math.AP↗
arXiv2004

Local well-posedness for the Maxwell-Schrödinger equation

Time local well-posedness for the Maxwell-Schrödinger equation in the coulomb gauge is studied in Sobolev spaces by the contraction mapping principle. The Lorentz gauge and the temporal gauge cases are also treated by the gauge transform.

math.AP↗