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C. W. Kim

Publications and source records attributed to C. W. Kim.

46 records · Page 3Linked to original sources
arXiv1995

Some Remarks on Nu(mu)-Nu(e) Oscillations of Terrestrial Neutrinos and Atmospheric Neutrino Oscillations

We present the results of an analysis of the data of reactor and accelerator neutrino oscillation experiments in the framework of a model with mixing of three massive neutrino fields and a neutrino mass hierarchy. The results of the LSND experiment are commented. Taking into account future long-baseline neutrino oscillation experiments, we have also analyzed the atmospheric neutrino data in the framework of the model.

hep-ph↗
arXiv1995

Atmospheric Neutrino Problem in Maximally-Mixed Three Generations of Neutrinos

Motivated by the indication that both the atmospheric and the solar neutrino puzzles may simultaneously be solved by (vacuum as well as matter-induced resonant) oscillations of two generations of neutrinos with large mixing, we have analyzed the data on the atmospheric and solar neutrinos assuming that all {\it three} neutrinos are maximally mixed. It is shown that the values of $ Δm^2 $ obtained from the two-generation analyses are still valid even in the three-generation scheme, i.e. the two puzzles can be solved simultaneously if $ Δm_{31}^2 \simeq 10^{-2} \, \mathrm{eV}^2 $ for the atmospheric neutrinos and $ Δm_{21}^2 \simeq 10^{-10} \, \mathrm{eV}^2 $ for solar neutrinos in the maximally mixed three-generation scheme.

hep-ph↗
arXiv1995

A New Scale-Dependent Cosmology with the Generalized Robertson--Walker Metric and Einstein Equation

Based on the observed increase of $Ω_0$ as a function of cosmic scale, the Robertson--Walker metric and the Einstein equation are generalized so that $ Ω_0$, $H_0$, and the age of the Universe, $t_0$, all become functions of cosmic scales at which we observe them. The calculated local (within our galaxy) age of the Universe is about 18 Gyr, consistent with the ages of the oldest stars and globular clusters in our galaxy, while the ages at distant scales are shorter than the local age, solving the age puzzle. It is also shown that $H_0$ increases as scale increases, qualitatively consistent with the recent observations.

hep-ph↗
arXiv1995

Effects of the Running Gravitational Constant on the Amount of Dark Matter

The amount of dark matter in the Milky Way and beyond is examined by taking into account the possible running of the gravitational constant $G$ as a function of distance scale. If the running of $G$, as suggested by the Asymptotically-Free Higher-Derivative quantum gravity, is incorporated into the calculation of the total dark matter in the galactic halo, the amount of dark matter that is necessary to explain the rotation curve is shown to be reduced by one third compared with the standard calculations. However, this running of $G$ alone cannot reproduce the observed flat behavior of the rotation curve. It is also shown that the running of $G$ cannot explain away the presence of most of the dark matter beyond the scale of $ \sim 10$ Mpc in the Universe. We also present a pedagogical explanation for the running of $G(r)$ in the region of large scales which is clearly a classical domain.

astro-ph↗
arXiv1994

Do the Age of the Universe and the Hubble Constant Depend on What Scale One Observes Them?

The apparent cosmological conflict between the age of the Universe, predicted in the standard Friedman cosmology by using the recent measurement of the larger Hubble constant from a direct calibration of the distance to the Virgo galaxy cluster, and the ages of the oldest stars and globular clusters is resolved by invoking the scale dependence of cosmological quantities, including the age of the Universe. The distance dependence or the running of cosmological quantities is motivated by the asymptotically-free higher- derivative quantum gravity. The running can also be derived by ``properly" modifying the Friedman equations. This property can also provide partial explanation of the apparent disagreement between the two recent measurements of the Hubble constant using NGC 4571 at 15 Mpc and NGC 5253 at 4 Mpc.

hep-ph↗
arXiv1993

Maximally-Mixed Three Generations of Neutrinos and the Solar and Atmospheric Neutrino Problems

Motivated by the indication that both the Solar and the atmospheric neutrino puzzles may simultaneously be solved by (vacuum as well as matter-induced resonant) oscillations of two generations of neutrinos with large mixing, we have analyzed the data on the Solar and atmospheric neutrinos assuming that all {\it three} neutrinos are maximally mixed. It is shown that the results of two-generation analyses are still valid even in the three-generation scheme, {\it i.e.}, the two puzzles can be solved simultaneously if $Δm_{21}^2 = m_2^2-m_1^2\simeq 10^{-10}\mbox{eV}^2$ and $Δm_{31}^2 = 10^{-3}\sim 10^{-1}\mbox{eV}^2$. We have also demonstrated explicitly that with the use of the see-saw mechanism it is possible to have large or maximal mixings for neutrinos even though their masses are highly non-degenerate.

hep-ph↗
arXiv1993

On the Treatment of Neutrino Oscillations Without Resort to Weak Eigenstates

We discuss neutrino oscillations in the framework of the quantum field theory without introducing the concept of neutrino weak eigenstates. The external particles are described by wave packets and the different mass eigenstate neutrinos propagate between the production and detection interactions, which are macroscopically localized in space-time. The time-averaged cross section, which is the measurable quantity in the usual experimental setting, is calculated. It is shown that only in the extremely relativistic limit the usual quantum mechanical oscillation probability can be factored out of the cross section.

hep-ph↗
arXiv1993

Fermion and Anti-Fermion Effective Masses in High Temperature Gauge Theories in $CP$-Asymmetric Background

We calculate the splitting between fermion and anti-fermion effective masses in high temperature gauge theories in the presence of a non-vanishing chemical potential due to the $CP$-asymmetric fermionic background. In particular we consider the case of left-handed leptons in the $SU(2)\otimes U(1)$ theory when the temperature is above $250$ GeV and the gauge symmetry is restored.

hep-ph↗
arXiv1992

Oscillations of Pseudo-Dirac Neutrinos and the Solar Neutrino Problem

The oscillations of pseudo-Dirac neutrinos in matter are discussed and applied to the solar neutrino problem. Several scenarios such as both $ν_e$ and $ν_μ$ being pseudo-Dirac and only $ν_e$ or $ν_μ$ being pseudo-Dirac are examined. It is shown that the allowed region in the mass-mixing angle parameter space obtained by comparing the solar neutrino data with the calculations based on the standard solar model and the MSW effect is not unique. The results depend on the nature of neutrinos; for example, if both $ν_e$ and $ν_μ$ are pseudo-Dirac, the allowed region determined by the current solar neutrino data does not overlap with that obtained in the usual case of pure Dirac or Majorana neutrinos.

hep-ph↗