We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1^{+9.2}_{-8.6} events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muon-like events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3sigma). In a two flavor oscillation scenario, the allowed Delta m^2 region at sin^2(2theta) is between 1.9 and 3.5 x 10^{-3} eV^2 at the 90% C.L. with a best-fit value of 2.8 x 10^{-3} eV^2.
We calculate the vacuum energy for Yang-Mills (YM) system in the background space-time M4 X S3, taking the effect of self-interaction of the YM fields into account. The compactification scale obtained by Candelas-Weinberg mechanism becomes large if the YM coupling is large. The case with an extra space S3/Zz is also considered, and it is shown that the vacuum associated with . broken gauge symmetry is unstable. In Kaluza-Klein theories,’ the effect of vacuum polarizations is expected to play important roles in stabilizing the compact space2 as well as in determining the gauge symmetry in four dimensions3 However, in almost all the calculations of quantum effects in the Kaluza-Klein scheme (except for Ref. 4), only the one-loop approximation is taken into consideration. Thus the calculation carried out so far might not reflect the quantum nature of self-interact ing system such as gravitation and YM fields which are inevitably contained in string theory. ’ The difficulty in going beyond one-loop is caused partly from the lack of appropriate method in computing the higher-loop contribution unambiguously in arbitrary dimensions. In the previous paper,6 the present authors have developed a technique to handle the YM interaction in vacuum diagrams when the background space-time metric has an extra space S ’. It is found that the approximation used in the calculation is more suitable for higher dimensions. We can study the higher-loop effects by our method similarly to the one-loop technique, even if the extra space has a complicated structure. In the present paper, we show the vacuum energy for SU(3) YM system defined in the background space-time M4 x S3, where M‘t is the flat Minkowski space-time and S3 is the three
We treat the model which describes "extreme black holes" moving slowly. We derive an effective lagrangian in the low energy for this model and then investigate a statistical behavior of "extreme black holes" in the finite temperature.
We study the interaction of maximally-charged dilatonic black holes at low velocity. We compute the metric on moduli space for three extreme black holes under a simple constraint. The Hamiltonian of the multi-black hole system of $O(v^2)$ is also calculated for the $a=1$ and $a=1/\sqrt{3}$ cases, where $a$ is the dilaton coupling constant. The behavior of the system is discussed qualitatively.
We construct the higher order terms of curvatures in Lagrangians of the scale factor in the D -dimensional Robertson-Walker metric, which are linear in the second derivative of the scale factor with respect to cosmic time. It is shown that they are composed of the Lovelock tensors at the first step; iterative construction yields arbitrarily high order terms. The relation to the former work on higher order gravity is discussed. Despite the absence of scalar degrees of freedom in cosmological models which come from our Lagrangian, it is shown that an inflationary behavior of the scale factor can be found. The application to the thick brane solutions is also studied.
We examine a model of BPS black holes lying on a discrete extra space. The geometry is obtained from the discretization of the harmonic equation. We study the scattering amplitudes of two types of scalar fields, which correspond to fields in a bulk and on a brane. We conclude that the two types of scattering can be distinguished in the region of large transfer momentum.
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