Takehiko T. Fujishiro

THE COSMIC STRINGS GENERATED FROM THE TORSION

The cosmic strings can be described naturally by torsion formalism which has a direct analogy with dislocations in three-dimensional crystalline solid. We have obtained an exact solution in a four-dimensional model on M2×T2 and may be expected to describe a space-time structure of our universe. The relation between the mass per unit length and the deficit angle are different from that of the Einstein theory, but can be made consistent since our model could reproduce its prediction. We could also obtain the maximum value of the mass per unit length µ~10−6(~1022g/cm) by fine tuning of a parameter, which is consistent with the recent observations.

Temperature Analysis of Laser Gain Plasma Medium in a Slab-Type RF Discharge Excited CO2 Laser Using Near Infrared Diode-Laser Absorption Spectroscopy

A novel optical method of temperature measurement was used to analyze a slab-type 40 MHz RF discharge excited CO2 laser plasma active medium. The method was based on near-infrared absorption spectroscopy with a 1.6 µm distributed-feedback (DFB) semiconductor laser. Gas temperatures from 450 to 650 K were measured at pressures of 1 to 6 kPa with discharge electrode distances of 5.0 and 7.5 mm. This method may provide a practical sensor for the real-time diagnostics of the active medium of CO2 lasers.

EXACT COSMIC STRING SOLUTIONS BASED ON THE CONTINUUM THEORY OF DISLOCATIONS

The effective action from the string compactification is studied on the manifolds with absolute parallelism. The cosmic strings can be described naturally by torsion formalism which has a direct analogy with dislocations in three-dimensional crystalline solids. We have found a stringy solution in a six-dimensional model on M4 × T2 which is compatible with that of Greene et al. and a cylindrically symmetric exact solution is obtained, which are different from the exact cosmic string solutions of the Einstein theory ever proposed. We have also obtained an exact solution in a four-dimensional model on M2 × T2 which can be considered as an example of the compactification on the noncompact manifold and may be expected to describe a space–time structure of our universe. The relation between the mass per unit length and the deficit angle is different from but can be consistent with that of the Einstein theory, since our solution could reproduce its prediction with a condition. We could also obtain the maximum value of the mass per unit length μ ~ 10−6 (~ 1022g/cm) by fine-tuning a parameter, which is consistent with recent observations. We have discussed the cosmic strings with the deficit angle larger than 2π.

What is the Role of Torsion in the Universe

The effective action from the heterotic string compactification is studied on the manifolds with absolute parallelism. The cosmic string solutions resulting from the effective action are discussed in analogy with the dislocations in three-dimensional crystalline solid. The cosmic string density is concluded to be given by the torsion tensor of space-time, which gives rise to a compactification at least in one-dimensional direction in space-time. It is shown also the contorsion tensor defines the deficit angle. We have found a stringy solution in a sixdimensional model on M 4 × T 2 which is compatible with that of Greene et al. and a cylindrically symmetric exact solution is obtained, which are different from the exact cosmic string solutions of the Einstein theory ever proposed

ARE THE COSMIC STRINGS SEEN AS THE DISLOCATIONS

The effective action from the heterotic string compactification is studied on the manifolds with absolute parallelism. The cosmic string solutions resulting from the effective action are discussed in analogy with the dislocations in 3-dimensional crystalline solid. The cosmic string density is concluded to be given by the torsion tensor of space-time, which gives rise to a compactification at least in 1-dimensional direction in space-time. It is also shown that the contorsion tensor defines the deficit angle. We have found a stringy solution in a 6-dimensional model on M4 × T2 which coincides with that of Greene et al.,5 but the string energy density depends only on torsion, therefore independent of the space-time metric.