Quantum Subcritical Bubbles

We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in the quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using quantum statistical average. Furthermore based on our study, we give implication on the dynamics of phase transition.Comment: Latex file, 9pp, to be published in Progress of Theoretical Physic

Perturbation Analysis of Deformed Q-Balls and Primordial Magnetic Field

We study the excited states of the Q-balls by performing stationary perturbation on the spherical Q-balls. We find the exact solution of the stationary perturbation of the global Q-ball with thin wall approximation. For local Q-balls we solve the equations of motion for the perturbative part approximately by using expansion about the coupling constant. Furthermore we comment on the magnetic field generated by the excited Q-balls during the phase transition precipitated by solitosyhthesis and give an implication into cosmology.Comment: 11 pages, RevTex, to appear in Phys. Rev.

D-braneworld cosmology

We discuss D-braneworld cosmology, that is, the brane is described by the Born-Infeld action. Compared with the usual Randall-Sundrum braneworld cosmology where the brane action is the Nambu-Goto one, we can see some drastic changes at the very early universe: (i)universe may experience the rapid accelerating phase (ii)the closed universe may avoid the initial singularity. We also briefly address the dynamics of the cosmology in the open string metric, which might be favorer than the induced metric from the view point of the D-brane.Comment: 6 pages, 3 figures, minor corrections, accepted for publication in Phys. Rev.

X-Ray Measurement of Order in the Beta-Prime Phases of Noble Metal Alloys. I : β\u27AuZn

The long range order parameter of the β\u27AuZn alloy of the L2_0-type structure has been measured by X-ray diffraction at temperatures ranging from 200℃ to 650℃, the latter temperature being 75℃ below the melting point T_m. Relative intensities of several h00 type reflections from single crysta]s have been measured using a counter diffractometer equipped with a high temperature attachment. It has been observed that the order parameter gradually decreases with rising temperature but appears to keep an appreciably high value at T_m. An abnormal increase in the lattice spacing has also been observed at about 550℃, which corresponds to the onset of an appreciable disordering detected by the intensity measurement. It is concluded that β\u27AuZn is a special type of ordered alloy and it would undergo a transition into the disordered alloy state, if it were not melted. The root-mean-square displacement of atoms due to thermal vibration has been measured as a function of temperature. At room temperature the displacement is 0.125A, 4.6% of the nearest neighbor distance, and increases to 0.255A at 650℃