Phase transition in thiourea is discussed on the basis of a simple lattice dynamical model for the molecular rotational vibration. It is shown that a combination of the dipole-dipole interaction and the short range force can yield the soft rotational branch which has a minimum frequency at a certain finite wave vector q0. Based on this result and the consideration on the anharmonic vibrations, a free energy expression of the Landau type is given, which describes the sinusoidal antiferroelectric phase transition and the temperature dependence of the modulation wave vector. It is revealed that the temperature dependence of the modulation wave vector originates from the shift of the balance between the dipole-dipole interaction and the appropriate short range force, which is caused by the anharmonic effects of vibrations.
Gamow-Teller beta transitions between the anomalous coupling state with spin 7/2+ in odd-proton nuclei with filling 1g9/2-orbit and the 2d5/2 single-particle state in odd-neutron nuclei are calculated by the method of many-quasi-particle new-Tamm-Dancoff space. The effect of the proton-neutron correlation with spin 1+ is taken into account on an equal footing as the quadrupole correlation. Calculated results are compared to the experimental data.
The dynamic consequences of the existence of pinned vort1c1ty in a rotating superfluid are studied by means of a simple model: the behavior of a rotating cylinder which contains a uniform region of either weakly or strongly pinned vorticity and which is being spun up or spun down by an external torque. It is shown that in the case of strong pinning, spin down can lead to periodic jumps (glitches) in the rotation frequency of the cylinder, followed by quasi-oscillatory relaxation, while in the case of weak pinning no glitches occur unless the cylinder is shaken so violently that vortices unpin. We conclude that the giant glitches and post-glitch behavior observed in the Vela pulsar may be explained by the sudden release of some 10% of the strongly pinned vortices in the neutron crust every few years as a result of pulsar spin down. We further suggest that the post-glitch behavior observed in the Crab pulsar can be explained if the macroglitches represent vorticity jumps induced by small starquakes in the weakly pinned vortex region expected in the crust of a young neutron star, and that the differences in glitch be havior of the Crab, Vela, and older pul~ars may be explained on evolutionary grounds.
Anomalies have a diverse impact on many aspects of physical phenemona. The role of anomalies in determining physical structure from the amplitude for π0 decay to the foundations of superstring theory will be reviewed.
A general expression for the differential scattering cross section of neutrons by an electron system is considered in terms of the transverse current-current response function. Effect of the transverse fluctuating field on the transverse current-current response function· is found to be important. Such a calculation is made by using the transverse effective field approach formulated by Pines and Nozieres. The effect of the fluctuating transverse field appears in the final expression in the form of dynamic screening. This suppresses the other wise divergent differential cross section appreciably at smallest q of order hundredth of inverse Angstrom or less. orbital magnetism. Nevertheless, we are still left with several important pro blems to be settled, especially on the dynamic orbital magnetism. We have among them the problem of neutron scattering by orbital current carried by electrons in a metal. Neutron with nuclear spin 1/2 probes the magnetic field in a solid, which is fluctuating, generally, in space and time. This fluctuating field induces fluctuating current, and vice versa: the fluctuating magnetic field arises from the spontaneous motion of charged particles. As is well known, the total orbital current consists of two parts, paramagnetic and diamagnetic, and the latter depends linearly on the vector potential acting on the electrons that carry it. This dualism of orbital current should be considered carefully: the gauge invariance has to be maintained in any theoretical calculations. In this paper we try to construct the theory of neutron scattering by current fluctuation, taking account of the above point. We do it by follow ing the steps outlined below. In § 2 we represent the neutron scattering cross section in terms of the magnetic field-magnetic field correlation function, then express it in terms of the transverse current-current correlation function by making use of the exact microscopic Maxwell equation incorporating the electromagnetic fluctuations. The transverse current-current correlation function is related to the corres-
This talk gives a brief account of the development of particle theory from the Yukawa meson to the quark model before the prevalence of gauge theories. An emphasis will be laid on the interplay of particle theory and field theory.
Various theoretical problems concerning dynamical generation of composite gauge bosons are discussed. In particular we clarify the general mechanism how massless gauge bosons of hidden local symmetry is created dynamically. Consistency with Weinberg-Witten type no-go theorem is also clarified. We emphasize that such dynamical generations of gauge bosons, massless or massive, are rather common phenomena which can occur easily in a wide variety of systems not restricted in CPN−1 model nor in 2 dimensions. As a special example we prove generally that massless graviton must be generated dynamically in any general coordinate invariant systems as far as the background metric is flat Minkowskian.
It is difficult for me to grasp that this symposium is celebrating the jubilee of meson theory since I was a junior at Columbia College in 1935. I recall hearing a colloquium by Paul Dirac that year telling an enraptured audience about the infinite sea of negative energy states but I do not recall any special note being taken of the birth of an equally revolutionary concept, the Yukawa meson. Perhaps the reason was the publication of Hideki Yukawa's paper in an inaccessible Japanese journal, perhaps Dirac's electron theory was dealing with the well-known electromagnetic force whereas Yukawa's meson theory was put forth to understand the nature of two new forces — the nuclear and the weak. Whatever the reason, the situation changed drastically when I migrated to Cornell (to do my thesis under Hans Bethe during the years 1937 ∼ 39) and found a deep interest in meson theory. Thus, my own scientific career has almost spanned the period since the birth of meson theory but, what is more to the point, it has been strongly influenced by the work of Yukawa and his collaborators. It therefore gives me great pleasure to be able to talk at this MESON 50 symposium. As one of the oldest speakers, I shall respond in a loose way to Professor Maki's invitation to cover “topics concerning the historical developments of hadron physics”. I shall select several major themes from the Japanese work that have had special interest for me. My remarks will fall under the four headings: (A) Yukawa Meson; (B) Sakata Model; (C) Baryon-Lepton Symmetry; and (D) Extensions of Baryon-Lepton Symmetry.
It is a great honour to participate at the Jubilee Conference in Kyoto devoted to 50 years of Hideki Y ukawa brilliant prediction of mesons, moreover acting as a chairman of a session. First of all I am obliged to convey to Professor Ziro Maki, Chairman of the Organizing Committee of MESON50, the best wishes for the success of the Conference from the Rector of the Moscow University (Professor A. Logunov) and the Dean of its Physics Faculty (Professor V. Fursov) recalling that Professor H. Yukawa was a Doctor honoris causa of our University. It may be permitted to myself to remind our long term colleagial, friendly relations with unforgettable Yukawa, his deep attention to our papers, also his, now rather widely known famous inscription with a chalk on the wall of my working cabinet at Physics Faculty, made after discussions at a workshop: "Nature is simple in its essence", has written Yukawa, formulating so to say his motto, reflecting his deep philosophical conceptions, also in a_ sense "polemicizing" with motto of P. A. M. Dirac, previously also written with chalk : "Physical law should have mathematical beauty" (1956). (Both precious inscriptions, together with two others, brought later by Niels Bohr and ]. A. Wheeler, are preserved under glass.) H. Yukuwa visited Soviet Union in 1959, participating at the 9th Conference on High Energy Physics in Kiev~ and afterwards visited Moscow. Not entering in details I intend to draw attention on some important points of the early years of the whole modern nuclear physics, as well as the theory of elementary particles, reminding first of all some most difficult points of the establishing protonneutron nuclear model, proposed by me (April 1932) after the discovery of the neutron by Chadwick (February 1932). It is well known that the old proton-electron constitution of nuclei met with many serious difficulties, being not capable to explain spins, statistics, magnetic moments, etc., of nuclei. It was felt at the end of 20's and beginning of 30's, that something radical must be done, e.g., Niels Bohr suggested the construction of a quite new theory of "nuclear electrons" based on his beloved non-conservation of energy. One has spoken about the loosing of spin, etc., by internuclear electrons ( cf. Beitler), tried to change the Minkowskian relativistic flat space-time geometry inside nuclei (trying to solve simultaneously the divergence of electromagnetic field energy problem of point electron by introducing a kind of discrete space-time lattice, cf. D. Ivanenko and V. A. Ambarzumian, also W. Heisenberg, 1930). All this was wrong! But our analysis of the behaviour of leptonic type so light electrons in small distances proved to be useful later ; the hypothesis of a lattice space-time, independently from nuclear problems was, let us remark by the way in itself interesting and stimulated many investigations, continued in modernized form up to recent days, cf. Darling, Schild, Rompe, Moeglich, Snyder, Finkelstein, Caldirola and other authors; perhaps indeed, not at nuclear distances ~ 10cm, but at Planckian "smallest" distances ~ 10-cm, some kind of discreteness arises?
An analysis of the spontaneous breaking of chiral symmetry in three dimensional electrodynamics is described. It is argued that this model, when treated in a 1/ N expansion, does exhibit spontaneous chiral symmetry breaking. This is established by finding analytic and numer· ical solutions to the Dyson-Schwinger equation and then computing the composite-operator effective potential. During the fifty years since Y uka wa proposed the J[ meson as the intermediary of nuclear forces, our view of this particle has continued to evolve. We now know it to be a quark-antiquark composite, and in quantum chromodynamics, QCD, we have a strong interaction theory that may well describe its dynamics and that of the other hadrons. Among all the hadrons, however, the 1f meson is believed to play a special role. The underlying theory of strong interactions posseses a near chiral symmetry, SU(2h X SU(2) R, because of the approximate masslessness of the up and down quarks. This symmetry must then break spontaneously in order to explain the effective 300 MeV masses that these quarks appear to possess as the constituents of hadrons. The spontaneous breaking of any continuous symmetry necessarily leads to the existence of massless Goldstone bosons, and in the case of chiral symmetry, the 1f mesons approximately play this role. The small bare mass of the up and down quarks leads to a small mass for 1f mesons 1
