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Recent developments in particle symmetries
Book'Reviews problem. The ability to make such judgments comes, if at all, only after at least some experience with the "non-elegant" handling of simple problems. A certain preacher once explained how he approaches his audience: "First I tell them what I am going to tell them. Then I tell them; and then I tell them what I've told them." Feynman's Lectures constitute an excellent example for both the first and the last stages in this three-step process. The second stage students may be advised to consult the more conventional texts. AMOSDE SttALIT
Weizmann Institute of Science Rehovoth, Israel RECENT DEVELOPMENTS IN PARTICLE SYMMETRIES, edited by A. Zichichi. 460 pages, diagrams, 62 X 92 in. New York, Academic Press, 1966. Price, $12.00. The most unusual feature of this compilation of papers on various particle physics topics is the edited transcript of discussion sessions led by some of the lecturers. On the whole the lectures are carefully prepared and are intended to expose and instruct rather than to astound and document; this format seems to have captured the best features of a summer school without losing the flavor of an informal conference. Physics of particles is a rapidly developing field and, despite the oft-repeated statement that not much progress has been achieved, there are always discoveries, consolidation and insight after each wave of enthusiastic hopping on a bandwagon. Towards the end of such a period (but before the disenchantment!) the reviews of the field often express the insights correctly, though perhaps in too enthusiastic terms. Recording these reviews is therefore of importance since physicists seem to develop selective amnesia about these persuasive views once the fashion changes. For higher symmetries 1965 seemed to be such a critical time; it is therefore good to see this collection compiled in 1965. By the nature of things some acquaintance with the current fads of particle physics is presupposed on the part of the reader in almost all the lectures. But the discussion sessions tend to help the beginner (as well as the expert).
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The lecture by Pais on "Higher Symmetries" contains a brief outline of the concepts and techniques of "higher" symmetry groups like SU(6), SU(6)w and SU(6, 6) and their application to particle phenomena. It states the successful correlation of data obtained using these groups but does not attempt an analysis of the consistency of the conceptual structure. Radicati, on the "Significance of Internal Symmetries," discusses the conceptual problems of dealing with the higher symmetries. The article by Bell on "Difficulties of Relativistic U(6)" is a careful presentation of the problems encountered in combining relativistic invariance with spin dependent higher symmetries. It is interesting to note that Bell avoids discussing the possibility of using the Foldy-Wouthuysen spin in this connection though it has already been discussed in this connection in the literature. Sharp treats "Deviation from Unitary Symmetry" and discusses methods of computing in a self-consistent fashion mass and coupling constant departures from unitary symmetric limit and, in particular, the plausibility of octet enhancement as a dynamical feature. Cabibbo deals with "Broken Symmetries and Sum Rules" and discusses dynamical computations of corrections to exact symmetry from postulates about the non-linear commutation relations between the local source operators for various particles and approximations to these results by using one-particle contributions only. The calculation of the correction to the Gamow-Teller beta decay coupling constant is discussed; it is interesting to note that in this fashion one reestablishes chirality invariance of the beta decay interaction. Prentki's contribution on "CP Violation" gives a general theoretical orientation to CP violation. This is taken up in much greater detail by Steinberger in his lectures on "CP Violation and K Decay." The excellent contribution of Franzini on "Proton-Antiproten Annihilations at Rest" gives a comprehensive review of the phenomenology of antiproten annihilation into various final states and the test of charge conjugation in the annihilation process. The other lectures include Snow on "Low Energy Hyperon-Proten Interactions," Focardi on "Strong Resonances," Meyer-Berkhart on
Journal of The Franklin Institute
Book Reviews "Current Experiments at DESY," LeeFranzini on the "Electron Spectrum from Muon Decay," and an excellent contribution on "Superconductors" by Cooper. The closing lecture "On the Privilege of Being a Scientist" by Weisskopf is delightful. E. C. G. SUDARSHAN
Physics Department Syracuse University Syracuse, New York ANTENNA ANALYSIS,by Edward A. Wolff. 514 pages, diagrams, illustrations, 6 X 9 in. New York, John Wiley & Sons, Inc., 1966. Price, $25.00. Antennas find use not only in the conventional areas of communication and navigation, but in somewhat newer fields such as radio astronomy, satellite tracking, and space communication and in the sophisticated military systems used for target detection and identification. Present day antennas are designed to operate from a low frequency of 10 KHz up to 100 GHz or higher. Thus, we may have wire antennas tens of miles in length or in contrast 200-ft. parabolic reflectors serving as antennas. In addition, antennas are found as horns, apertures and slots, as well as in the form of large phased arrays. According to the dust cover, more than one hundred antennas are treated in the present book. Antenna Analysis starts out on page one with Maxwell's equations. With these equations as a starting point and a knowledge of the boundary conditions as determined by antenna materials and geometry, and the use of standard mathematical techniques, expressions are developed for radiation and induction fields so that antenna performance may be calculated. The performance characteristics desired are impedance, bandwidth, gain, and directivity. To develop useful expressions giving these characteristics for the wide ranges of frequency and mechanical design one meets in present-day antennas is a formidable task and the author performs it well. The title of the book could equally well be "Antenna Analysis and Design" since the mathematical development is carried on, not as an exercise to illustrate field theory, but to a point at which expected antenna
Vol. 284, No. 1, J'uly 1967
performance is displayed in a family of graphs, in many instances, and in expressions useful in making numerical calculations, in other cases. The mathematical level is such as to make the book useful to graduate students in communication engineering or in physics as well as to the engineer in a research and development laboratory. In a book only 500 pages in length and with such wide coverage, the style is found to be terse, and explanations are short and to the point. Intermediate mathematical steps in a development are omitted unless they are essential to the argument or for clarity of exposition. Some topics are treated too briefly; for example, the rationale of methods used for reducing in an optimum fashion the level of side lobe radiation from an antenna without degrading its directivity. Here a reader will find it necessary to go to the original papers on the subject, but this task is facilitated since each chapter is followed by a selected and relevant, rather than exhaustive, set of references. The book is well written and readable and will be a valuable addition to the library of those engineers who require a knowledge of modern antennas and antenna systems. W. D. HERSHBEROER
Department of Engineering University of California Los Angeles, California THE EARTH TIDES, by Paul Melchior. 458 pages, diagrams, illustr. 6 × 9 in. New York, Pergamon Press, 1966. Price, $15.00. Several articles by Professor Melchior have appeared giving a general description of the earth tides, i.e., "Les Mardes Werrestres," Monographies, Observatoire Royal de Belgique, Vol. 4, 1954; "Ciel et Terre," Vol. 70, 1954; "Earth Tides:" Advances in Geophysics, Vol. 4, 1958; "Earth Tides:" Research in Geophysics, Vol. 2, 1964, and others. (Also R. Tomaschek, "Tides of the Solid Earth," Handbuch der Physik, Vol. 48, Geophysik II, 1957.) However, these are outside the pale of this new book under review. Authored by the Director of the International Centre for Earth Tides, Professor Melchior's The Earth Tides is the only work available in this specialized field. I t covers
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Weizmann Institute of Science Rehovoth, Israel RECENT DEVELOPMENTS IN PARTICLE SYMMETRIES, edited by A. Zichichi. 460 pages, diagrams, 62 X 92 in. New York, Academic Press, 1966. Price, $12.00. The most unusual feature of this compilation of papers on various particle physics topics is the edited transcript of discussion sessions led by some of the lecturers. On the whole the lectures are carefully prepared and are intended to expose and instruct rather than to astound and document; this format seems to have captured the best features of a summer school without losing the flavor of an informal conference. Physics of particles is a rapidly developing field and, despite the oft-repeated statement that not much progress has been achieved, there are always discoveries, consolidation and insight after each wave of enthusiastic hopping on a bandwagon. Towards the end of such a period (but before the disenchantment!) the reviews of the field often express the insights correctly, though perhaps in too enthusiastic terms. Recording these reviews is therefore of importance since physicists seem to develop selective amnesia about these persuasive views once the fashion changes. For higher symmetries 1965 seemed to be such a critical time; it is therefore good to see this collection compiled in 1965. By the nature of things some acquaintance with the current fads of particle physics is presupposed on the part of the reader in almost all the lectures. But the discussion sessions tend to help the beginner (as well as the expert).
70
The lecture by Pais on "Higher Symmetries" contains a brief outline of the concepts and techniques of "higher" symmetry groups like SU(6), SU(6)w and SU(6, 6) and their application to particle phenomena. It states the successful correlation of data obtained using these groups but does not attempt an analysis of the consistency of the conceptual structure. Radicati, on the "Significance of Internal Symmetries," discusses the conceptual problems of dealing with the higher symmetries. The article by Bell on "Difficulties of Relativistic U(6)" is a careful presentation of the problems encountered in combining relativistic invariance with spin dependent higher symmetries. It is interesting to note that Bell avoids discussing the possibility of using the Foldy-Wouthuysen spin in this connection though it has already been discussed in this connection in the literature. Sharp treats "Deviation from Unitary Symmetry" and discusses methods of computing in a self-consistent fashion mass and coupling constant departures from unitary symmetric limit and, in particular, the plausibility of octet enhancement as a dynamical feature. Cabibbo deals with "Broken Symmetries and Sum Rules" and discusses dynamical computations of corrections to exact symmetry from postulates about the non-linear commutation relations between the local source operators for various particles and approximations to these results by using one-particle contributions only. The calculation of the correction to the Gamow-Teller beta decay coupling constant is discussed; it is interesting to note that in this fashion one reestablishes chirality invariance of the beta decay interaction. Prentki's contribution on "CP Violation" gives a general theoretical orientation to CP violation. This is taken up in much greater detail by Steinberger in his lectures on "CP Violation and K Decay." The excellent contribution of Franzini on "Proton-Antiproten Annihilations at Rest" gives a comprehensive review of the phenomenology of antiproten annihilation into various final states and the test of charge conjugation in the annihilation process. The other lectures include Snow on "Low Energy Hyperon-Proten Interactions," Focardi on "Strong Resonances," Meyer-Berkhart on
Journal of The Franklin Institute
Book Reviews "Current Experiments at DESY," LeeFranzini on the "Electron Spectrum from Muon Decay," and an excellent contribution on "Superconductors" by Cooper. The closing lecture "On the Privilege of Being a Scientist" by Weisskopf is delightful. E. C. G. SUDARSHAN
Physics Department Syracuse University Syracuse, New York ANTENNA ANALYSIS,by Edward A. Wolff. 514 pages, diagrams, illustrations, 6 X 9 in. New York, John Wiley & Sons, Inc., 1966. Price, $25.00. Antennas find use not only in the conventional areas of communication and navigation, but in somewhat newer fields such as radio astronomy, satellite tracking, and space communication and in the sophisticated military systems used for target detection and identification. Present day antennas are designed to operate from a low frequency of 10 KHz up to 100 GHz or higher. Thus, we may have wire antennas tens of miles in length or in contrast 200-ft. parabolic reflectors serving as antennas. In addition, antennas are found as horns, apertures and slots, as well as in the form of large phased arrays. According to the dust cover, more than one hundred antennas are treated in the present book. Antenna Analysis starts out on page one with Maxwell's equations. With these equations as a starting point and a knowledge of the boundary conditions as determined by antenna materials and geometry, and the use of standard mathematical techniques, expressions are developed for radiation and induction fields so that antenna performance may be calculated. The performance characteristics desired are impedance, bandwidth, gain, and directivity. To develop useful expressions giving these characteristics for the wide ranges of frequency and mechanical design one meets in present-day antennas is a formidable task and the author performs it well. The title of the book could equally well be "Antenna Analysis and Design" since the mathematical development is carried on, not as an exercise to illustrate field theory, but to a point at which expected antenna
Vol. 284, No. 1, J'uly 1967
performance is displayed in a family of graphs, in many instances, and in expressions useful in making numerical calculations, in other cases. The mathematical level is such as to make the book useful to graduate students in communication engineering or in physics as well as to the engineer in a research and development laboratory. In a book only 500 pages in length and with such wide coverage, the style is found to be terse, and explanations are short and to the point. Intermediate mathematical steps in a development are omitted unless they are essential to the argument or for clarity of exposition. Some topics are treated too briefly; for example, the rationale of methods used for reducing in an optimum fashion the level of side lobe radiation from an antenna without degrading its directivity. Here a reader will find it necessary to go to the original papers on the subject, but this task is facilitated since each chapter is followed by a selected and relevant, rather than exhaustive, set of references. The book is well written and readable and will be a valuable addition to the library of those engineers who require a knowledge of modern antennas and antenna systems. W. D. HERSHBEROER
Department of Engineering University of California Los Angeles, California THE EARTH TIDES, by Paul Melchior. 458 pages, diagrams, illustr. 6 × 9 in. New York, Pergamon Press, 1966. Price, $15.00. Several articles by Professor Melchior have appeared giving a general description of the earth tides, i.e., "Les Mardes Werrestres," Monographies, Observatoire Royal de Belgique, Vol. 4, 1954; "Ciel et Terre," Vol. 70, 1954; "Earth Tides:" Advances in Geophysics, Vol. 4, 1958; "Earth Tides:" Research in Geophysics, Vol. 2, 1964, and others. (Also R. Tomaschek, "Tides of the Solid Earth," Handbuch der Physik, Vol. 48, Geophysik II, 1957.) However, these are outside the pale of this new book under review. Authored by the Director of the International Centre for Earth Tides, Professor Melchior's The Earth Tides is the only work available in this specialized field. I t covers
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