Symmetry and Modern Physics

The following sections are included:

• FOREWORD

• CONTENTS

I am delighted to have this opportunity to sing the praises of my old friend and colleague Frank Yang. The title of my talk is "A Conservative Revolutionary". The meaning of the title will become clear at the end of the talk…

The evolution of ideas which has led from the first proofs of the renormalizability of non-Abelian gauge theories, based on Slavnov–Taylor identities, to the modern proof based on the BRS symmetry and the master equation is briefly recalled. The content and consequences of the master equation are explained. This lecture has been delivered at the Symposium in Honor of Professor C. N. Yang, Stony Brook, May 21–22, 1999.

This is a talk given at the Symposium “Symmetries and Reflections”, dedicated to Prof. C. N. Yang's retirement. In this talk, I shall reflect on my personal interaction with Prof. Yang since my graduate career at SUNY Stony Brook, and his profound impact on my understanding of theoretical physics. I shall also review the SO(5) theory of high T_c superconductivity and show how my collaboration with Prof. Yang in 1990 led to the foundation of this idea.

The following sections are included:

• Introduction

• BEC and Condensed Matter Physics

• Spin-Polarized Hydrogen

• Laser Cooling

• The Effort at MIT 1990–1996
  • Improving laser cooling
  • Combining laser cooling and evaporative cooling
  • BEC in sodium
  • The cloverleaf trap
  • Interference between two condensates

• The Magic of Matter Waves
  • Amplification of atoms in a Bose–Einstein condensate
  • Observation of vortex lattices in Bose–Einstein condensates

• Outlook

• References

Recent observations and theoretical considerations have linked gamma-ray bursts with ultra-bright type Ibc supernovae (‘hypernovae’). We here work out a specific scenario for this connection. Based on earlier work, we argue that especially the longest bursts must be powered by the Blandford–Znajek mechanism of electromagnetic extraction of spin energy from a black hole. Such a mechanism requires a high angular momentum in the progenitor object. The observed association of gamma-ray bursts with type Ibc supernovae leads us to consider massive helium stars that form black holes at the end of their lives as progenitors. In our analysis we combine the numerical work of MacFadyen and Woosley with analytic calculations in Kerr geometry, to show that about 10⁵³ erg each are available to drive the fast GRB ejecta and the supernova. The GRB ejecta are driven by the power output through the open field lines threading the black hole, whereas the supernova can be powered both by the shocks driven into the envelope by the jet, and by the power delivered into the disk via field lines connecting the disk with the black hole. We also present a much simplified approximate derivation of these energetics.

Helium stars that leave massive black-hole remnants can only be made in fairly specific binary evolution scenarios, namely the kind that also leads to the formation of soft X-ray transients with black-hole primaries, or in very massive WNL stars. Since the binary progenitors will inevitably possess the high angular momentum we need, we propose a natural link between balck-hole transients and gamma-ray bursts. Recent observations of one such transient, GRO J1655-40/Nova Scorpii 1994, explicitly support this connection: its high space velocity indicates that substantial mass was ejected in the formation of the black hole, and the overabundance of α-nuclei, especially sulphur, indicates that the explosion energy was extreme, as in SN 1998bw/GRB 980425. Furthermore, X-ray studies of this object indicate that the black hole may still be spinning quite raidly, as expected in our model. We also show that the presence of a disk during the powering of the GRB and the explosion is required to deposit enough of the α nuclei on the companion. © 2000 Elsevier Science B.V. All rights reserved.

No abstract received.

Motivated by the recent experimental announcements for direct measurements of time-reversal non-invariance in the neutral kaon system, we make a comparative discussion of the CPLEAR and KTeV measurements. The most suitable way to consistently incorporate the mixing, the time evolution and the decays of kaons, is to describe the neutral kaon system as a system with a non-Hermitean Hamiltonian. In this framework, the physical (decaying) incoming and outgoing states are distinct and belong to dual spaces. Moreover, since they are eigenstates of the full Hamiltonian, they never oscillate. This is directly manifest in the orthogonality conditions of the physical states, which entirely determine the evolution of the kaon system. Along these lines we conclude: CPLEAR studies oscillations, a process where initial and final states can be reversed, the CPLEAR asymmetry being an effect directly related to the definition of time-reversal. Conclusively, CPLEAR provides a direct measurement of -violation without any assumption either on unitarity or on -invariance. The KTeV experiment studies in particular the process K_L → π⁺π⁻e⁺e⁻, where they measure a -odd effect. However, using unitarity together with estimates of the final state interactions, it should be possible to determine whether this effect can be identified with a genuine -reversal violation.

It is a great honor to be invited for this important occasion. The first time I had met Prof. Yang was in the fall term of 1971 when he gave a series of public lectures at Stony Brook. I was deeply impressed by the intuitive power of physics as described by the great master. In the following years, I saw the impact of Yang–Mills theory on mathematics. It was exciting for a geometer to study the effect of physical intuition in our field and what we could do for physics in return. I spent the next thirty years exploring such an interaction. It was a fruitful research: from general relativity, to gauge theory and to string theory. The influence of Prof. Yang is very deep and I am grateful to him. In this note, I will explain such a personal experience. The choice of topic is therefore rather subjective…

We present a simple lecture covering 35 years of research on exactly solvable one-dimensional quantum many-body systems — the Bethe's Ansatz — its generalizations and related developments. Although the selection of topics is my own, the work has been done by several others. Further, the contributions have built on one another in such a way that — to be honest — it is difficult to imagine one bit without the others. So, please see this talk as an appreciation of a long and fruitful history of cooperation, beginning with Bethe, and spanning generations.

Electron interference has been investigated at an industrial laboratory of Hitachi, Ltd. for the past 30 years thanks to the encouragement and support of C. N. Yang, who retired from the State University of New York in 1999. This paper reports here fundamentals and applications of electron interference experiments we have carried out including our relation to C. N. Yang, and is based on a talk made in honor of him at the “Symmetries and Reflections” Symposium held at Stony Brook in May 1999.

The following sections are included:

• Introduction

• Proton Spin Dynamics

• Resonances
  • Single resonance
  • Passage through resonance
  • Mitigation
  • AGS resonances
  • RHIC
  • HERA

In this paper we describe the basic principles of the high gain free electron lasers (FEL) and the research and development towards X-ray FEL. We discuss several different schemes of seeded single pass FEL to improve the temporal coherence, and the advantages and limitations of these schemes. We discuss the High Gain Harmonic Generation (HGHG) experiment in the infrared region, and the recent Deep Ultraviolet FEL experiment using the HGHG method at Brookhaven National Laboratory.

The Yang–Mills theory is the most important development in physics in the second half of this century. Some of the highlights are briefly summarized.

After noting that the Standard Model could never have been discovered without the crucial insights that lead Frank Yang to writing his seminal 1954 paper with R. Mills, we continue to marvel at the rich amount of information that appears to be hidden in this model. The specific group structure of the local gauge transformations, the representations of these groups found in the fermionic and the Higgs sector, all seem to be telling us something about Nature at ultrashort distance scales. Many researchers are trying to embed the observed system in a supersymmetric scheme. Here, we suggest a more ambitious attempt: to see if one can find some deterministic underlying theory. An attempt to pioneer such an approach is explained.

After Dalitz¹ deduced from a detailed analysis of experimental data that the decay products of the apparently "like" mesons θ and τ, into 2π and 3π, respectively, form states of opposite parity, attempts were made to find differences in some of the properties of θ and τ before decay, by measuring the mass, lifetime, and scattering for each. Within the accuracy attained no differences were found, but from such experiments a definitive proof of identity cannot be reached, even with "asymptotically" improved acuracy. Since identity would have implied the nonconservation of parity, contradicting an important symmetry principle, thus the θ−τ puzzle was born!…

Note from Publisher: This article contains the abstract and references only.

Tonight we celebrate one milestone in a distinguished career, and also an ongoing constellation of achievements that have touched, in one way or another, every person in this room…

The following sections are included:

• PROGRAM

• PHOTOS

• PARTICIPANTS

• Scientific and Related Works of Chen Ning Yang