100 Years of Subatomic Physics

The following sections are included:

• Preface

• Contents

The following sections are included:

• Theoretical and Experimental Barriers

• Obstacles to a Comprehensive Field Theory

• The Standard Model

• Not the Last Word

The following sections are included:

• Introduction

• Radioactivity
  • Alpha decays and the strong force
  • Gamma decays and the electromagnetic interaction
  • Beta decays and the weak interaction
  • Neutrons and fission

• Nuclear Forces
  • Charge independence

• Nuclear Reactions
  • Compound-nucleus and direct reactions
  • Optical potential
  • Resonances

• Early Nuclear Structure Models
  • The liquid drop model
  • The shell model
  • Collective models

• Outlook

• Acknowledgments

• References

The following sections are included:

• Introduction

• A Bit of History

• Present Day Experimental Research in Nuclear Masses

• Calculation of Nuclear Masses

• Extended Liquid Drop Models

• Microscopic Approaches

• Local Mass Relations

• References

Nuclei are very complex systems. Even without going to the level of quarks and gluons, they are systems of strongly interacting protons and neutrons (nucleons). Their number is usually higher than in a few-body system. It is also sufficiently small and cannot be treated statistically. In spite of their complexity, nuclei exhibit some simple regularities, which may be expressed by simple models. The most important regularity is the apparent independent motion of nucleons. The success of the shell model in describing many aspects of nuclear physics is based on this regularity. The shell structure leads to many symmetries which are briefly considered in this review. Only those that are associated with the spherical shell model will be presented. Nuclei that exhibit collective phenomena, like rotational spectra, are well described by a deformed potential well. They will not be discussed here. The limited space does not allow derivation of many results and they will simply be quoted. This allows a rather concise overview of some important symmetries and dynamical symmetries of nuclear states…

Nuclear fission is not only a spectacular subatomic process that continues to pose exciting intellectual challenges, it also plays a profound role in society. This chapter describes the basic features of fission and illustrates current advances in theory, phenomenology, and experiment that keep the field thriving…

Nuclear physics tests of parity- and time-reversal invariance have both shaped the development of the Standard Model and provided key tests of its predictions. These studies now provide vital input in the search for physics beyond the Standard Model. We give a brief review of a few key experimental and theoretical developments in the history of this sub-field of nuclear physics as well as a short outlook, focusing on weak decays, parity-violation in electron scattering, and searches for permanent electric dipole moments of the neutron and neutral atoms…

I review the development of high energy nuclear physics, in particular the attempts to make new forms of matter in hadronic collisions. I begin with early experimental work done at the Bevelac, the AGS and the SPS. Early theoretical work concentrated on understanding properties of quark and gluonic matter at high temperature and density, the Quark Gluon Plama (QGP), particularly using the methods of lattice gauge theory. Recent theoretical work has involved attempts to more quantitatively describe data coming from experiments at RHIC and LHC. In addition, new forms of matter have been proposed to describe the early times in hadronic collisions. The Color Glass Condensate (CGC) is the high density gluonic matter that initially composes colliding high energy nuclei. The Glasma is highly coherent color electric and color magnetic fields radiating gluons that eventually thermalize. Methods derivative of strongly interacting gauge theory (AdSCFT Correspondence) have been employed to qualitatively understand finite temperature QCD when the intrinsic strength of interactions is strong. The RHIC and LHC experiments provide compelling experimental data to establish that the matter produced in ultra-relativistic heavy is a strongly interacting Quark Gluon Plasma (sQGP). To what degree, in my opinion, the sQGP is a thermally equilibrated Quark Gluon Plasma, or a Glasma is not yet determined…

These are some personal thoughts on the role of chiral symmetry in subatomic physics…

The recent availability of radioactive beams has opened up a new era in nuclear physics. The interactions and structure of exotic nuclei close to the drip lines have been studied extensively worldwide, and it has been revealed that unstable nuclei, having weakly bound nucleons, exhibit characteristic features such as a halo structure and a soft dipole excitation. We here review the developments of the physics of unstable nuclei in the past few decades. The topics discussed in this chapter include the halo and skin structures, the Coulomb breakup, the dineutron correlation, the pair transfer reactions, the two-nucleon radioactivity, the appearance of new magic numbers, and the pygmy dipole resonances…

The following sections are included:

• Introduction

• The Pathfinders

• The “Production” Electron–Positron Machines

• Hadron Colliders

• Conclusion

The following sections are included:

• Introduction

• Elementary Concepts of 4π Detection

• Searching for the Higgs Boson

• Photons and Electromagnetic Calorimeters

• Electrons and Tracking Systems

• Hadron Calorimeters

• Muon Spectrometers

• Jets, Heavy Flavor, and Vertex Detectors

• Tau-Leptons and Missing Energy

• Trigger, Data-Acquisition, and Computing

• Global Detector Assembly

• Future Developments

• References

This chapter tells the story of several decades of experimental physics done deep underground with huge detectors. Not for the first time in the history of science, the most exciting signals were not the ones originally sought. Large underground detectors were originally designed and built to search for the decay of the proton, which was predicted by Grand Unified Theories (GUTs). Later, these same detectors studied solar, supernova, and atmospheric neutrinos. The unambiguous discovery of neutrino mass and oscillations was a highlight of the end of last century; the solution to the solar neutrino problem was a highlight of the beginning of this century. Current-generation detectors acting as targets for reactor and beam neutrinos have been steadily improving our understanding of neutrinos. And the story is not over — the original quest for proton decay has not yet been fulfilled, neutrinos have not yet yielded all their secrets, and more surprises may be in store…

An essential element of the development of the strong interaction component of the Standard Model of particle physics, QCD, has been the evolving understanding of the “jets” of particles that appear in the final states of high energy particle collisions. In this chapter we provide a historical outline of those developments…

We review the evolution of the studies on diffractive processes in the strong interaction over the last 60 years. First, we briefly outline the early developments of the theory based on analyticity and unitarity of the S-matrix, including the derivation and exploration of Regge trajectories and related moving cuts. Special attention is paid to the concept of the Pomeron trajectory introduced for the description of total, elastic and diffractive cross-sections at high energies and to the emergence of the dynamics of multi-Pomeron interactions. The role of large longitudinal distances and color coherent phenomena for the understanding of inelastic diffraction in hadron–hadron scattering and deep inelastic scattering is emphasized. The connection of these phenomena to the cancellation of the contribution of the Glauber approximation in hadron–nucleus collisions and to the understanding of the Gribov–Glauber approximation is explained. The presence of different scales in perturbative QCD due to masses of heavy quarks has led to the emergence of numerous new phenomena including non-universality of the slopes of Regge trajectories made of light and heavy quarks and non-universal energy dependence of elastic cross-sections. The application of perturbative QCD techniques allowed us to calculate from first principles the interaction of small-transverse-size color singlets with hadrons leading to the development of the quantitative theory of hard exclusive reactions and to the successful prediction of many regularities in hard large mass diffraction. It also led to the prediction of the phenomenon of complete transparency of nuclear matter in QCD in special processes. The conflict of perturbative QCD with probability conservation for high energy processes of virtual photon–nucleon scattering is explained. Some properties of the new QCD regime are outlined…

This chapter provides a brief overview for non-specialists of some of the highlights in the development of the theory of weak interactions during the past century…

The following sections are included:

• Neutrino Interactions

• Neutrino Oscillations

• Neutrino Masses and Mixings

• Neutrino Astronomy

• Acknowledgment

A simple introduction of renormalization in quantum field theory is discussed. Explanation of concepts is emphasized instead of the technical details…

Most of the mass of everyday objects resides in atomic nuclei; the total of the electrons’ mass adds up to less than one part in a thousand. The nuclei are composed of nucleons — protons and neutrons — whose nuclear binding energy, though tremendous on a human scale, is small compared to their rest energy. The nucleons are, in turn, composites of massless gluons and nearly massless quarks. It is the energy of these confined objects, via M = E/c², that is responsible for everyday mass. This chapter discusses the physics of this mechanism and the role of lattice gauge theory in establishing its connection to quantum chromodynamics…

This chapter presents an overview of string theory and M-theory. It introduces the basic concepts together with a brief history of how the subject was developed. Although string theory was initially viewed as a radical alternative to quantum field theory, more recent discoveries make it clear that it is actually the logical completion of quantum field theory, and therefore it is not radical at all. The chapter also describes various approaches that are used in the ongoing attempts to account for particle physics phenomenology, and it addresses the question of how predictive the theory is likely to be…