Introduction

Access to information is fundamental to all areas of administrative law. Indeed, the very early origins of prerogative writs have been characterised in terms of information access: ‘certiorari was essentially a royal demand for information’. The relationship between the citizen and the state is one of unequal power that modern administrative law helps to redress. Access to information is crucial to that process. The duty to disclose adverse information is central to the procedural fairness that government decision-makers must accord to persons whose interests are directly affected by their actions. Once a decision has been made, providing reasons is essential if affected people are to properly understand whether the decision may be susceptible to administrative or judicial review.

Public access to information is also central to the administrative law goals of executive accountability and improving the quality, efficiency and effectiveness of government decision-making. In modern democracies, governments are obliged to disclose information in a wide range of circumstances, including: answering parliamentary questions; disclosing evidence to independent inquiries and to courts; and many official reporting obligations. This chapter will focus upon one particular system of information disclosure: the rights of citizens to access government documents granted by Commonwealth and State freedom of information statutes. It will provide an overview of those statutes and their recent reforms, and identify some key areas of ongoing concern.

Only a few elementary particles are stable: the electron, the proton, the neutrinos and the photon. Many more are unstable. The particles that decay by weak interactions live long enough to travel macroscopic distances between their production and decay points. Therefore, we can detect them by observing their tracks or measuring their time of flight. Distances range from a fraction of millimetre to several metres, depending on their lifetime and energy. In this chapter, we shall study the simplest properties of these particles and discuss the corresponding experimental discoveries. In the next chapter we shall present to the reader the symmetry properties of the interactions and the corresponding selection rules, and in Chapter 4 we shall discuss the hadronic resonances, i.e. the particles that decay via strong interactions with lifetimes too short to allow them to travel over observable distances.

The development of experimental sciences is never linear, rather it follows complicated paths reaching partial truths, making errors that are later corrected by new experiments, often with completely unexpected results, and gradually reaching the correct conclusions. The study of at least a few aspects of such a development requires some effort but it is worth it to gain a deeper understanding of the resulting physical laws. This is why in this chapter we shall initially follow a historical approach.

We shall start by recalling the Yukawa assumption of a meson, the pion, as the mediator of the nuclear forces.

In the previous chapters we have learnt the properties of the elementary particles, a term that includes also the hadrons, which, as we have seen, are composed of smaller structures, the quarks and the gluons.

Now, starting with this chapter, we shall discuss the electromagnetic, strong and weak interactions of the leptons and the quarks, and finally their unification in the Standard Model. All of them are quantum field theories, for all of them the interaction Lagrangian is invariant under a local gauge symmetry, corresponding to different symmetry groups.

First, consider quantum electrodynamics, which corresponds to classic electrodynamics, namely the Maxwell equations. It was the first to be historically developed and the one with the simplest structure, corresponding to the simplest gauge group, namely U(I) We shall start by recalling the gauge invariance of the Maxwell equations and its strict connection to the conservation of the electric charge. These concepts are present in quantum field theories too, in which they become even more fundamental, because they determine the form of the interaction itself.

The fundamental experiment showing that non-relativistic quantum mechanics was insufficient to describe Nature was done by Lamb and Retherford in 1947. This masterpiece of atomic experimental physics is described in Section 5.2. We shall see that, in quantum field theory, it is not only the photons that are quanta of a field but also the charged particles, like the electrons and positrons.

This book is mainly meant to be a presentation of subnuclear physics, at an introductory level, for undergraduate physics students, not necessarily for those specialising in the field. The reader is assumed to have already taken, at an introductory level, nuclear physics, special relativity and quantum mechanics, including the Dirac equation. Knowledge of angular momentum, its composition rules and the underlying group theoretical concepts is also assumed at a working level. No prior knowledge of elementary particles or of quantum field theories is assumed.

The Standard Model is the theory of the fundamental constituents of matter and of the fundamental interactions (excluding gravitation). A deep understanding of the ‘gauge’ quantum field theories that are the theoretical building blocks of this model requires skills that the readers are not assumed to have. However, I believe it to be possible to convey the basic physics elements and their beauty even at an elementary level. ‘ Elementary’ means that only knowledge of elementary concepts (in relativistic quantum mechanics) is assumed. However it does not mean a superficial discussion. In particular, I have tried not to cut corners and I have avoided hiding difficulties, whenever was the case. I have included only well established elements with the exception of the final chapter, in which I survey the main challenges of the present experimental frontier.

The text is designed to contain the material that may be accommodated in a typical undergraduate course. This condition forces the author to hard, and sometimes difficult, choices.

Introduction

In 2008 the now late Professor Michael Taggart argued that Australian administrative law was in many ways ‘exceptional’ amongst common law jurisdictions. He was right to suggest that Australian public law, especially perhaps administrative law, ‘stands apart’ from other common law jurisdictions. Indeed that trend has continued, and it seems that Australian administrative law is becoming increasingly distant from its counterparts in the United Kingdom, Canada and New Zealand. Taggart and others have noted that much of what is exceptional about Australian public law can be traced to our written constitution. The Constitution and its implications are now the dominant force shaping Australian administrative law at the federal and state levels. The separation of powers doctrine implied from the division of the Constitution into three chapters, and the express protection in s 75(v) of the High Court’s original jurisdiction to remedy unlawful administrative action, have been instrumental in driving the direction of Australian administrative law.

The growing influence of the Constitution has diverted attention from our unique statutory framework of administrative law, which also sets Australia apart from most other jurisdictions. The reforms made in Australia during the 1970s and 1980s, resulting in what is widely known as the ‘new administrative law’, developed a modern and ‘comprehensive system of administrative law’ which sought to shift focus from the courts as the central institution responsible for executive accountability, by creating several new systems and agencies of administrative review.

The Standard Model describes the word at elementary level with a few elements, three families of spin 1/2 fermions – the quarks and the leptons – the vector bosons mediators of the strong and electro-weak interactions – one photon, three weak bosons and eight gluons – and one scalar boson – the H at the origin of the vector bosons and elementary fermion masses. In this book we have been faithful to the rule of sticking to the facts, namely to experimentally confirmed theoretical statements. Let us just mention in passing that from time to time experiments report ‘evidence’ of violations of the Standard Model predictions, which, however, are not statistically significant. Indeed, misleading fluctuations of the background can always happen. Consequently, as a rule of thumb, nothing at less than 3 or 4 standard deviations should be considered as evidence.

All of that is not enough and we know that the Standard Model cannot be the final theory, because of the observation of facts that the Model is not able to explain and also for ‘aesthetic’ reasons. We shall briefly mention these problems.

Neutrino mass

As we discussed in Chapter 10, physics beyond the Standard Model has been firmly established with neutrino oscillations and flavour change. A possible way to extend the Standard Model mechanism to give mass to neutrinos is by assuming the existence of right neutrinos, as for the other leptons.

Introduction

Just as governments are obliged to allow access to information on request, they are also required to maintain the privacy of the personal information that they hold. Privacy is the neglected aspect of information management because it is not well understood. This is in part because privacy as a concept is difficult to understand and partly because the regulatory framework which regulates it is complex.

This chapter is concerned with the privacy of information that is handled by government agencies. Information privacy – or data protection, as it is more commonly described in Europe – is frequently confused with related concepts such as secrecy and confidentiality. However, it differs from them in important respects. Privacy may require secrecy as an aspect of information security, but it is much broader and more flexible in its scope. It may also overlap with confidentiality where personal information is received in a context which imposes an obligation to treat it as confidential, but it extends much more broadly. Its key focus is on the ability of individuals to exercise control over the handling of their identifiable personal information. It therefore has a critical role to play in establishing appropriate boundaries between citizen and government.

Introduction

Security concerns raise troubling rule of law questions about the weighing of competing public interests in national security, fairness to affected individuals, the accountability of administrative decision-makers, and public confidence in the openness of justice before the courts. Such concerns habitually emerge in times of crisis, such as during the world wars and the Cold War, and the pall of suspicion often falls most heavily on ‘outsiders’, whether Germans and Japanese, communists or terrorists. Legal concerns about security were reignited by the heightened security environment after the 11 September 2001 terrorist attacks and recurring political preoccupations with strong ‘border protection’.

Many legal doctrines, principles and procedures may apply where national security is raised in administrative decision-making or judicial review proceedings. The content or quality of procedural fairness at common law or under statute may vary. Special statutory procedures may govern the handling of security-sensitive information. The availability and nature of merits review can be affected and non-binding reviewers may displace binding tribunals. Public interest immunity may be invoked to preclude the admissibility of otherwise relevant evidence. The degree of scrutiny brought to bear by judges may diminish out of deference to executive expertise in making security judgements.

The non-stable particles we have discussed up to now decay by weak or electromagnetic interactions. The distance between their production and decay points is long enough to be observable. If the mass of a hadron is large enough, final states that can be reached by strong interaction, i.e. without violating any selection rule, become accessible to its decay. Therefore, the lifetime is extremely short, of the order of an yoctosecond (10−24 s). These hadrons decay, from the point of view of an observer, exactly where they were born. To fix the orders of magnitude, consider such a particle produced in the laboratory reference frame with a Lorentz factor as large as γ = 300. In a lifetime, it will travel one femtometre (1 fm).

These extremely unstable hadrons can be observed as ‘resonances’ in two basic ways: in the process of ‘formation’, in the energy dependence of a cross-section, or in the ‘production’ process, as a maximum in the invariant mass distribution of a subset of particles in the final states of a reaction. We shall discuss that, after having recalled the features of the resonance phenomenon already present in classical mechanics and electromagnetism.

Such hadrons, baryons and mesons were discovered in a rapidly increasing number, in the 1950s and early 1960s in experiments at proton accelerators by mainly using bubble chambers as detectors. Their quantum numbers, spin, parity and isotopic spin were measured.

Introduction

The integrity branch of government consists of those permanent institutions, established with a degree of political independence under a constitution or by statute, whose function is solely or primarily to ensure that other governmental institutions and officials exercise the powers conferred on them for the purposes for which they were conferred, and in the manner expected of them, consistent with both the legal and wider precepts of integrity and accountability which are increasingly recognised as fundamental to good governance in modern liberal democracies.

Recognising the reality and potential of the integrity branch is especially important to administrative law. As the ‘law of public accountability’, administrative law does not operate in a legal vacuum in the same way as other specialist areas of law. Administrative lawyers know that the most effective forms of relief for citizens aggrieved by official decision-making often lie not in remedies ‘at law’, but in the administrative investigation and resolution of complaints by an ombudsman, or merits review by a tribunal. Where legal questions do become central to a dispute or action, they often revolve around questions of the powers that were (or are) available to decision-makers and how those powers should be exercised in accordance with constitutional or statutory limits, conditions or responsibilities. Ever since Ian Thynne and Jack Goldring’s seminal work, Accountability and Control: Government Officials and the Exercise of Power, it has been clear in Australia that modern systems of public integrity encompass mechanisms of constitutional and administrative law, public administration and management, and financial accountability. As if these did not together define a big enough field, integrity systems also encompass the processes used to regulate the personal integrity, conduct and misconduct of individuals, right through to the criminal law.

In this chapter we begin the study of weak interactions, continuing in Chapter 8 and 9, in which we shall see how electromagnetic and weak interactions are unified. There are two types of fermionic currents in weak interactions: charged currents (CC), mediated by the charged vector bosons W+ and W−, and neutral currents (NC) mediated by the Z0. In the scattering or decay amplitude the vector bosons propagate, as in QED and QCD, between vertices. However, unlike photons and gluons, the weak vector bosons are massive, with masses of the order of 100 GeV. Consequently, at low energies the two vertices appear merged in one and the interaction is point-like.

We shall start by studying the weak decays of the particles. These are CC low-energy phenomena and are described, with a very good approximation, by the Fermi point-like interaction. The interaction amplitudes are universal in the sense that are proportional to the same, very important, quantity, the Fermi constant.

We shall see that parity and particle–antiparticle conjugation are not conserved, rather are maximally violated in CC weak interactions, as shown by the beautiful experiment of C. S. Wu and collaborators. The consequence is that the bi-spinor fields in the CC weak interactions are eigenstates of the Dirac matrix γ5 of negative eigenvalue. We say that they have negative chirality or that they are left. We shall carefully elucidate the delicate issue of the difference between chirality and helicity, two concepts that are often confused.