bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum evolution: From particles to non-relativistic fields
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
Chapter 4 has introduced the functional integral representation of the quantum statistical operators and thus, formally, evolution in imaginary or Euclidean time. By contrast, to calculate the evolution operator and the scattering S-matrix elements, quantities relevant to particle physics, it is necessary to make a continuation from imaginary to real time. However, the representation of the S-matrix follows from additional considerations. To illustrate the power of the formalism, we show how to recover the perturbative expansion of the scattering amplitude, some semi-classical approximations, and the eikonal approximation. When the asymptotic states at large time are eigenstates of the harmonic oscillator, instead of free particles, the holomorphic formalism becomes useful. A simple generalization of the path integral of Chapter 4 leads to the corresponding path integral representation of the S-matrix. In the case of the Bose gas, the evolution operator is then given by a holomorphic field integral. A parallel formalism leads to an analogous representation for the evolution operator of a system of non-relativistic fermions.
Perturbative quantum field theory (QFT): Algebraic methods
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
This chapter discusses systematically the algebraic properties of perturbation theory in the example of a local, relativistic scalar quantum field theory (QFT). Although only scalar fields are considered, many results can be easily generalized to relativistic fermions. The Euclidean formulation of QFT, based on the density matrix at thermal equilibrium, is studied, mainly in the simpler zero-temperature limit, where all d coordinates, Euclidean time and space, can be treated symmetrically. The discussion is based on field integrals, which define a functional measure. The corresponding expectation values of product of fields called correlation functions are analytic continuations to imaginary (Euclidean) time of the vacuum expectation values of time-ordered products of field operators. They have also an interpretation as correlation functions in some models of classical statistical physics, in continuum formulations or, at equal time, of finite temperature QFT. The field integral, corresponding to an action to which a term linear in the field coupled to an external source J has been added, defines a generating functional Z(J) of field correlation functions. The functional W(J) = ln Z(J) is the generating functional of connected correlation functions, to which contribute only connected Feynman diagrams. In a local field theory connected correlation functions, as a consequence of locality, have cluster properties. The Legendre transform Γ(φ) [N1]of W(J) is the generating functional of vertex functions. To vertex functions contribute only one-line irreducible Feynman diagrams, also called one-particle irreducible (1PI).
Ultraviolet divergences: Effective field theory (EFT)
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
Only local relativistic quantum field theories (QFT) are considered: the action that appears in the field integral is the integral of a classical Lagrangian density, function of fields and their derivatives (taken at the same point). Physical quantities can be calculated as power series in the various interactions. As a consequence of locality, infinities appear in perturbative calculations, due to short-distance singularities, or after Fourier transformation, to integrals diverging at large momenta: one speaks of ultraviolet (UV) divergences. These divergences are peculiar to local QFT: in contrast to classical mechanics or non-relativistic quantum mechanics (QM) with a finite number of particles, a straightforward construction of a QFT of point-like objects with contact interactions is impossible. A local QFT, in a straightforward formulation, is an incomplete theory. It is an effective theory, which eventually (perhaps at the Planck's scale?), to be embedded in some non-local theory, which renders the full theory finite, but where the non-local effects affect only short-distance properties (an operation sometimes called UV completion). The impossibility to define a QFT without an explicit reference to an external short scale is an indication of a non-decoupling between short- and long-distance physics. The forms of divergences are investigated to all orders in perturbation theory using power counting arguments.
Dimensional continuation, regularization, minimal subtraction (MS). Renormalization group (RG) functions
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
In this chapter, the notions of dimensional continuation and dimensional regularization are introduced, by defining a continuation of Feynman diagrams to analytic functions of the space dimension. Dimensional continuation, which is essential for generating Wilson–Fisher's famous ϵexpansion in the theory of critical phenomena, and dimensional regularization seem to have no meaning outside the perturbative expansion of quantum field theory (QFT). Dimensional regularization is a powerful regularization technique, which is often used, when applicable because it leads to much simpler perturbative calculations. Dimensional regularization performs a partial renormalization, cancelling what would show up as power-law divergences in momentum or lattice regularization. In particular it cancels the commutator of quantum operators in local QFTs. These cancellations may be convenient but may also, occasionally, remove divergences that have an important physical meaning. It is not applicable when some essential property of the field theory is specific to the initial dimension. For example, in even space dimensions, the relation between γS (identical to γ5 in four dimensions) and the other γ matrices involving the completely antisymmetric tensor ϵμ1···μd, may be needed in theories violating parity symmetry. Its use requires some care in massless theories because its rules may lead to unwanted cancellations between ultraviolet and infrared logarithmic divergences. Explicit calculations at two-loop order in a scalar QFT with a general four-field interaction are performed.
The non-linear σ-model near two dimensions: Phase structure
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
This chapter is devoted to the study of the non-linear σ-model, a quantum field theory (QFT) where the (scalar) field is an N-component vector of fixed length, mostly in dimensions close to 2. The model possesses a global, non-linearly realized symmetry, O(N) symmetry: under a group transformation, the transformed field is a non-linear function of the field itself. The non-linear σ-model belongs to a class of models constructed on special homogeneous spaces, symmetric spaces that, as Riemannian manifolds, admit a unique metric. Unlike what happens in a (ϕ2)2 -like field theory with the same symmetry, in the non-linear σ-model, in the tree approximation, the O(N) symmetry is always spontaneously broken: the action describes the interactions of (N−1) massless fields, the Goldstone modes. Since the fields are massless, in two dimensions infrared divergences appear in the perturbative expansion and an infrared regulator is required. To understand the phase structure beyond leading order, a renormalization group (RG) analysis is necessary. This requires understanding how the model renormalizes. Power counting shows that the model is renormalizable in two dimensions. Since the field then is dimensionless, although the degree of divergence of Feynman diagrams is bounded, an infinite number of counterterms is generated, because all correlation functions are divergent. A quadratic master equation satisfied by the generating functional of vertex functions is derived, which makes it possible to prove that the coefficients of all counterterms are related, and that the renormalized theory depends only on two parameters.
Quantum field theory (QFT) at finite temperature: Equilibrium properties
Authors: Zinn-Justin Jean 
Published: June 2021

Abstract
Some equilibrium properties in statistical quantum field theory (QFT), that is, relativistic QFT at finite temperature are reviewed. Study of QFT at finite temperature is motivated by cosmological problems, high energy heavy ion collisions, and speculations about possible phase transitions, also searched for in numerical simulations. In particular, the situation of finite temperature phase transitions, or the limit of high temperature (an ultra-relativistic limit where the temperature is much larger than the physical masses of particles) are discussed. The concept of dimensional reduction emerges, in many cases, statistical properties of finite-temperature QFT in (1, d − 1) dimensions can be described by an effective classical statistical field theory in (d − 1) dimensions. Dimensional reduction generalizes a property already observed in the non-relativistic example of the Bose gas, and indicates that quantum effects are less important at high temperature. The corresponding technical tools are a mode-expansion of fields in the Euclidean time variable, singling out the zero modes of boson fields, followed by a local expansion of the resulting (d − 1)-dimensional effective field theory (EFT). Additional physical intuition about QFT at finite temperature in (1, d−1) dimensions can be gained by considering it as a classical statistical field theory in d dimensions, with finite size in one dimension. This identification makes an analysis of finite temperature QFT in terms of the renormalization group (RG), and the theory of finite-size effects of the classical theory, possible. These ideas are illustrated with several simple examples, the φ4 field theory, the non-linear σ-model, the Gross–Neveu model and some gauge theories.
Experimental Methods
Authors: Kresin Vladimir Z. , Ovchinnikov Sergei G. , Wolf Stuart A. 
Published: June 2021

Abstract
In this chapter, several of the most important experimental techniques are described. These have been used to probe the most fundamental properties of the superconducting state: the energy gap and the pairing interaction. These methods have played a crucial role in validating the mechanism of superconductivity in conventional superconductors and are key to a fundamental understanding of superconductivity in more recently discovered novel superconductors like cuprates, Fe-based superconductors, and so on. The techniques that are described are all spectroscopic: tunnelling of quasiparticles through an insulating barrier or through a point contact ,Josephson tunnelling, the interaction of photons with a superconducting film or surface, the attenuation of ultrasonic waves,, the relaxation and/or resonance of muons interacting with a superconducting compound, and resonant inelastic X-ray scattering (RIXS). High-pressure techniques and the preparation of thin films and junctions are described. In addition, a state-of-the-art experimental procedure that enables the observation of the Little mechanism is discussed.
Materials I: High-Tc Copper Oxides
Authors: Kresin Vladimir Z. , Ovchinnikov Sergei G. , Wolf Stuart A. 
Published: June 2021

Abstract
This chapter focuses on the cuprates, which are uniquely interesting superconducting compounds due to their high Tc, peculiar properties, and potential for applications. The history of the discovery of this very unusual class of superconductors is described, together with the properties and key theoretical concepts that can be used to understand their superconducting and normal behaviours. This chapter contains a description of some very key aspects of these materials: their very unusual phase diagram, where doping takes the compounds from antiferromagnetic insulators to high-temperature superconductors and finally to metallic conductivity; their very anomalous upper critical field Hc2; the symmetry of their order parameter; and the unusual isotope effect on Tc and penetration depth. There are two main approaches to the issue of the origin of high Tc in the cuprates: the phonon mechanism, with the strong impact of the polaronic effect, and a mechanism based on strong correlation effects.
The Route to the East
Authors: McAleer John 
Published: June 2021

Abstract
The islands of the mid-Atlantic played crucial roles in forging and maintaining Britain’s empire in the age of sail. They were strategic hubs defending trade routes and offering benefits to military forces. Many provided opportunities to resupply ships and to recuperate men. For seafarers, Atlantic islands also acted as psychological and cultural acclimatisation stations. Finally, these islands offered opportunities for men of science to collect, to hypothesize, and to experiment. Taking these themes as its basis, this chapter demonstrates how Atlantic islands acted as ‘gateways’ to British imperial activities elsewhere in the world. By focusing on the part played by mid-Atlantic islands, it argues that the East India Company’s empire of trade, the Enlightenment empire of science, and the British Empire of colonies and fortified factories overlapped, coincided, and coexisted in the islands of the Atlantic. Ultimately, the islands of the mid-Atlantic were fulcra around which Britain’s global world turned.
Islands of Incarceration and Empire Building in Colonial Australia
Authors: Roscoe Katherine 
Published: June 2021

Abstract
This chapter examines the key roles played by Australia’s offshore prison islands in the British Empire. It begins with the arrival of the First Fleet at Botany Bay in 1788, and ends in 1868, when the last Antipodean colony, Western Australia, stopped accepting convicts. It builds on the volume’s focus on islands as integral to the imperial project, but foregrounds the specific role played by prison labourers. Paradoxically, islands embodied both isolation and connection, prison islands especially so. The British government strategically deployed isolation, by exiling populations resistant to frontier expansion to islands, and connection, by exploiting convict labour on islands to tap into imperial networks of communication and commerce. The Australian colonies were Britain’s most remote imperial possessions, with sailing ships journeying several months to reach their shores. The position of islands enabled them to act as prisons, trading outposts, Aboriginal ‘reserves’, hubs of infrastructure, and natural laboratories.
Exceptional Times, Emergency Borders
Authors: Vaughan-Williams Nick 
Published: June 2021

Abstract
Chapter 2 examines the role of elite governmental actors in producing the narrative of the so-called 2015 ‘migration crisis’ and creating the conditions under which walling and deterrent border security policies flourished. The first part of the chapter draws on key press releases, speeches, and policy documents issued by the EU Commission and its agencies in order to map the emergence and trajectory of this elite ‘crisis’ narrative from the so-called ‘ghost ship’ arrivals to the height of ‘irregular’ arrivals that year. The second part shows how this ahistorical, Euro-centric, and (post)colonial governmental frame—with its reductionist depiction of mobile populations and sanitized one-sided view of border-related violence—has been problematized and disaggregated by research that documents the experiences of those seeking entry to the EU. The third part draws on theoretical literatures on the politics of crisis in order to argue that, irrespective of its empirical accuracy, the so-called ‘crisis’ narrative has enabled the intensification of deterrent border security measures on- and off-shore and the re-emergence of disciplinary walling techniques among EU Member States in ways that would be otherwise unpalatable in liberal democracies during ‘non-crisis’ times. But while extant work on crisis enables a critical analysis of the politics of ‘crisis bordering’ that is essential for any attempt to grapple with the book’s overarching puzzle, ultimately it falls short of explaining why populist calls to ‘take back control’ have been stoked rather than satiated by such bordering and therefore it is necessary to investigate those calls—and their reception—among diverse publics in closer detail.
Desecuritizing Strangeness
Authors: Vaughan-Williams Nick 
Published: June 2021

Abstract
Chapter 6 recovers vernacular counter-narratives of the border and alternative border imaginaries at work in citizens’ conversations. Beyond dominant narratives of crisis, securitization, abjection, and control, the analysis shows how some vernacular accounts mobilized border logics that questioned portrayals of obsessive walling practices as immutable and inevitable and thus disrupted elite scripts of the ‘crisis’. It is argued that another reason why populist calls to ‘take back control’ flourished despite augmented border security is that actually existing alternative imaginaries among citizens were subjugated in wider public discourse. The discussion begins by recalling the ‘affective atmospheres of welcoming’ that swept across the EU during the summer of 2015. While some vernacular narratives arguably perpetuated a problematic politics of pity akin to many elite governmental narratives of humanitarian crisis, others made arguments about EU citizens’ duties to new arrivals based on a politics of equality and/or of an awareness of the legacies of European colonialism. From here, the analysis considers a range of vernacular narratives that in various ways challenged the notion that there is ‘no alternative’ to tougher deterrent border security and walling. Finally, the chapter mines citizens’ vernacular narratives that do not start with abstract arguments about ‘borders’ at all. In such narratives we find glimpses of what Kristeva (1991) refers to as an ‘ethics of strangeness’: refusals of sovereign mastery of control, the fantasy of ontological security, and the desire to be ‘bordered’. This disrupts the grip of the dominant elite ‘crisis’ narrative and offers new grounds to engage the challenges wrought by increased arrivals and deaths at sea.
Violence, Sovereignty, and the Uganda Police Force
Authors: Tapscott Rebecca 
Published: June 2021

Abstract
How does the Ugandan state produce and sustain the perception among citizens that it commands overwhelming violence? Through a study of the Uganda Police Force, this chapter examines four elements that blur the distinction between lawful and exceptional violence: first, institutional fragmentation obscures the source of violence and undermines accountability; second, the militarization of state and society confuses who can legally purvey violence on behalf of the state; third, the regime engineers law to mask exceptional acts of state violence as lawful; and finally, spectacular and public acts of violence, such as elite assassinations, create widespread speculation about and fear of exceptional state violence. As a result, state violence is unpredictable both in its intensity and its accountability. The manipulation of the relationship between lawful and exceptional violence produces and sustains both fear and hope, making it difficult for ordinary citizens to manage or ignore the possibility of state intervention.
Whither the State?
Authors: Tapscott Rebecca 
Published: June 2021

Abstract
The chapter studies the complex relationship between state and society, drawing on scholars including Timothy Mitchell and Joel Migdal who see the distinction between state and society as produced through practice. It looks at how Uganda’s ruling regime manipulates the relationship between state presence and absence, such that citizens are sometimes categorized as outside the state, sometimes as agents of the state, and—most often—placed in a liminal space where their standing vis-à-vis the state is ambiguous. The chapter examines Uganda’s flagship community policing programme, Crime Preventers, described as a ‘floating population’ that works as the regime’s ‘eyes and ears’ across the country. By mobilizing crime preventers, the regime fostered the possibility of state presence while keeping crime preventers themselves in a liminal space from which they could make few claims on state authorities.
Arbitrary Governance in Africa and Beyond
Authors: Tapscott Rebecca 
Published: June 2021

Abstract
The book concludes with a discussion of the theoretical and empirical implications of arbitrary governance today. It highlights the implications of the findings for literature on authoritarian regimes and state formation, and looks at the additional cases of Ethiopia, Rwanda, and Zimbabwe to further probe the external validity of the theory. The analysis shows that aspects of arbitrary governance are common across cases, and that institutionalized arbitrariness can usefully be applied beyond Uganda. The chapter concludes by discussing avenues for future research, including how international aid and improvements in surveillance technologies shape arbitrary governance, and the resultant dynamics between state and society in this type of modern authoritarian regime.
The Advent of a New Banking System in the US
Authors: Cunha João Rafael 
Published: June 2021

Abstract
The 1980s was one of the most eventful and consequential decades in the development of the US financial system. During this decade, the regulatory framework established in response to the Great Depression started to be dismantled. These regulatory changes were a key driving force behind the transformation of the banking sector. Moreover, the end of the decade saw the most serious banking crisis since the Great Depression. This pattern of deregulation and crises, which started in the 1980s, has continued until the present. Thus, it is worth study this period in greater detail and the consequences it has had for the US banking and financial system. The chapter argues that the deregulatory process that started in the 1980s in the banking industry in the United States has changed the profile of this sector. Between the Great Depression and the 1980s, the banking sector in the United States was a stable, yet not competitive sector. The financial deregulation of the 1980s changed this sector to a competitive, yet unstable one. This deregulatory process occurred mostly as a response to the economic conditions of the 1970s.
Fifty Years of Financial Regulation in Germany
Authors: Kaserer Christoph 
Published: June 2021

Abstract
This chapter gives an overview on how financial market regulation evolved in Germany since the 1970s. The picture presented is somehow contradicting, as it seems that banking regulation and capital market regulation evolved in a quite different way. As far as banking regulation is concerned, it will be shown that starting with the Herstatt crisis in 1974 there was a clear trend towards tightening and increasing the regulatory perimeter. By analysing how the budget of the German banking supervision authority evolved since 1988, this claim will also be corroborated empirically. The picture with respect to capital market regulation is quite different, however. Here, the regulatory process started back in the year 1990 and, at least for the first decade, it was focused towards liberalizing and modernizing the German capital market. It will be argued that there is an underlying public choice mechanism able to explain this different development in two adjacent areas of financial market regulation.