A genuine continuum treatment of the massive 1ϩ1 4 theory in light-cone quantization is proposed. Fields are treated as operator-valued distributions, thereby leading to a mathematically well-defined handling of ultraviolet-and light-cone-induced infrared divergences and of their renormalization. Although nonperturbative, the continuum light-cone approach is no more complex than usual perturbation theory in lowest order. Relative to discretized light-cone quantization, the critical coupling increases by 30% to a value rϭ1.5. Conventional perturbation theory at the corresponding order yields r 1 ϭ1, whereas the RG-improved fourthorder result is r 4 ϭ1.8Ϯ0.05. ͓S0556-2821͑98͒00308-7͔

To treat the front-form Hamiltonian approach to quantum field theory, called light cone quantum field theory, in a mathematically rigorous way, the existence of a well-defined restriction of the corresponding free fields to the hypersurface ͕x 0 ϩx 3 ϭ0͖ in Minkowski space is of an essential necessity. However, even in the situation of a real scalar free field such a restriction does canonically not exist; this is called the restriction problem. Furthermore, since the beginning of light cone quantum field theory there is the problem of nonexistence of a well-defined Fock space expansion of a free quantum field in terms of light cone momenta which is called the zero-mode problem. In this paper we present solutions to these long outstanding problems where the study of the zero-mode problem ͑of the corresponding classical field͒ will lead us to a solution of the restriction problem. We introduce a new function space of ''squeezed'' smooth functions which can canonically be embedded into the Schwartz space S(R 3 ). The restriction of the free field to ͕x 0 ϩx 3 ϭ0͖ is canonically definable on this function space and we show that the covariant field is uniquely determined by this ''tame'' restriction.

This article analyses protesters’ reactions to police video surveillance of demonstrations in Germany. Theoretically, we draw on the concept of a “spiral of surveillance and counter-surveillance” to understand the interaction processes which—intentionally or not—contribute to the deepening of the “surveillant assemblage” in the field of protest policing. After introducing video surveillance and its importance for selective protest policing, we discuss concepts of counter-surveillance. Widening the individualist scope of former research on “neutralisation techniques,” collective and interactive dimensions are added to cover the full counter-surveillance repertoire. We identified six basic categories of counter-surveillance moves: consider cameras, disguise, attack, hide, sousveillance, and cooperation. They can be classified along the axes of (a) degree of cooperation with the police, and (b) directedness (inwards/outward). It becomes obvious that activists are not predominantly deterred by video surveillance but adapt to the situation. If and how certain counter-surveillance moves are applied depends on the degree of exposure, perceptions of conflict dynamics, political interpretations, and on how these factors are processed in the respective security cultures. Security cultures, which are grounded in the respective relations between protest groups and police, are collective sets of practices and interpretive patterns aimed at securing safety and/or anonymity of activists as well as making their claims visible. Thus, they are productive power effects, resulting from the very conditions under which protest takes place in contemporary surveillance societies. This article elaborates on these ambiguities and unintended effects with regard to sousveillance and disguise techniques, such as masking or uniform clothing. The analysis is based on qualitative data collected between 2011 and 2016 consisting of group discussions and interviews with activists from different political spectra, journalists, politicians, and police officers, as well as observations of demonstrations and document analyses of movement literature.

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