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Hartmann Roemer

Publications and source records attributed to Hartmann Roemer.

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Order Effects in Sequential Measurements of Non-Commuting Psychological Observables

Sequential measurements of non-commuting observables produce order effects that are well-known in quantum physics. But their conceptual basis, a significant measurement interaction, is relevant for far more general situations. We argue that non-commutativity is ubiquitous in psychology where almost every interaction with a mental system changes that system in an uncontrollable fashion. Psychological order effects for sequential measurements are therefore to be expected as a rule. In this paper we focus on the theoretical basis of such effects. We classify several families of order effects theoretically, relate them to psychological observations, and predict effects yet to be discovered empirically. We assess the complexity, related to the predictive power, of particular (Hilbert space) models of order effects and discuss possible limitations of such models.

physics.data-an

Complementarity of Process and Substance

Process Philosophy endeavours to replace the classical ontology of substances by a process ontology centered on notions of changes and transitions. We argue, that the substantial and processual approach are mutually complementary. Here, complementarity is to be understood in the sense of a "Generalized Quantum Theory", which is not restricted to physical phenomena. From this point of view, restricting oneself to either substance or process ontology would be as ill-advised as exclusively relying on position or momentum observables in physics. A new view on Zeno's paradox lends itself. The meaning of an "internal energy observable", complementary to inner time, and its relationship to "akategorial states" of the human mind will also be discussed.

quant-ph

Convergence of the Wick Star Product

We construct a Frechet space as a subspace of C^ω(C^n) where the Wick star product converges and is continuous. The resulting Frechet algebra A_h is studied in detail including a *-representation of A_h in the Bargmann-Fock space and a discussion of star exponentials and coherent states.

math.QA

The Poisson Bracket for Poisson Forms in Multisymplectic Field Theory

We present a general definition of the Poisson bracket between differential forms on the extended multiphase space appearing in the geometric formulation of first order classical field theories and, more generally, on exact multisymplectic manifolds. It is well defined for a certain class of differential forms that we propose to call Poisson forms and turns the space of Poisson forms into a Lie superalgebra.

math-ph

Dynamics of the Born-Infeld dyons

The approach to the dynamics of a charged particle in the Born-Infeld nonlinear electrodynamics developed in [Phys. Lett. A 240 (1998) 8] is generalized to include a Born-Infeld dyon. Both Hamiltonian and Lagrangian structures of many dyons interacting with nonlinear electromagnetism are constructed. All results are manifestly duality invariant.

hep-th

A Remark on Formal KMS States in Deformation Quantization

In the framework of deformation quantization we define formal KMS states on the deformed algebra of power series of functions with compact support in phase space as C[[λ]]-linear functionals obeying a formal variant of the usual KMS condition known in the theory of C^*-algebras. We show that for each temperature KMS states always exist and are up to a normalization equal to the trace of the argument multiplied by a formal analogue of the usual Boltzmann factor, a certain formal star exponential.

math.QA