4,224 research outputs found
Translocality and a Duality Principle in Generally Covariant Quantum Field Theory
It is argued that the formal rules of correspondence between local
observation procedures and observables do not exhaust the entire physical
content of generally covariant quantum field theory. This result is obtained by
expressing the distinguishing features of the local kinematical structure of
quantum field theory in the generally covariant context in terms of a
translocal structure which carries the totality of the nonlocal kinematical
informations in a local region. This gives rise to a duality principle at the
dynamical level which emphasizes the significance of the underlying translocal
structure for modelling a minimal algebra around a given point. We discuss the
emergence of classical properties from this point of view.Comment: 12 pages. To appear in Classical Quantum Gravit
Exploring the critical success factors of virtual-agile IT projects: a grounded theory study
Business dynamics and competition have necessitated IT organizations to use virtual style of working depending on the principles of agile methods. Virtual-agile IT projects are most relevant in the context of software and web development, new product development and information system projects. Organizations where fulfilling the demands of clients, face several complexities during projects; mainly obstructed by differences in location, time, culture and working dynamics etc. This paper aims to explore some useful practices undertaken in IT industry to deal with such criticalities. The research uses qualitative methods and grounded theory methodology to generate emerging themes recognized as codes or concepts; which were further transformed into categories based on their properties and dimensions. Categories or sub-categories identified were arranged using coding paradigm which helped to identify a core-category. Consequently, the relationships were refined, arranged in a unique way in selective coding phase and a storyline was generated elaborating the relationships between various categories, sub-categories and concepts. Finally, a conclusion is made and recommendations are proposed for future research
Infrared cutoffs and the adiabatic limit in noncommutative spacetime
We discuss appropriate infrared cutoffs and their adiabatic limit for field
theories on the noncommutative Minkowski space in the Yang-Feldman formalism.
In order to do this, we consider a mass term as interaction term. We show that
an infrared cutoff can be defined quite analogously to the commutative case and
that the adiabatic limit of the two-point function exists and coincides with
the expectation, to all orders.Comment: 19 page
Comment on: Modular Theory and Geometry
In this note we comment on part of a recent article by B. Schroer and H.-W.
Wiesbrock. Therein they calculate some new modular structure for the
U(1)-current-algebra (Weyl-algebra). We point out that their findings are true
in a more general setting. The split-property allows an extension to
doubly-localized algebras.Comment: 13 pages, corrected versio
There are No Causality Problems for Fermi's Two Atom System
A repeatedly discussed gedanken experiment, proposed by Fermi to check
Einstein causality, is reconsidered. It is shown that, contrary to a recent
statement made by Hegerfeldt, there appears no causality paradoxon in a proper
theoretical description of the experiment.Comment: 6 pages, latex, DESY 94-02
The Quest for Understanding in Relativistic Quantum Physics
We discuss the status and some perspectives of relativistic quantum physics.Comment: Invited contribution to the Special Issue 2000 of the Journal of
Mathematical Physics, 38 pages, typos corrected and references added, as to
appear in JM
Dynamical mapping method in nonrelativistic models of quantum field theory
The solutions of Heisenberg equations and two-particles eigenvalue problems
for nonrelativistic models of current-current fermion interaction and model are obtained in the frameworks of dynamical mapping method. The
equivalence of different types of dynamical mapping is shown. The connection
between renormalization procedure and theory of selfadjoint extensions is
elucidated.Comment: 14 page
A sharpened nuclearity condition for massless fields
A recently proposed phase space condition which comprises information about
the vacuum structure and timelike asymptotic behavior of physical states is
verified in massless free field theory. There follow interesting conclusions
about the momentum transfer of local operators in this model.Comment: 13 pages, LaTeX. As appeared in Letters in Mathematical Physic
Vacuum Structures in Hamiltonian Light-Front Dynamics
Hamiltonian light-front dynamics of quantum fields may provide a useful
approach to systematic non-perturbative approximations to quantum field
theories. We investigate inequivalent Hilbert-space representations of the
light-front field algebra in which the stability group of the light-front is
implemented by unitary transformations. The Hilbert space representation of
states is generated by the operator algebra from the vacuum state. There is a
large class of vacuum states besides the Fock vacuum which meet all the
invariance requirements. The light-front Hamiltonian must annihilate the vacuum
and have a positive spectrum. We exhibit relations of the Hamiltonian to the
nontrivial vacuum structure.Comment: 16 pages, report \# ANL-PHY-7524-TH-93, (Latex
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