Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2020 ( 2 )

2019 ( 191 )

2018 ( 247 )

2017 ( 249 )

Custom range...

Search Results: 1 - 10 of 192476 matches for " D. Dietrich "
All listed articles are free for downloading (OA Articles)
Page 1 /192476
Display every page Item
The surprising photochemistry of sultams related to saccharin
Dietrich D pp
International Journal of Photoenergy , 2001, DOI: 10.1155/s1110662x01000058
Abstract: The known light induced reactions of sulfonamides and sultams are in most (but not all) cases initiated by S–N homolysis. Sulfur dioxide release may be a consequence of this primary process. In the author's laboratory three hitherto unexplored photoreactions of saccharin-derived sultams have been investigated: (i) a novel formal oxygen shift from sulfur to nitrogen generating upto now unknown cyclic N-hydroxysulfinamides; (ii) a condensative dimerization of 2,3-dihydro-1,2- benzoisothiazole 1,1-dioxide generating a new cleft molecule, and (iii) a facile allylic skeletal rearrangement of a pyrrolo-anellated dihydro- 1,2-benzoisothiazole. At least in the latter two cases an initial S–N-homolysis seems to be vital for the processes observed, whereas in the first case some ambiguity remains with respect to the first step. Scope and limitations are discussed and rationales for the conversions observed are presented, with special emphasis on structure proof by X-ray crystal structure determinations. All reactions discussed have to be treated within the wider context of current sulfonamide and sultam photochemistry.
A mass-dependent beta-function
Dennis D. Dietrich
Physics , 2009, DOI: 10.1103/PhysRevD.80.065032
Abstract: Threshold effects related to fermion masses are considered for an all-order beta-function based on a background field momentum subtraction scheme. Far away from all thresholds, the suggested beta-function reduces to the conjectured all-order form inspired by the Novikov-Shifman-Vainshtein-Zakharov beta-function of N=1 supersymmetric gauge theories with a fixed integer number of fermion flavours. At (formally) infinite masses the corresponding pure Yang--Mills beta-function is recovered. We discuss applications to the phase diagram of non-Abelian field theories.
Concerning gauge field fluctuations around classical configurations
Dennis D. Dietrich
Physics , 2009, DOI: 10.1103/PhysRevD.79.107703
Abstract: We treat the fluctuations of non-Abelian gauge fields around a classical configuration by means of a transformation from the Yang--Mills gauge field to a homogeneously transforming field variable. We use the formalism to compute the effective action induced by these fluctuations in a static background without Wu--Yang ambiguity.
Quasiconformality and mass
Dennis D. Dietrich
Physics , 2010, DOI: 10.1103/PhysRevD.82.065007
Abstract: We identify universal quasiconformal (walking) behaviour in non-Abelian gauge field theories based on the mass-dependent all-order beta-function introduced in arXiv:0908.1364. We find different types of walking behaviour in the presence of (partially) massive species. We employ our findings to the construction of candidate theories for dynamical electroweak symmetry breaking by walking technicolour.
Fermion production in time-dependent fields
Dennis D. Dietrich
Physics , 2003, DOI: 10.1103/PhysRevD.68.105005
Abstract: The exact fermion propagator in a classical time-dependent gauge field is derived by solving the equation of motion for the Dirac Green's functions. From the retarded propagator obtained in this way the momentum spectrum for the produced fermion pairs is calculated. Different approximations and the exact solution for the propagator and the momentum spectrum are presented.
Quark-antiquark pair production in space-time dependent fields
Dennis. D. Dietrich
Physics , 2004, DOI: 10.1103/PhysRevD.70.105009
Abstract: Fermion-antifermion pair-production in the presence of classical fields is described based on the retarded and advanced fermion propagators. They are obtained by solving the equation of motion for the Dirac Green's functions with the respective boundary conditions to all orders in the field. Subsequently, various approximation schemes fit for different field configurations are explained. This includes longitudinally boost-invariant forms. Those occur frequently in the description of ultrarelativistic heavy-ion collisions in the semiclassical limit. As a next step, the gauge invariance of the expression for the expectation value of the number of produced fermion-antifermion pairs as a functional of said propagators is investigated in detail. Finally, the calculations are carried out for a longitudinally boost-invariant model-field, taking care of the last issue, especially.
Worldline holographic Schwinger effect
Dennis D. Dietrich
Physics , 2014, DOI: 10.1103/PhysRevD.90.045024
Abstract: The decay of the vacuum due to the presence of an electric field is expected to be delayed by a confining force. We demonstrate that this feature is captured by our model [arXiv:1404.0011 [hep-ph],arXiv:1312.5718 [hep-ph]] for hadrons based on the worldline formalism. Our model, while based entirely in four-dimensional quantum field theory, shares many features with holographic approaches: it appears intrinsically quantum mechanical; as an auxiliary fifth dimension Schwinger's proper time combines with the physical four spacetime dimensions into an AdS$_5$ geometry; conformal-symmetry breaking contributions lead to warping; hidden local symmetry emerges; four-dimensional sources are extended to five-dimensional fields by a Wilson flow (gradient flow); and a variational principle for this flow reproduces the corresponding holographic calculation. The approach also yields the higher-dimensional description in the non-relativistic case.
On invariants for particle propagation in non-Abelian fields
Dennis D. Dietrich
Physics , 2009, DOI: 10.1103/PhysRevD.80.067701
Abstract: Characterising the propagation of particles in an external non-Abelian field only in terms of invariants constructed from its field tensor is not always sufficient, especially, in many analytically tractable and phenomenologically interesting cases.
Hadrons on the worldline, holography, and Wilson flow
Dennis D. Dietrich
Physics , 2013, DOI: 10.1103/PhysRevD.89.086005
Abstract: Holographic principles have impacted the way we look at strong coupling phenomena in quantum chromodynamics, strongly interacting extensions of the standard model, and {condensed-matter} physics. In real world settings, however, we still lack understanding of why and when such an approach is justified. Therefore, here, without invoking any such principle a priori, we demonstrate how such a picture arises in the worldline formulation of quantum field theory. Among other connections to holographic models, a warped AdS5 geometry, a quantum mechanical picture, and hidden local symmetry emerge, as well as a Wilson flow (gradient flow), which extends the four-dimensional sources to five-dimensional fields and a link to the Gutzwiller trace formula. The worldline formulation also reproduces the non-relativistic case, which is important for condensed-matter physics.
The fifth dimension in the worldline formalism, holography, and the Wilson flow
Dennis D. Dietrich
Physics , 2014, DOI: 10.1103/PhysRevD.89.106009
Abstract: We develop a model for hadrons in the framework of the worldline formalism. While being based wholly in four-dimensional quantum field theory, it shares many features with holographic approaches: Already by the use of the worldline formalism the approach appears intrinsically quantum mechanical. As auxiliary fifth dimension Schwinger's proper time is grouped with the physical four spacetime dimensions into an AdS5 geometry, which is warped due to conformal-symmetry breaking effects. Hidden local symmetry is emergent. The four-dimensional sources are extended to five-dimensional fields by a Wilson flow (gradient flow). A variational principle for the flow reproduces exactly the corresponding holographic computation. The worldline approach also yields the higher-dimensional description in the non-relativistic case.
Page 1 /192476
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.