135,143 research outputs found
Covariant actions for the bosonic sector of D = 10 IIB supergravity
No full textCovariant actions for the bosonic fields of D = 10 IIB supergravity are constructed with the help of a single auxiliary scalar field in a formulation with an infinite series of auxiliary (anti-)self-dual 5-form fields
String κ-anomalies and D = 10 supergravity constraints: the solution of a puzzle
No full textThe κ-anomaly cancellation mechanism in the heterotic superstring determines the superspace constraints for N = 1, D = 10 Supergravity-Super-Yang-Mills theory. We point out that the constraints found recently in this way appear to disagree with superspace solutions found in the past. We solve this puzzle establishing perfect agreement between the two methods. © 1995
Intersecting D-branes, Chern-kernels and the inflow mechanism
No full textWe analyse a system of arbitrarily intersecting D–branes in ten–
dimensional supergravity. Chiral anomalies are supported on the intersection branes,
called I–branes. For non–transversal intersections anomaly cancellation has been
realized until now only cohomologically but not locally, due to short–distance singularities.
In this paper we present a consistent local cancellation mechanism, writing
the –like brane currents as differentials of the recently introduced Chern–kernels,
J = dK. In particular, for the first time we achieve anomaly cancellation for dual
pairs of D–branes. The Chern–kernel approach allows to construct an effective action
for the RR–fields which is free from singularities and cancels the quantum anomalies
on all D–branes and I–branes
Modular Nuclearity and Localization
No full textWithin the algebraic setting of quantum field theory, a condition is given which implies that the intersection of algebras generated by field operators localized in wedge-shaped regions of the two-dimensional Minkowski space is non-trivial; in particular, there exist compactly localized operators in such theories which can be interpreted as local observables. The condition is based on spectral (nuclearity) properties of the modular operators affiliated with wedge algebras and the vacuum state and is of interest in the algebraic approach to the formfactor program, initiated by Schroer. It is illustrated here in a simple class of examples
Konsertot, oboe, jousiork., BWV1059R, d-molli
No full textSoitinnus: cembalo, oboe, jousiorkesteri.Äänitetty radiosta.Esittäjätiedot radiokuulutuksesta.Deutsche Bachsolisten -yhtyeen konsertti Turun musiikkijuhlilla.Irmgard Lechner (cembalo), Helmut Winschermann (oboe), Deutsche Bachsolisten.Äänitetty: [13.6.1962, Turku (konserttitaltiointi)].Digitoitu 22. 2. 201
On p-form gauge theories and their conformal limits
No full textRelations between the various formulations of nonlinear p-form electrodynamics with conformal-invariant weak-field and strong-field limits are clarified, with a focus on duality invariant (2n − 1)-form electrodynamics and chiral 2n-form electrodynamics in Minkowski spacetime of dimension D = 4n and D = 4n + 2, respectively. We exhibit a new family of chiral 2-form electrodynamics in D = 6 for which these limits exhaust the possibilities for conformal invariance; the weak-field limit is related by dimensional reduction to the recently discovered ModMax generalisation of Maxwell’s equations. For n > 1 we show that the chiral ‘strong-field’ 2n-form electrodynamics is related by dimensional reduction to a new Sl(2; R)-duality invariant theory of (2n − 1)-form electrodynamics
Networks and the Decision to Persist with Underperforming R&D Projects
No full textDrawing on aspiration level theory and the networks literature, this paper develops a model toward decision makers' persistence with underperforming R&D projects based on the perceived properties of their personal network. The assumption is that positive feedback from network partners motivates persistence, and that this effect is multiplied when the decision makers' network is larger and denser, when network ties are predominantly strong, and when communication frequency within the network is high. The model is tested by a field experiment and conjoint methodology. Analysis of 1632 persistence decisions nested within 51 scientists responsible for R&D projects reveals that more positive feedback enhances persistence of underperforming R&D projects, and that this effect becomes stronger with increasing network size, network density, and communication frequency. These findings extend the project management literature by focusing on the social environment of the decision maker as one so far neglected factor in empirical studies on persistence decisions. Moreover, this study is among the first to investigate contingency relationships between feedback received from network partners and network structure. Finally, while most studies have emphasized that individuals and organizations can profit from their engagements in social networks, this paper suggests a potential dark side of networks by showing that networks can encourage decision makers to persist with their investment in an underperforming-and potentially failing-project. These results can help project managers involved in networking activities to better understand the effects of these activities on their decision policies, and thus draw better and more accurate decisions. Second, this study provides insights into how organizational strategy with respect to dissemination of R&D results and involvement of the organization's R&D managers in the scientific community influences the persistence of underperforming R&D projects, and thereby the organization's R&D expenditures. This can assist top managers to design financial controls and allocate financial resources to managers of underperforming R&D projects in line with the organization's networking strategy
Nonlinear duality-invariant conformal extension of Maxwell's equations
No full textAll nonlinear extensions of the source-free Maxwell equations preserving both SO(2) electromagnetic duality invariance and conformal invariance are found, and shown to be limits of a one-parameter generalization of Born-Infeld electrodynamics. The strong-field limit is the same as that found by Bialynicki-Birula from Born-Infeld theory but the weak-field limit is a new one-parameter extension of Maxwell electrodynamics, which is interacting but admits exact light-velocity plane-wave solutions of arbitrary polarization. Small-amplitude waves on a constant uniform electromagnetic background exhibit birefringence, but one polarization mode remains lightlike
4-GRAVITON SCATTERING IN D = 4 SUPERSTRINGS WITH BROKEN SPACE-TIME SUPERSYMMETRY
No full textWe construct the one-loop four-graviton amplitude in a four-dimensional type II superstring model with broken (N = 4) space-time SUSY. The amplitude is seen to be a sum of the amplitude with unbroken highest N = 8 SUSY, A8, plus a term A4 which breaks SUSY down to N = 4. The new term A4 is seen to contain rescattering diagrams, which are also present in A8, and to open one-particle-reducible channels containing gravitons, due to the absence of non-renormalization theorems for it. The evaluation of the contributions to the amplitude of these channels in the limit of large external energies and of small momentum transfer confirms that the effective metric due to a graviton source is not of the classical Schwarzschild-type, not even at broken SUSY. Moreover, we check that, in spite of the absence of non-renormalization theorems, the graviton mass and wave function are not renormalized. We find infrared singularities in A4, which are not present in A8, individuate their nature and guess a ..
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