scholarly journals A conformally invariant sphere theorem in four dimensions

2003 ◽  
Vol 98 (1) ◽  
pp. 105-143 ◽  
Author(s):  
Sun-Yung A. Chang ◽  
Matthew J. Gursky ◽  
Paul C. Yang
Keyword(s):  
Sphere Theorem ◽  
Four Dimensions ◽  
Conformally Invariant ◽  
Invariant Sphere

TOWARDS A CONFORMAL QED4 WITH A NONVANISHING CURRENT 2-POINT FUNCTION

1988 ◽  
Vol 03 (04) ◽  
pp. 1023-1049 ◽  
Author(s):  
YASSEN S. STANEV ◽  
IVAN T. TODOROV
Keyword(s):  
Quantum Electrodynamics ◽  
Anomalous Dimension ◽  
Operator Product ◽  
Indefinite Metric ◽  
Conformal Invariant ◽  
Point Function ◽  
Four Dimensions ◽  
Conformally Invariant ◽  
Longitudinal Correlation ◽  
Electron Field

The possibility of constructing a conformally invariant model of spinor quantum electrodynamics (QED) in four dimensions involving an anomalous dimension of the electron field and a general indecomposable conformal law for the Maxwell field Fµν is studied within the local indefinite metric framework making systematic use of conformal operator product expansions (OPEs). It is demonstrated that the standard elementary conformal law for Fµν, which is known to yield a vanishing current-current 2-point function leads to a trivial theory. On the other hand, the conformal invariant 2-point function <Jμ(x1)Jν(x2)> (proportional to the second order perturbation theory expression in a massless QED) gives rise to a soluble conformal model involving [Formula: see text] and a vector field Vµ with longitudinal correlation function. The question whether the model can be extended to include Fµν (rather than its divergence) remains unresolved.

The effects of conformally invariant Maxwell source on the magnetic wormhole solutions in Gauss–Bonnet gravity

2011 ◽  
Vol 89 (3) ◽  
pp. 281-287 ◽  
Author(s):  
S. H. Hendi
Keyword(s):  
Electric Charge ◽  
Rotation Parameter ◽  
Energy Conditions ◽  
Conserved Quantities ◽  
Bonnet Gravity ◽  
Four Dimensions ◽  
Conformally Invariant ◽  
New Class ◽  
Traversable Wormholes ◽  
Higher Dimensional

In this paper we introduce a new class of nonsingular higher dimensional conformally invariant magnetic solutions that may be interpreted as traversable wormholes, which could be supported by matter not violating the weak energy conditions. The electromagnetic source is chosen in which the expression of the Maxwell field does not depend on the dimension and its value coincides with the Reissner–Nordström solution in four dimensions. We generalize this class of solutions to the case of rotating solutions and show that the rotating wormhole solutions have a net electric charge that is proportional to the magnitude of the rotation parameter, while the static wormhole has no net electric charge. Finally, we use the counterterm method and compute the conserved quantities of these spacetimes.

scholarly journals The averaged null energy conditions in even dimensional curved spacetimes from AdS/CFT duality

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Norihiro Iizuka ◽  
Akihiro Ishibashi ◽  
Kengo Maeda
Keyword(s):  
Weight Function ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Two Dimensions ◽  
Energy Conditions ◽  
Quantum Field Theories ◽  
Strongly Coupled ◽  
Four Dimensions ◽  
Conformally Invariant ◽  
Curved Spacetimes

Abstract We consider averaged null energy conditions (ANEC) for strongly coupled quantum field theories in even (two and four) dimensional curved spacetimes by applying the no-bulk-shortcut principle in the context of the AdS/CFT duality. In the same context but in odd-dimensions, the present authors previously derived a conformally invariant averaged null energy condition (CANEC), which is a version of the ANEC with a certain weight function for conformal invariance. In even-dimensions, however, one has to deal with gravitational conformal anomalies, which make relevant formulas much more complicated than the odd-dimensional case. In two-dimensions, we derive the ANEC by applying the no-bulk-shortcut principle. In four-dimensions, we derive an inequality which essentially provides the lower-bound for the ANEC with a weight function. For this purpose, and also to get some geometric insights into gravitational conformal anomalies, we express the stress-energy formulas in terms of geometric quantities such as the expansions of boundary null geodesics and a quasi-local mass of the boundary geometry. We argue when the lowest bound is achieved and also discuss when the averaged value of the null energy can be negative, considering a simple example of a spatially compact universe with wormhole throat.

scholarly journals Four–dimensional metrics conformal to Kähler

2010 ◽  
Vol 148 (3) ◽  
pp. 485-503 ◽  
Author(s):  
MACIEJ DUNAJSKI ◽  
PAUL TOD
Keyword(s):  
Conformal Structure ◽  
Projective Structure ◽  
Conformal Class ◽  
Projective Structures ◽  
Weyl Spinor ◽  
Kähler Metric ◽  
Four Dimensions ◽  
Conformal Curvature ◽  
Conformally Invariant ◽  
Kahler Metric

AbstractWe derive some necessary conditions on a Riemannian metric (M, g) in four dimensions for it to be locally conformal to Kähler. If the conformal curvature is non anti–self–dual, the self–dual Weyl spinor must be of algebraic type D and satisfy a simple first order conformally invariant condition which is necessary and sufficient for the existence of a Kähler metric in the conformal class. In the anti–self–dual case we establish a one to one correspondence between Kähler metrics in the conformal class and non–zero parallel sections of a certain connection on a natural rank ten vector bundle over M. We use this characterisation to provide examples of ASD metrics which are not conformal to Kähler.We establish a link between the ‘conformal to Kähler condition’ in dimension four and the metrisability of projective structures in dimension two. A projective structure on a surface U is metrisable if and only if the induced (2, 2) conformal structure on M = TU admits a Kähler metric or a para–Kähler metric.

FACT-2 – The Frankfurt Adaptive Concentration Test

2009 ◽  
Vol 25 (2) ◽  
pp. 73-82 ◽  
Author(s):  
Frank Goldhammer ◽  
Helfried Moosbrugger ◽  
Sabine A. Krawietz
Keyword(s):  
Convergent Validity ◽  
Four Dimensions ◽  
Measurement Models ◽  
Cognitive Failures ◽  
Concentration Test ◽  
Cognitive Failures Questionnaire

The Frankfurt Adaptive Concentration Test (FACT-2) requires discrimination between geometric target and nontarget items as quickly and accurately as possible. Three forms of the FACT-2 were constructed, namely FACT-I, FACT-S, and FACT-SR. The aim of the present study was to investigate the convergent validity of the FACT-SR with self-reported cognitive failures. The FACT-SR and the Cognitive Failures Questionnaire (CFQ) were completed by 191 participants. The measurement models confirmed the concentration performance, concentration accuracy, and concentration homogeneity dimensions of FACT-SR. The four dimensions of the CFQ (i.e., memory, distractibility, blunders, and names) were not confirmed. The results showed moderate convergent validity of concentration performance, concentration accuracy, and concentration homogeneity with two CFQ dimensions, namely memory and distractibility/blunders.

The Four Dimensions Of The Catalan Model

2000 ◽  
Vol 33 (First Serie (1) ◽  
pp. 100-111
Author(s):  
Pau Piuig i Scotoni
Keyword(s):  
Four Dimensions

A JOURNEY TO MEASURE STUDENT COMMUNITY ENGAGEMENT BENEFITS: EVIDENCE FROM AUSTRALIA

2019 ◽  
Vol 1 (1) ◽  
pp. 16
Author(s):  
Ellen Chung ◽  
Hamish B Coates
Keyword(s):  
Community Engagement ◽  
Undergraduate Students ◽  
Factor Loading ◽  
Higher Learning ◽  
Four Dimensions ◽  
Student Community ◽  
Institutions Of Higher Learning ◽  
Final Questionnaire ◽  
Civic Skills ◽  
Career Skills

Community engagement is a phenomenon that has received increasing attention among institutions of higher learning in recent years, and students engaging with communities are generally seen as beneficial. Given this, surprisingly little is known about this form of engagement in Australian higher education, let alone methods to measure its benefits on students. This study discussed the development of the Student Community Engagement Benefits Questionnaire (SCEBS), a questionnaire that measures the perceptions of community engagement benefits among undergraduate students in Australia. The final questionnaire has 32 items allocated to four benefit scales: (1) Career skills, (2) Diversity skills, (3) Interpersonal skills, (4) Civic skills. Most benefit items had a factor loading of atleast 0.40 with its own scale. The results of the factor analysis revealed that the four scales accounted for 53% of the total variance. The alpha reliability coefficient for the four scales ranged from 0.79 to 0.91. Based on these findings, the Student Community Engagement Benefits Scale (SCEBS) is a valid and reliable instrument that can be used in the field of education. Undergraduate students also reported statistically significant changes in the four dimensions after participating in community engagement activities.

Gender and belief factors on attitude towards Social and Environmental Accounting (SEA)

2009 ◽  
Vol 6 (2) ◽  
pp. 51
Author(s):  
Salina Abdullah ◽  
Ern Chen Loo
Keyword(s):  
Natural Resources ◽  
Undergraduate Students ◽  
Environmental Issues ◽  
Environmental Accounting ◽  
Future Generations ◽  
Business And Society ◽  
Four Dimensions ◽  
Sustain Ability ◽  
The Relationship

Research on social and environmental accounting (SEA) has mainly concentrated on disclosure of SEA by corporate bodies, where investigations on ones attitude towards SEA are rarely discussed. SEA is a medium that develops relationships between business and society, community and nature. In addition, SEA involves a concept of sustain ability; where natural resources need to be sustained for the needs of future generations (Alhabshi et al., 2003). SEA also tries to recognise the role of accounting in sustainable development and the use of environmental resources. There are arguments that the young generations today are not fully aware of preserving these natural resources as well as handling social and environmental issues wisely. This perhaps link closely to their belief and cultural background. Hence, this paper examines the influence of gender and belief factors on the undergraduate students’ attitude towards SEA. Four dimensions of belief (fixed ability, quick learning, simple knowledge and certain knowledge) proposed by Schommer (2005) were adapted to analyse how belief factors have influence on their attitude towards SEA. An independent sample t-test was used to examine the relationship between gender and students’ attitude towards SEA. Spearmen’s correlation was employed to show the relationship between belief and attitude towards SEA. The results revealed that gender differences did not show influences on their attitude towards SEA. It was found that there is a significant relationship between belief and students’ attitude towards SEA. Students who believe on the importance of SEA tend to report positive attitude towards SEA. Perhaps findings of this study may provide some information on the SEA education and further be incorporated in the syllabus.

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