scholarly journals The scalar-photon 3-point vertex in massless quenched scalar QED

2016 ◽  
Vol 761 ◽  
pp. 012063
Author(s):  
Y Concha-Sánchez ◽  
L X Gutiérrez-Guerrero ◽  
L A Fernández-Rangel
Keyword(s):  
Point Vertex

Abstract T P75: Vertex Analysis Demonstrates Significant Changes in Contralesional Thalamus 3 Months After Ischemic Stroke

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Nawaf Yassi ◽  
Bruce C Campbell ◽  
Andrew Bivard ◽  
Charles Malpas ◽  
Mark W Parsons ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Brain Structures ◽  
Recovery Phase ◽  
Subcortical Structures ◽  
Inferior Surface ◽  
Clinical Endpoints ◽  
Point Vertex ◽  
Number Of Patients ◽  
Surface Changes

Objective: Changes in remote brain structures after stroke may correlate with functional outcomes. We sought to investigate contralesional subcortical structural change after stroke. Methods: 15 patients with carotid territory ischemic stroke underwent 3T MRI within 7 days of onset and at 3 months. Imaging involved a 1mm T1 axial MPRAGE. In 6 patients with left hemispheric stroke, scans were inverted across the midline to allow group comparison. FIRST (Part of FSL) was used to segment subcortical structures including thalamus, pallidum, caudate, putamen, hippocampus, accumbens and brainstem. Analysis was restricted to the non-stroke hemisphere due to the confounding effect of stroke lesions and edema in the lesional hemisphere. Change in volume was assessed as percentage change between the time points. A vertex analysis was performed in order to also identify areas of significant surface atrophy. Briefly, a surface mesh is created for each structure at each time point. Vertex wise statistical analysis then allows for the identifications of areas of significant surface atrophy between baseline and follow-up within the group. Results: Mean age was 71y. Median baseline NIHSS was 9. Vertex analysis demonstrated atrophy over the superior and inferior surface of the contralesional thalamus between baseline and 3 months (figure, p<0.05 multiple comparisons corrected). The median overall change in contralesional thalamic volume was -0.96% (IQR -0.11 - -1.98%), but this difference was not statistically significant (p=0.1). No statistically significant changes in other subcortical structures were found. Contralesional thalamus (blue) superior (A) and inferior (B) views with areas of significant atrophy (red) Conclusions: We have described post stroke surface changes in the contralesional thalamus. This may be a result of deafferentation occurring during the recovery phase. An analysis in a larger number of patients may allow correlation with clinical endpoints.

scholarly journals CHORD DIAGRAMS AND BPHZ SUBTRACTIONS

1996 ◽  
Vol 11 (13) ◽  
pp. 1095-1105 ◽  
Author(s):  
IOANNIS TSOHANTJIS ◽  
ALEX C. KALLONIATIS ◽  
PETER D. JARVIS ◽  
GEORGE THOMPSON
Keyword(s):  
Field Theory ◽  
Knot Theory ◽  
Equivalence Relations ◽  
Quantum Field ◽  
Subtraction Scheme ◽  
Chord Diagrams ◽  
Point Vertex ◽  
Fundamental Relationship ◽  
Perturbative Quantum ◽  
Ladder Graphs

The combinatorics of the BPHZ subtraction scheme for a class of ladder graphs for the three-point vertex in ɸ3 theory is transcribed into certain connectivity relations for marked chord diagrams (knots with transversal intersections). The resolution of the singular crossings using the equivalence relations in these examples provides confirmation of a proposed fundamental relationship between knot theory and renormalization in perturbative quantum field theory.

Correspondence between the one-loop three-point vertex and the Y and Δ electric resistor networks

2014 ◽  
Vol 92 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Alfredo Takashi Suzuki
Keyword(s):  
Feynman Diagram ◽  
Hypergeometric Functions ◽  
Analytic Solution ◽  
Minimum Energy ◽  
Electric Circuit ◽  
Mathematical Methods ◽  
Resistor Networks ◽  
Point Vertex ◽  
The One ◽  
Circuit Networks

Different mathematical methods have been applied to obtain the analytic result for the massless triangle Feynman diagram yielding a sum of four linearly independent (LI) hypergeometric functions of two variables F4. This result is not physically acceptable when it is embedded in higher loops, because all four hypergeometric functions in the triangle result have the same region of convergence and further integration means going outside those regions of convergence. We could go outside those regions by using the well-known analytic continuation formulas obeyed by the F4, but there are at least two ways we can do this. Which is the correct one? Whichever continuation one uses, it reduces a number of F4 from four to three. This reduction in the number of hypergeometric functions can be understood by taking into account the fundamental physical constraint imposed by the conservation of momenta flowing along the three legs of the diagram. With this, the number of overall LI functions that enter the most general solution must reduce accordingly. It remains to determine which set of three LI solutions needs to be taken. To determine the exact structure and content of the analytic solution for the three-point function that can be embedded in higher loops, we use the analogy that exists between Feynman diagrams and electric circuit networks, in which the electric current flowing in the network plays the role of the momentum flowing in the lines of a Feynman diagram. This analogy is employed to define exactly which three out of the four hypergeometric functions are relevant to the analytic solution for the Feynman diagram. The analogy is built based on the equivalence between electric resistance circuit networks of types Y and Δ in which flows a conserved current. The equivalence is established via the theorem of minimum energy dissipation within circuits having these structures.

Weakly coupled gravity beyond general relativity

2015 ◽  
Vol 24 (12) ◽  
pp. 1544031 ◽  
Author(s):  
Xián O. Camanho ◽  
José D. Edelstein ◽  
Alexander Zhiboedov
Keyword(s):  
General Relativity ◽  
Time Delay ◽  
Wave Spectrum ◽  
Riemann Tensor ◽  
Spin States ◽  
Causality Violation ◽  
Novel Structure ◽  
Weakly Coupled ◽  
Point Vertex ◽  
Higher Spin

We explore four-dimensional (4D) weakly coupled gravity beyond general relativity in an on-shell language, focusing on the graviton three-point vertex. This admits a novel structure which can be attributed to a term cubic in the Riemann tensor. We consider a generalization of the Shapiro time delay experiment that involves polarized gravitons and show that the new vertex leads to causality violation. Fixing the problem demands the inclusion of an infinite tower of massive higher spin states. Perturbative string theory provides an example of this phenomenon, the only known so far. Interestingly enough, the same argument being applied to inflation suggests that stringy signatures may be hidden in the non-Gaussianities of the primordial gravity wave spectrum.

scholarly journals PELABELAN GRACEFUL GANJIL PADA GRAF DUPLIKASI DAN SPLIT BINTANG

2018 ◽  
Vol 15 (1) ◽  
pp. 28-35
Author(s):  
J A Bantara ◽  
I W Sudarsana ◽  
S Musdalifah
Keyword(s):  
Star Graph ◽  
Graceful Labeling ◽  
Set Point ◽  
Side Edge ◽  
Point Vertex

Graph  is not an empty a finite of the objects that called point (vertex) with the couple was not that is the side (edge). The set point  denoted by , while the set edge denoted by . Odd graceful labeling on graph  with  side is a function injective from so that induced function  such that  in label with  so label sides would be different. A graph  that have an odd graceful labeling is called odd graceful graph. The result showed that duplicate star graph  for and split star graph  for , for  even satisfie odd graceful labeling.

scholarly journals Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge

2017 ◽  
Vol 137 ◽  
pp. 03001 ◽  
Author(s):  
Adrian L. Blum ◽  
Reinhard Alkofer ◽  
Markus Q. Huber ◽  
Andreas Windisch
Keyword(s):  
Landau Gauge ◽  
Yang Mills ◽  
Point Vertex

scholarly journals Nonperturbative three-point vertex in massless quenched QED and perturbation theory constraints

1998 ◽  
Vol 57 (2) ◽  
pp. 1242-1249 ◽  
Author(s):  
A. Bashir ◽  
A. Kizilersü ◽  
M. R. Pennington
Keyword(s):  
Perturbation Theory ◽  
Point Vertex

Zero-Point Problem in Fixed-Point Gauge of Nonperturbative QCD

1997 ◽  
Vol 12 (27) ◽  
pp. 1983-1989 ◽  
Author(s):  
Jian-Jun Yang ◽  
Hong-Qing Shen ◽  
Guang-Lie Li
Keyword(s):  
Fixed Point ◽  
Zero Point ◽  
Point Problem ◽  
Gluon Condensates ◽  
Point Vertex ◽  
Nonperturbative Qcd

We discuss the essence of the zero-point in fixed-point gauge of nonperturbative QCD and describe how to set the zero-point appropriately in deriving the nonperturbative quark–gluon three-point vertex functions including gluon condensates.

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