The covariant theory of strong interaction symmetries

1965 ◽  
Vol 284 (1396) ◽  
pp. 146-158 ◽  
Keyword(s):  
Irreducible Representation ◽  
Form Factors ◽  
Positive Energy ◽  
Electromagnetic Form Factors ◽  
Covariant Theory ◽  
Relativistic Generalization ◽  
Rest System ◽  
Symmetry Scheme ◽  
The Mean

A classification of particles is suggested based on a Ũ (12) symmetry scheme. This is a relativistic generalization of the U (6) symmetry. The spin 1 2 and 3 2 baryons are each described by 20-component spinors which satisfy Bargmann-Wigner equations and belong to the 3̲6̲4̲ representation of the Ũ (12) group while the vector and p. s. mesons belong to the representation 1̲4̲3̲. The procedure for writing fully relativistic form factors is worked out in detail for baryon-meson and meson-meson cases. The new results are the following: (1) F C ( q 2 ) F M ( q 2 ) ∝ 1 + q 2 < 2 μ > m , Where F c and F M are (Sachs) electromagnetic form factors. (2) μ D = 1 + 2 m /< μ >, where < μ > is the mean mass of the 1 - multiplet and m the nucleon mass. (3) μ ρ,K* = 3. The conventional U (6) results can be recovered by projecting to the positive energy subspace in the rest system for each particle. To any irreducible representation of the U (6) there corresponds one irreducible representation of Ũ (12) and vice versa.

scholarly journals Hyperon electromagnetic form factors in the timelike region

2021 ◽  
Vol 103 (1) ◽  
Author(s):  
Johann Haidenbauer ◽  
Ulf-G. Meißner ◽  
Ling-Yun Dai
Keyword(s):  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Timelike Region

scholarly journals Covariant nucleon electromagnetic form factors from the Goldstone-boson-exchange quark model

2001 ◽  
Vol 511 (1) ◽  
pp. 33-39 ◽  
Author(s):  
R.F. Wagenbrunn ◽  
S. Boffi ◽  
W. Klink ◽  
W. Plessas ◽  
M. Radici
Keyword(s):  
Quark Model ◽  
Goldstone Boson ◽  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Boson Exchange

The electromagnetic form factors of the proton and quantum chromodynamics

1978 ◽  
Vol 74 (1-2) ◽  
pp. 105-107 ◽  
Author(s):  
Robert Coquereaux ◽  
Eduardo de Rafael
Keyword(s):  
Quantum Chromodynamics ◽  
Form Factors ◽  
Electromagnetic Form Factors

Split spinal cord malformations in children

1998 ◽  
Vol 88 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Yusuf Ersşahin ◽  
Saffet Mutluer ◽  
Sevgül Kocaman ◽  
Eren Demirtasş
Keyword(s):  
Spinal Cord ◽  
Neurological Deficits ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Content Type ◽  
Spinal Lesion ◽  
The Mean ◽  
Fine Print

Object. The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Methods. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. Conclusions. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients. The risk of neurological deficits resulting from SSCMs increases with the age of the patient; therefore, all patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations.

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