Semirelativistic approximation to the γ N → N ( 1520 ) and γ N → N ( 1535 ) transition form factors

The representation of the wave functions of the nucleon resonances within a relativistic framework is a complex task. In a nonrelativistic framework the orthogonality between states can be imposed naturally. In a relativistic generalization, however, the derivation of the orthogonality condition bet...

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Bibliographic Details
Published in:Physical review. D 2017-03, Vol.95 (5), p.054008, Article 054008
Main Author: Ramalho, G.
Format: Article
Language:English
Subjects:
Approximation
Form factors
Mathematical analysis
Momentum transfer
Orthogonality
Quarks
Relativism
Relativistic effects
Wave functions
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Summary:The representation of the wave functions of the nucleon resonances within a relativistic framework is a complex task. In a nonrelativistic framework the orthogonality between states can be imposed naturally. In a relativistic generalization, however, the derivation of the orthogonality condition between states can be problematic, particularly when the states have different masses. In this work we study the N(1520) and N(1535) states using a relativistic framework. We considered wave functions derived in previous works, but impose the orthogonality between the nucleon and resonance states using the properties of the nucleon, ignoring the difference of masses between the states (semirelativistic approximation). The N(1520) and N(1535) wave functions are then defined without any adjustable parameters and are used to make predictions for the valence quark contributions to the transition form factors. The predictions compare well with the data particularly for high momentum transfer, where the dominance of the quark degrees of freedom is expected.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.95.054008