Some field-theoretical aspects of two types of the Poincare group representations

Abstract: The capabilities of some approaches to the relativistic description of hadronic states with any rest spin are analysed. The key feature in the Wigner's construction of irreducible representations of the Poincare group which makes this construction fruitless in the particle physics is picked out. A realization of unitary irreducible representations of the Poincare group of the standard type, which yet have never been considered, is discussed. The viability of the description of hadrons by the Poincare group representations of the standard type in the space of the infinite-component ISFIR-class fields is pointed out.