We present a comprehensive study on Formula: see text and Formula: see text groups, their representations and algebraic aspects. These groups, together with Formula: see text, arise as the symmetry groups of Very Special Relativity (VSR), where full Lorentz invariance is reduced while retaining many relativistic consequences. After obtaining Formula: see text through the Inönü-Wigner contraction procedure, a complete four-dimensional algebraic representation is shown for Formula: see text and Formula: see text. Besides that, we apply Bargmann’s formalism to investigate the (projective) representations for both cases, keeping track of the source of phase factors. We complete the study by presenting a particularly simple analysis to probe the existence of local phase factors, which is useful when dealing with non-abelian groups.
Rodrigues et al. (Fri,) studied this question.