Wigner’s classification of particles in 1939 contains a type of particles (bosons or fermions with unbounded helicity, called by us simply Wigner particles (WP), routinely dismissed in the textbooks, in spite of having perfectly positive energy. A reason for that may be a no-go theorem by Yngvason’s theorem in the seventies: no local quantum fields on a Fock space can be associated to them. However, Yngvason himself later proved that string-local quantum fields can accommodate the WP.
Starting with the papers by Schuster and Toro in 2013, in recent times there has been a renewal of interest in the WP. In particular, a construction of string-local quantum fields for them has been given recently by Rehren [JHEP 1711, 130 (2017)]. The constructions so far partake of the complications of high-spin theory, overlooking peculiar kinematical properties of the WP. Reaching back to old work by Wigner and Bargmann, we present for them an alternative first-quantized formalism, of surprising simplicity.