Experiments That can Determine Whether Pions and Kaons are Spin-0 Vector Particles

I am going to discuss experiments with the potential to prove that the pion and kaon are vector particles. The motivation is intriguing results of several experiments conducted during the late 1950s and early 1960s that strongly imply that pions and kaons carry directional information. These experiments were performed by five distinct research groups and demonstrated that pions possess directional attributes with a statistical uncertainty of less than 1 in 2500 in each experiment. During the 1950s and 1960s, the prevailing scientific consensus held that a particle could only be classified as a vector particle if it exhibited spin equal to 1.  However, it was firmly established that pions possess spin equal to 0, leading many scientists to overlook the observed pi-mu asymmetry results. More recently, it has been shown that a spin-0 particle can indeed be a vector [1]. The proposed pion experiments depart from those conducted in the 1950s and 1960s because they involve the variation of the angle between the pion's polarization vector and its momentum vector using a magnetic field (which does not affect the polarization direction due to the pion's spin zero). One observes how the muon distribution changes as the pion's direction is varied. Additionally, given the compelling evidence of directional information in kaons, it is imperative to investigate potential asymmetries in the decay process K+ -> mu+ + neutrino.

 

[1] W. A. Perkins, "Massive vector particles with spin zero," EPL (Europhysics Letters) 114 (2016) 41002.