Radiation Accompanying Meson Creation

Electromagnetic radiation is expected to accompany the creation of charged mesons in nucleon-nucleon collisions. The amount and character of this radiation is calculated for mesons of spin 0, $\frac{1}{2}\hslash$, and $\hslash$, in each case with normal magnetic moment. The ratio of radiated energy to initial meson energy increases logarithmically for high meson energy in the first two cases, and is of the order of 1 percent for the highest energies of interest in cosmic radiation. For vector (spin $\hslash$) mesons, this ratio is $\left(\frac{11\alpha }{4860\pi }\right){\left(\frac{E}{m{c}^2}\right)}^4$ in the relativistic region, where $\alpha$ is the fine-structure constant, and $m$ and $E$ are the rest mass and the initial energy of the meson in the coordinate system in which the center of mass of the colliding nucleons is at rest. This is so large at high energies that the assumption that $\pi$-mesons have spin $\hslash$ would, with a plausible theory of the multiplicity of meson production, account for the observation of soft radiation in conjunction with energetic nuclear events.