The effect of the polarization of the vacuum in magnetic fields not too far below $B_c=\frac{{m_e}^2{c}^3}{e\hslash }=4.4\mathrm{}\times {10}^{13}$ G on the polarization and transport of the radiation in plasma is discussed, and found to be significant. The expressions for the cross sections of all radiative processes are altered thereby. We present a calculation of the Thomson cross section, in which inclusion of vacuum effects leads to well-marked departures from previously computed behavior. These effects should lead to possible observable consequences in pulsars.

• Received 26 July 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.1544