Scattering from electroweak strings

Abstract

The scattering of a charged fermion from an electroweak string is studied. Owing to an amplification of the wave function at the core radius, the cross sections for helicity flip processes can be largely enhanced. For 0<sin2θW<1/2 (where θW is the Weinberg angle), ω∼k∼me, and kR1, we show that the helicity flip differential cross section for electrons is of the order me-1 and is independent of the angle. We compare our results with those obtained in calculations of rates for baryon-number-violating processes in the core of a cosmic string. In that case, while the enhancement is a general phenomenon, its actual magnitude is extremely sensitive to the fractional flux carried by the string core. Apart from showing the existence of a similar enhancement effect for nontopological strings, our results indicate that in some models the magnitude of enhancement can be rendered much less sensitive to the value of the parameters in the theories. Scattering of particles off semilocal strings and axion strings is also considered. © 1995 The American Physical Society.