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arXiv · hep-ph/0404023

Wrong-Helicity Electrons in Radiative Muon Decay

V. S. Schulz·L. M. Sehgal
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Abstract

We have studied in detail the spectrum of the decay mu^- -> e^- anti-nu_e nu_mu gamma as a function of the electron helicity, and verify the prediction of Sehgal (Phys.Lett. B569, 25 (2003)) that a significant fraction of the electrons in this decay is right-handed. These ``wrong-helicity'' electrons persist in the limit lambda = m_e / m_mu -> 0, and are connected with helicity-flip bremsstrahlung in QED. The longitudinal polarization of the electron is calculated as a function of the photon and electron energy, and deviates systematically from the naive V-A prediction P_L = -1. The right-handed component is concentrated in the collinear region theta <= m_e / E_e. In the limit lambda -> 0, we reproduce the results obtained in (Phys.Lett. B569, 25 (2003)) using the helicity-flip splitting function introduced by Falk and Sehgal.

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V. S. Schulz, L. M. Sehgal. 2004-05-10. Wrong-Helicity Electrons in Radiative Muon Decay. https://doi.org/10.1016/j.physletb.2004.05.015

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