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arXiv · 1805.10963

Ghost-free scalar-fermion interactions

Rampei Kimura·Yuki Sakakihara·Masahide Yamaguchi
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Abstract

We discuss a covariant extension of interactions between scalar fields and fermions in a flat space-time. We show, in a covariant theory, how to evade fermionic ghosts appearing because of the extra degrees of freedom behind a fermionic nature even in the Lagrangian with first derivatives. We will give a concrete example of a quadratic theory with up to the first derivative of multiple scalar fields and a Weyl fermion. We examine not only the maximally degenerate condition, which makes the number of degrees of freedom correct, but also a supplementary condition guaranteeing that the time evolution takes place properly. We also show that proposed derivative interaction terms between scalar fields and a Weyl fermion cannot be removed by field redefinitions.

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Rampei Kimura, Yuki Sakakihara, Masahide Yamaguchi. 2018-08-25. Ghost-free scalar-fermion interactions. https://doi.org/10.1103/physrevd.98.044043

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