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Perturbative $S$-matrix unitarity ($S^{dagger}S=1$) in $R_{mu u} ^2$ gravity

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 نشر من قبل Keisuke Izumi
 تاريخ النشر 2020
  مجال البحث فيزياء
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We show that in the quadratic curvature theory of gravity, or simply $R_{mu u} ^2$ gravity, the tree-level unitariy bound (tree unitarity) is violated in the UV region but an analog for $S$-matrix unitarity ($SS^{dagger} = 1$) is satisfied. This theory is renormalizable, and hence the failure of tree unitarity is a counter example of Llewellyn Smiths conjecture on the relation between them. We have recently proposed a new conjecture that $S$-matrix unitarity gives the same conditions as renormalizability. We verify that $S$-matrix unitarity holds in the matter-graviton scattering at tree level in the $R_{mu u} ^2$ gravity, demonstrating our new conjecture.



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