@article{oai:nagoya.repo.nii.ac.jp:02001714,
 author = {Abe, Yugo and Inami, Takeo and Izumi, Keisuke},
 issue = {16},
 journal = {Modern Physics Letters A},
 month = {May},
 note = {We show that in the quadratic curvature theory of gravity, or simply R^2μν gravity, the tree-level unitarity bound (tree unitarity) is violated in the UV region but an analog for S-matrix unitarity (SS^†=1) is satisfied. This theory is renormalizable, and hence the failure of tree unitarity is a counter example of Llewellyn Smith’s 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 the tree level in the R^2μν gravity, demonstrating our new conjecture.},
 title = {Perturbative S-matrix unitarity (S^†S = 1) in R^2μν gravity},
 volume = {36},
 year = {2021}
}