AT4 - Massive gravity, Horndeski theory and other "ghost-free" models of modified gravity |
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Speaker |
Hirano, Shin'ichi |
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Coauthors |
Tsutomu Kobayashi, Hiroyuki Tashiro, Shuichiro Yokoyama |
| Talk Title |
Matter bispectrum beyond Horndeski |
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Abstract |
The Horndeski scalar-tensor theory and its recent extensions allow nonlinear derivative interactions of the scalar degree of freedom. We study the matter bispectrum of large scale structure as a probe of these modified gravity theories, focusing in particular on the effect of the terms that newly appear in the so-called "beyond Horndeski" theories. We derive the second-order solution for the matter density perturbations and find that the interactions beyond Horndeski lead to a new time-dependent coefficient in the second-order kernel which differs in general from the standard value of general relativity and the Horndeski theory. This can deform the matter bispectrum at the folded triangle configurations ($k_1+k_2=k_3$), while it is never possible within the Horndeski theory. |
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Talk view |
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