5 papers
Testing gravitational wave polarizations with LISA
Shingo Akama, Maxence Corman, Paola C. M. Delgado +16
In this paper we quantify the ability of the Laser Interferometer Space Antenna (LISA) to test the presence of non-tensorial polarizations as well as modifications to the tensor on…
Bypassing the Lyth Bound with Entangled Gravitons: Primordial Signatures and Late-Time Noise
Shingo Akama, Chunshan Lin
We demonstrate that quantum entanglement between primordial gravitons in dynamically decoupled gravitational sectors can parametrically enhance the tensor power spectrum during inf…
Scalar parity-odd trispectrum from gravitational Chern-Simons interaction vertices
Giorgio Orlando, Shingo Akama, Chunshan Lin
In this paper, we explore parity violation in a scalar trispectrum from a dynamical Chern-Simons gravity theory. So far, a graviton-mediated diagram with two vertexes being of gene…
Stochastic gravitational wave background anisotropies from inflation with non-Bunch-Davies states
Shingo Akama, Shin'ichi Hirano, Shuichiro Yokoyama
It is known that stochastic gravitational wave backgrounds (SGWBs) have anisotropies generated by squeezed-type tensor non-Gaussianities originating from scalar-tensor-tensor (STT)…
Primordial full bispectra from the general bounce cosmology
Shingo Akama
Primordial non-Gaussianities are key quantities to test early universe scenarios. In this paper, we compute full bispectra of scalar and tensor perturbations generated during a con…