TY - JOUR

T1 - Gravitational waves induced by scalar-tensor mixing

AU - Bari, Pritha

AU - Bartolo, Nicola

AU - Domènech, Guillem

AU - Matarrese, Sabino

N1 - Funding Information: We would like to thank J. L. Bernal, A. Caravano, E. Komatsu, A. Ricciardone, F. Schmidt, and M. Sasaki for valuable discussions. G. D. is supported by the DFG under the Emmy-Noether program Grant No. DO 2574/1-1, Project Number 496592360. Calculations of the scalar-scalar induced GW spectrum have been done with sigw fast . P. B. acknowledges funding from Italian Ministry of Education, University and Research (MIUR) through the “Dipartimenti di eccellenza” project Science of the Universe. P. B., N. B., and S. M. acknowledge support from the Cosmic Orbital and Suborbital Microwave Observations (COSMOS) network () through the ASI (Italian Space Agency) Grants 2016-24-H.0, 2016-24-H.1-2018, and 2020-9-HH.0. For N. B. and S. M., it is a pleasure to recall that some preliminary notes about the GWs propagation including scalar and tensor perturbations at second-order, on which the starting of this project was based, were already shared with Lev Kofman during a visit at the Physics Department of Padova.

PY - 2024/1/9

Y1 - 2024/1/9

N2 - This paper explores the physics of second-order gravitational waves (GWs) induced by scalar-tensor perturbation interactions in the radiation-dominated Universe. We investigate the distinctive signatures of these GWs and their detectability compared to scalar-induced GWs. Unlike scalar-scalar induced GWs, scalar-tensor induced GWs do not present resonances or a logarithmic running in the low frequency tail in the case of peaked primordial spectra. But, interestingly, they partly inherit any primordial parity violation of tensor modes. We find that chirality in primordial GWs can lead to distinguishing effects in scalar-tensor induced GWs in the ultraviolet (UV) region. We also address a potential divergence in our GWs and explore possible solutions. This study contributes to our understanding of GWs in the early Universe and their implications for cosmology and GWs detection.

AB - This paper explores the physics of second-order gravitational waves (GWs) induced by scalar-tensor perturbation interactions in the radiation-dominated Universe. We investigate the distinctive signatures of these GWs and their detectability compared to scalar-induced GWs. Unlike scalar-scalar induced GWs, scalar-tensor induced GWs do not present resonances or a logarithmic running in the low frequency tail in the case of peaked primordial spectra. But, interestingly, they partly inherit any primordial parity violation of tensor modes. We find that chirality in primordial GWs can lead to distinguishing effects in scalar-tensor induced GWs in the ultraviolet (UV) region. We also address a potential divergence in our GWs and explore possible solutions. This study contributes to our understanding of GWs in the early Universe and their implications for cosmology and GWs detection.

UR - http://www.scopus.com/inward/record.url?scp=85182349003&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2307.05404

DO - 10.48550/arXiv.2307.05404

M3 - Article

AN - SCOPUS:85182349003

VL - 109

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 2

M1 - 023509

ER -