Top Down Electroweak Dipole Operators
We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark (d_t) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v, the d_t arises from two gauge invariant operators generated at a scale Λ≫v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on |d_t|. Working in the leading log-squared approximation, we find that the present upper bound on |d_t| is 10^(−19) e cm for Λ=1 TeV, except in regions of finely tuned cancellations that allow for |d_t| to be up to fifty times larger. Future d_e and d_n probes may yield an order of magnitude increase in d_t sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.
Additional Information© 2018 The Author(s). Published by Elsevier B.V. under a Creative Commons license - Attribution 4.0 International (CC BY 4.0). Open Access funded by SCOAP³ - Sponsoring Consortium for Open Access Publishing in Particle Physics. Received 19 November 2017, Revised 6 March 2018, Accepted 11 April 2018, Available online 13 April 2018. We are grateful to Jordy de Vries and Adrian Signer for useful discussions and comments. We also thank Patrick Draper and Hiren Patel for having fruitful discussions. KF thanks Natsumi Nagata and Eibun Senaha for valuable discussions. MJRM thanks Haipeng An, Mark B. Wise, and Yue Zhang for several helpful conversations. This work was supported in part under U.S. Department of Energy contract DE-SC0011095.
Published - 1-s2.0-S037026931830306X-main.pdf
Submitted - 1706.08548.pdf