Bian Ligong, Liu Tao, Shu Jing
State Key Laboratory of Theoretical Physics and Kavli Institute for Theoretical Physics China, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Phys Rev Lett. 2015 Jul 10;115(2):021801. doi: 10.1103/PhysRevLett.115.021801.
We present a class of cancellation conditions for suppressing the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). Such a cancellation is of particular significance after the new eEDM upper limit was released by the ACME Collaboration, which strongly constrains the allowed magnitude of CP violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG). Explicitly, if both the CP-odd Higgs-photon-photon (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of CP-even and CP-odd Higgs bosons. With a cancellation, large CP violation in the Higgs sector is still allowed, yielding successful EWBG. The reopened parameter regions would be probed by future neutron, mercury EDM measurements, and direct measurements of Higgs CP properties at the Large Hadron Collider Run II and future colliders.
我们提出了一类用于抑制巴尔-泽图对电子电偶极矩（eEDM）总贡献的抵消条件。在ACME合作组发布新的eEDM上限之后，这种抵消具有特别重要的意义，该上限强烈限制了希格斯耦合中CP破坏的允许幅度，从而限制了电弱重子生成（EWBG）的可行性。具体而言，如果CP奇的希格斯-光子-光子（Z玻色子）和CP奇的希格斯-电子-正电子耦合都开启，那么在CP混合希格斯玻色子的贡献之间（其他希格斯玻色子解耦），或者在CP偶和CP奇希格斯玻色子的贡献之间，可能会发生抵消。通过这种抵消，希格斯扇区中仍然允许存在较大的CP破坏，从而实现成功的EWBG。重新开放的参数区域将由未来的中子、汞电偶极矩测量，以及在大型强子对撞机运行II和未来对撞机上对希格斯CP性质的直接测量来探测。
