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arXiv 1002.0343hep-ph
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Lee-Wick标准模型中的保管同位旋破坏

Custodial Isospin Violation in the Lee-Wick Standard Model

R. Sekhar Chivukula, Arsham Farzinnia, Roshan Foadi, Elizabeth H. Simmons

摘要:

通过计算树能级和费米子单圈对LEP后电弱参数和Zbb耦合的贡献,分析了Lee-Wick标准模型中自然性和同位旋破坏之间的张力.当规范玻色子和费米子的LW伙伴是轻的时,模型是最自然的,但是小的伙伴质量可以导致大的同位旋破坏。后LEP参数在LW SM中产生一个简单的图像:规范扇区仅对Y和W有贡献,主要贡献出现在树级,而费米子扇区仅对S-hat和T-hat有贡献,主要修正出现在一个循环。因此,W和Y限制了LW规范玻色子的质量,使其在95%CL时满足M1,M2 > 2.4 TeV。同样地,T帽的实验极限显示,如果希格斯质量轻,则LW费米子的质量必须满足Mq,Mt > 1.6 TeV(95% CL),如果希格斯质量重,则倾向于排除任何LW费米子质量的LW SM。顶夸克对Zbb耦合的贡献可能更加严格,在95%CL时,LW费米子质量的下限为4 TeV。

英文摘要:

We analyze the tension between naturalness and isospin violation in the Lee-Wick Standard Model (LW SM), by computing tree-level and fermionic one-loop contributions to the post-LEP electroweak parameters and the Zbb coupling. The model is most natural when the LW partners of the gauge bosons and fermions are light, but small partner masses can lead to large isospin violation. The post-LEP parameters yield a simple picture in the LW SM: the gauge sector contributes to Y and W only, with leading contributions arising at tree-level, while the fermion sector contributes to S-hat and T-hat only, with leading corrections arising at one loop. Hence, W and Y constrain the masses of the LW gauge bosons to satisfy M1, M2 > 2.4 TeV at 95% CL. Likewise, experimental limits on T-hat reveal that the masses of the LW fermions must satisfy Mq, Mt > 1.6 TeV at 95% CL if the Higgs mass is light and tend to exclude the LW SM for any LW fermion masses if the Higgs mass is heavy. Contributions from the top-quark sector to the Zbb coupling can be even more stringent, placing a lower bound of 4 TeV on the LW fermion masses at 95% CL.

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