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arXiv 1404.2640hep-ph
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Georgi-Machacek模型中的解耦极限

The decoupling limit in the Georgi-Machacek model

Katy Hartling, Kunal Kumar, Heather E. Logan

摘要:

我们研究了Georgi-Machacek模型中最一般的标量势,该模型以保持SU(2)对称性的方式将同位旋三重态标量加入到标准模型中。我们表明,该模型具有一个去耦极限,其中占主导地位的三重态变得沉重和简并,而其余的轻中性标量的耦合接近的SM希格斯玻色子玻色子。我们发现类SM的希格斯玻色子与费米子对和规范玻色子对的耦合可以偏离它们的SM值,修正值可以达到$\mathcal{O}(v^2/M_{\rm new}^2)$,其中$v$是SM的Higgs真空期望值,$M_{\rm new}$是主要三重态的质量标度。特别是,与$W$和$Z$玻色子对的类SM希格斯玻色子耦合可以比在两个希格斯双重模型中更慢地解耦,在两个希格斯双重模型中,它们偏离它们的SM值,如$\mathcal{O}(v^4/M_{\rm new}^4)$。此外,在退耦极限附近,类SM希格斯玻色子与$W$和$Z$对的耦合总是大于它们的SM值,而这在两个Higgs双态模型中是不可能出现的。因此,精确测量Higgs与$W$和$Z$对的耦合可以提供区分Georgi-Machacek模型和两个Higgs双重模型的有效方法。数值扫描表明,当能量为800~GeV时,$M_{\rm new}$的耦合偏差可达10%.

英文摘要:

We study the most general scalar potential of the Georgi-Machacek model, which adds isospin-triplet scalars to the Standard Model (SM) in a way that preserves custodial SU(2) symmetry. We show that this model possesses a decoupling limit, in which the predominantly-triplet states become heavy and degenerate while the couplings of the remaining light neutral scalar approach those of the SM Higgs boson. We find that the SM-like Higgs boson couplings to fermion pairs and gauge boson pairs can deviate from their SM values by corrections as large as $\mathcal{O}(v^2/M_{\rm new}^2)$, where $v$ is the SM Higgs vacuum expectation value and $M_{\rm new}$ is the mass scale of the predominantly-triplet states. In particular, the SM-like Higgs boson couplings to $W$ and $Z$ boson pairs can decouple much more slowly than in two Higgs doublet models, in which they deviate from their SM values like $\mathcal{O}(v^4/M_{\rm new}^4)$. Furthermore, near the decoupling limit the SM-like Higgs boson couplings to $W$ and $Z$ pairs are always larger than their SM values, which cannot occur in two Higgs doublet models. As such, a precision measurement of Higgs couplings to $W$ and $Z$ pairs may provide an effective method of distinguishing the Georgi-Machacek model from two Higgs doublet models. Using numerical scans, we show that the coupling deviations can reach 10% for $M_{\rm new}$ as large as 800~GeV.

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