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arXiv 1404.0175hep-ph
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实单重标量对Veltman条件的影响

Effects of a Real Singlet Scalar on Veltman Condition

Canan Nurhan Karahan, Beste Korutlu

摘要:

我们重新讨论了标准模型(SM)中的微调问题,并利用一个带有一个实SM规范单重标量场的最小扩展粒子谱,给出了在Veltman条件下的修正.我们要求新的标量只通过Higgs门与SM场相互作用,并且新的单态获得真空期望值,导致与SM中Higgs偶重态的CP偶中性分量混合。混合角的实验界限由观察到的最佳拟合信号强度$σ/σ_{\rm SM}$确定。虽然用紫外截止尺度$Λ$计算的对希格斯质量平方的单圈辐射修正带有负系数,但对单重态质量平方的量子修正根据所选的参数空间获得正值和负值,如果是正值,则可以通过引入单重态或二重态矢量费米子来消除。然而,基于标量之间存在混合的事实,当转换为物理状态时,希格斯场与矢量类费米子的树级耦合恶化了希格斯质量等级问题。因此,如果标量之间存在混合,那么通常试图引入类矢量费米子来抵消新标量质量中的发散可能不是一个解决方案。

英文摘要:

We revisit the fine-tuning problem in the Standard Model (SM) and show the modification in Veltman condition by virtue of a minimally-extended particle spectrum with one real SM gauge singlet scalar field. We demand the new scalar to interact with the SM fields through Higgs portal only, and that the new singlet to acquire a vacuum expectation value, resulting in a mixing with the CP-even neutral component of the Higgs doublet in the SM. The experimental bounds on the mixing angle are determined by the observed best-fit signal strength $σ/σ_{\rm SM}$. While, the one-loop radiative corrections to the Higgs mass squared, computed with an ultraviolet cut-off scale $Λ$, comes with a negative coefficient, the quantum corrections to the singlet mass squared acquires both positive and negative values depending on the parameter space chosen, which if positive might be eliminated by introducing singlet or doublet vector-like fermions. However, based upon the fact that there is mixing between the scalars, when transformed into the physical states, the tree-level coupling of the Higgs field to the vector-like fermions worsen the Higgs mass hierarchy problem. Therefore, the common attempt to introduce vector-like fermions to cancel the divergences in the new scalar mass, might not be a solution, if there is mixing between the scalars.

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