Perturbativity constraints in BSM models
Perturbativity constraints in BSM models
复制标题
BSM 模型中的扰动约束
DOI：
10.1140/epjc/s10052-018-5676-5
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
F. Staub
中科院分区：
文献类型：
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作者：
M. Krauss;F. Staub
针对标准模型的非超对称扩展进行的现象学研究通常使用树级参数作为输入来定义模型的标量扇区。这隐含地假设标量扇区的完整壳内计算是可能的，并且是有意义的。然而，情况不一定是这样，正如我们在 Georgi-Machacek 模型的示例中明确显示的那样。该模型具有吸引人的保管对称性，可以解释 $$\rho $$ρ 参数的小值。然而，在不破坏保管对称性的情况下，模型无法在壳上重整。此外，我们发现，经常会发生辐射校正如此之大，以至于任何基于微扰展开的考虑似乎都毫无意义：四次耦合的反项可能变得比 $$4\pi $$4π 大得多，和/或二环质量校正可能变得比单环质量校正大。因此，有必要条件来挑选出不能进行扰动处理的参数区域。我们提出并讨论了不同的扰动条件集，并展示了它们对 Georgi-Machacek 模型参数空间的影响。此外，所提出的条件足够通用，也可以应用于其他模型。我们还指出，Georgi-Machacek 模型中的真空稳定性约束迄今为止仅应用于树级别，接受了关键的辐射校正。我们表明，在环路级别具有稳定电弱真空的参数空间的大区域可能会被树级条件错误地排除。
Phenomenological studies performed for non-supersymmetric extensions of the Standard Model usually use tree-level parameters as input to define the scalar sector of the model. This implicitly assumes that a full on-shell calculation of the scalar sector is possible – and meaningful. However, this doesn’t have to be the case as we show explicitly at the example of the Georgi-Machacek model. This model comes with an appealing custodial symmetry to explain the smallness of the $$\rho $$ρ parameter. However, the model cannot be renormalised on-shell without breaking the custodial symmetry. Moreover, we find that it can often happen that the radiative corrections are so large that any consideration based on a perturbative expansion appears to be meaningless: counter-terms to quartic couplings can become much larger than $$4\pi $$4π and/or two-loop mass corrections can become larger than the one-loop ones. Therefore, conditions are necessary to single out parameter regions which cannot be treated perturbatively. We propose and discuss different sets of such perturbativity conditions and show their impact on the parameter space of the Georgi-Machacek model. Moreover, the proposed conditions are general enough that they can be applied to other models as well. We also point out that the vacuum stability constraints in the Georgi-Machacek model, which have so far only been applied at the tree level, receive crucial radiative corrections. We show that large regions of the parameter space which feature a stable electroweak vacuum at the loop level would have been – wrongly – ruled out by the tree-level conditions.
DOI：
10.1140/epjc/s10052-014-3247-y
发表时间：
2014-11
期刊：
The European Physical Journal C
影响因子：
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作者：
M. Goodsell;K. Nickel;F. Staub
通讯作者：
M. Goodsell;K. Nickel;F. Staub
DOI：
10.1140/epjc/s10052-014-2992-2
发表时间：
2014-05
期刊：
The European Physical Journal C
影响因子：
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作者：
W. Porod;F. Staub;A. Vicente
通讯作者：
W. Porod;F. Staub;A. Vicente
DOI：
10.1140/epjc/s10052-017-4893-7
发表时间：
2017-03
期刊：
The European Physical Journal C
影响因子：
--
作者：
F. Staub;W. Porod
通讯作者：
F. Staub;W. Porod