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arXiv 1703.09237hep-ph
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在全单圈水平上两体部分衰变宽度的一般计算

Generic calculation of two-body partial decay widths at the full one-loop level

Mark D. Goodsell, Stefan Liebler, Florian Staub

摘要:

我们描述了一个完全通用的实现两体部分衰变宽度在完整的一个循环水平的SARAH和SPheno框架兼容的最支持的模型。它包括费米子衰变为费米子和标量或规范玻色子,以及标量衰变为两个费米子,两个规范玻色子,两个标量或一个标量和一个规范玻色子。我们提出了相关的通用表达式为虚拟和真实的更正。而波函数修正是从壳层条件确定的,底层模型的参数默认在DR(或MS)方案中重新归一化。但是,用户也可以定义特定于模型的计数项。作为一个例子,我们讨论了标准模型中顶夸克衰变的汤姆逊极限下电荷的重整化。单圈诱导衰变也得到支持。该框架还允许增加质量和混合校正诱导在更高的订单所涉及的外部状态。我们解释我们的程序,以取消红外发散的情况下,这是通过红外计数器项考虑到校正戈德斯通玻色子顶点。我们比较我们的结果sfermion,胶子和希格斯衰变的最小超对称标准模型(MSSM)对公共代码SFOLD,FVSFOLD和HFOLD和解释观察到的差异。辐射诱导的胶子和中性子衰变进行了比较,对原来的实施SPHENO在MSSM。我们精确地再现了程序CNNDecays在R宇称破坏模型中对中性伴子和电荷伴子衰变的计算结果。新版本SARAH 4.11.0默认包括在完整的单圈水平上计算两体衰变宽度。描述了某些模型类的当前限制。

英文摘要:

We describe a fully generic implementation of two-body partial decay widths at the full one-loop level in the SARAH and SPheno framework compatible with most supported models. It incorporates fermionic decays to a fermion and a scalar or a gauge boson as well as scalar decays into two fermions, two gauge bosons, two scalars or a scalar and a gauge boson. We present the relevant generic expressions for virtual and real corrections. Whereas wavefunction corrections are determined from on-shell conditions, the parameters of the underlying model are by default renormalised in a DR (or MS) scheme. However, the user can also define model-specific counter-terms. As an example we discuss the renormalisation of the electric charge in the Thomson limit for top-quark decays in the standard model. One-loop induced decays are also supported. The framework additionally allows the addition of mass and mixing corrections induced at higher orders for the involved external states. We explain our procedure to cancel infra-red divergences for such cases, which is achieved through an infra-red counter-term taking into account corrected Goldstone boson vertices. We compare our results for sfermion, gluino and Higgs decays in the minimal supersymmetric standard model (MSSM) against the public codes SFOLD, FVSFOLD and HFOLD and explain observed differences. Radiative induced gluino and neutralino decays are compared against the original implementation in SPheno in the MSSM. We exactly reproduce the results of the code CNNDecays for decays of neutralinos and charginos in R-parity violating models. The new version SARAH 4.11.0 by default includes the calculation of two-body decay widths at the full one-loop level. Current limitations for certain model classes are described.

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