Impact of a Higgs boson at a mass of 126 GeV on the standard model with three and four fermion generations.
Impact of a Higgs boson at a mass of 126 GeV on the standard model with three and four fermion generations.
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DOI：
10.1103/physrevlett.109.241802
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发表时间：
2012-09
影响因子：
8.6
通讯作者：
O. Eberhardt;G. Herbert;H. Lacker;A. Lenz;A. Menzel;U. Nierste;M. Wiebusch
中科院分区：
文献类型：
--
作者：
O. Eberhardt;G. Herbert;H. Lacker;A. Lenz;A. Menzel;U. Nierste;M. Wiebusch
我们使用LHC和Tevatron的最新Higgs搜索结果，LEP和SLD测量的电弱精密观测量以及M（W），m（t）和α（s）的最新测定，对三代和四代标准模型（SM）进行了全面的统计分析。对于三代的情况下，我们分析的张力在电弱拟合删除个别可观的拟合和比较其预测值与测量值。特别是，我们讨论了希格斯粒子的搜索结果的电弱精密观测量从他们的最佳拟合值的偏差的影响。我们对顶质量的间接预测是m（t）=175.7（-2.2）（+3.0）GeV，在68.3% C. L.，这与直接测量结果非常一致。我们还在M（W）-m（t）平面中绘制了优选面积。最适合的希格斯玻色子质量是126.0 GeV。对于具有微扰连续第四代费米子（SM 4）的SM的情况下，我们讨论了希格斯信号强度与其最佳拟合值的偏差。H → γγ信号强度现在在大于4σ时与其最佳拟合SM 4值不一致。我们进行似然比检验来比较SM和SM 4，并表明SM 4在5.3σ处被排除。没有关于H → bb的Tevatron数据，显著性下降到4.8σ。
We perform a comprehensive statistical analysis of the standard model (SM) with three and four generations using the latest Higgs search results from LHC and Tevatron, the electroweak precision observables measured at LEP and SLD, and the latest determinations of M(W), m(t), and α(s). For the three-generation case we analyze the tensions in the electroweak fit by removing individual observables from the fit and comparing their predicted values with the measured ones. In particular, we discuss the impact of the Higgs search results on the deviations of the electroweak precision observables from their best-fit values. Our indirect prediction of the top mass is m(t) =175.7(-2.2)(+3.0) GeV at 68.3% C.L., which is in good agreement with the direct measurement. We also plot the preferred area in the M(W)-m(t) plane. The best-fit Higgs boson mass is 126.0 GeV. For the case of the SM with a perturbative sequential fourth fermion generation (SM4) we discuss the deviations of the Higgs signal strengths from their best-fit values. The H → γγ signal strength now disagrees with its best-fit SM4 value at more than 4σ. We perform a likelihood-ratio test to compare the SM and SM4 and show that the SM4 is excluded at 5.3σ. Without the Tevatron data on H → bb the significance drops to 4.8σ.