Joint analysis of Higgs boson decays and electroweak precision observables in the standard model with a sequential fourth generation.
Joint analysis of Higgs boson decays and electroweak precision observables in the standard model with a sequential fourth generation.
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DOI：
10.1103/physrevd.86.013011
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发表时间：
2012-04
影响因子：
5
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
假设狄拉克中微子和希格斯粒子质量为 125 GeV，我们分析了大型强子对撞机 (LHC) 和 Tevatron 希格斯粒子数据对连续第四代标准模型可行性的影响。为此，我们对 LHC 上的 pp→H→γγ、ZZ*、WW* 的信号横截面、Tevatron 上的 pṕ→VH→Vbb́ (V=W, Z) 以及电弱精密可观测量进行组合拟合。将第四代下型夸克 b′ 的质量固定为 600 GeV，我们发现其他第四代费米子质量的最佳拟合值为 mt′=632 GeV、ml4=113.6 GeV 和 mν4=58.0 GeV。我们比较了三代和四代情况下不同可观测量的 χ2 值和拉力，结果表明三代标准模型可以更好地描述数据。我们还研究了第三代和第四代夸克之间的混合以及未来增加的下限对第四代带电轻子质量 250 GeV 的影响。
We analyze the impact of LHC and Tevatron Higgs data on the viability of the standard model with a sequential fourth generation, assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal cross sections of pp→H→γγ, ZZ∗, WW∗ at the LHC, to pp¯→VH→Vbb¯ (V=W, Z) at the Tevatron and to the electroweak precision observables. Fixing the mass of the fourth-generation down-type quark b′ to 600 GeV we find best-fit values of mt′=632 GeV, ml4=113.6 GeV and mν4=58.0 GeV for the other fourth-generation fermion masses. We compare the χ2 values and pulls of the different observables in the three- and four-generation case and show that the data is better described by the three-generation standard model. We also investigate the effects of mixing between the third- and fourth-generation quarks and of a future increased lower bound on the fourth-generation charged lepton mass of 250 GeV.