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arXiv 0905.2559hep-ph
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单重态Majoron模型中的电弱相变和LHC特征

Electroweak Phase Transition and LHC Signatures in the Singlet Majoron Model

James M. Cline, Sabine Kraml, Guillaume Laporte, Hiroki Yamashita

摘要:

我们重新考虑的强度的电弱相变在单重态Majoron扩展的标准模型,与低(~TeV)规模的单重态VEV。在参数空间的相当大的区域内,我们发现了一个强烈的一级相变,这是电弱重子生成所感兴趣的,特别是当单重态和二重态希格斯粒子之间的交叉耦合lambda_{hs} |S| ^2 |H| ^2很显著的时候。单重态中微子的大的Majorana Yukawa耦合y_i S nu_i^c nu_i对加强跃迁也很重要。我们将LEP和Tevatron的希格斯质量的约束,和电弱精度的约束,在我们的搜索允许的参数,成功的例子包括单重质量范围从5 GeV到几个TeV。具有强相变的模型通常预测非标准希格斯粒子的质量在113 GeV < m_H < 200 GeV的范围内,并且由于与单线态混合,产生的截面减小,cos^2(θ)显著小于1。我们还发现了一些例子,其中单线态是轻的,衰变H -> SS可以修改希格斯分支比相对于标准模型的预期。

英文摘要:

We reconsider the strength of the electroweak phase transition in the singlet Majoron extension of the Standard Model, with a low (~TeV) scale of the singlet VEV. A strongly first order phase transition, of interest for electroweak baryogenesis, is found in sizeable regions of the parameter space, especially when the cross-coupling lambda_{hs}|S|^2|H|^2 between the singlet and the doublet Higgs is significant. Large Majorana Yukawa couplings of the singlet neutrinos, y_i S nu_i^c nu_i, are also important for strengthening the transition. We incorporate the LEP and Tevatron constraints on the Higgs masses, and electroweak precision constraints, in our search for allowed parameters; successful examples include singlet masses ranging from 5 GeV to several TeV. Models with a strong phase transition typically predict a nonstandard Higgs with mass in the range 113 GeV < m_H < 200 GeV and production cross sections reduced by mixing with the singlet, with cos^2(theta) significantly less than 1. We also find examples where the singlet is light and the decay H -> SS can modify the Higgs branching ratios relative to Standard Model expectations.

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