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arXiv 0906.5330hep-phhep-ex
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在LHC上具有μ-τ对称性的两个Higgs双重态III跷跷板

Two Higgs Doublet Type III Seesaw with mu-tau symmetry at LHC

Priyotosh Bandyopadhyay, Sandhya Choubey, Manimala Mitra

备注：
51 pages, 11 tables, 8 figures
发表信息：
JHEP 0910:012,2009
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摘要：

我们提出了一个具有$μ$ - $τ$味对称性的双Higgs二重态III型跷跷板模型.在我们的模型中，我们增加了一个额外的SU（2）希格斯偶态和三个SU（2）费米子三重态。两个希格斯二重态的存在使得在100 GeV质量范围内的三重态费米子与小中微子质量的自然解释成为可能，而不需要将汤川耦合微调到极小的值。三重态费米子耦合到规范玻色子，因此可以在LHC中产生。我们详细研究了这些重奇异费米子的生产和随后的衰变的有效截面。我们第一次表明，$μ$ - $τ$味对称性的低能量中微子质量矩阵的混合矩阵的中性和带电的重费米子是不统一的，并进行味对称模式的结果。这种味道结构可以在LHC的重费米子衰变中观察到。在我们的模型中的大Yukawa耦合导致重费米子衰变成较轻的轻子和希格斯粒子，其衰变率比具有100 GeV三重态费米子的希格斯III型跷跷板模型的衰变率大约$10^{11}$倍。中微子质量小限制了模型中的中性Higgs混合角$\sinα$，使得重费米子衰变为较轻的中性CP偶Higgs $h^0$、CP奇Higgs $A^0$和带电Higgs $H^\pm$，但几乎不衰变为较重的中性CP偶Higgs $H^0$。$\sinα$的小值还导致$h^0$的寿命非常长。这个位移的衰变顶点在LHC上应该是可见的。我们为我们的模型提供了一个详尽的对撞机签名通道列表，并确定了那些在LHC具有非常大的有效截面并且几乎没有标准模型背景的通道。

英文摘要：

We propose a two Higgs doublet Type III seesaw model with $μ$-$τ$ flavor symmetry. We add an additional SU(2) Higgs doublet and three SU(2) fermion triplets in our model. The presence of two Higgs doublets allows for natural explanation of small neutrino masses with triplet fermions in the 100 GeV mass range, without fine tuning of the Yukawa couplings to extremely small values. The triplet fermions couple to the gauge bosons and can be thus produced at the LHC. We study in detail the effective cross-sections for the production and subsequent decays of these heavy exotic fermions. We show for the first time that the $μ$-$τ$ flavor symmetry in the low energy neutrino mass matrix results in mixing matrices for the neutral and charged heavy fermions that are not unity and which carry the flavor symmetry pattern. This flavor structure can be observed in the decays of the heavy fermions at LHC. The large Yukawa couplings in our model result in the decay of the heavy fermions into lighter leptons and Higgs with a decay rate which is about $10^{11}$ times larger than what is expected for the one Higgs Type III seesaw model with 100 GeV triplet fermions. The smallness of neutrino masses constrains the neutral Higgs mixing angle $\sinα$ in our model in such a way that the heavy fermions decay into the lighter neutral CP even Higgs $h^0$, CP odd Higgs $A^0$ and the charged Higgs $H^\pm$, but almost never to the heavier neutral CP even Higgs $H^0$. The small value for $\sinα$ also results in a very long lifetime for $h^0$. This displaced decay vertex should be visible at LHC. We provide an exhaustive list of collider signature channels for our model and identify those that have very large effective cross-sections at LHC and almost no standard model background.

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