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arXiv 1609.03561hep-phhep-ex
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含细夸克的扩展标准模型的真空稳定性

Vacuum stability in an extended standard model with a leptoquark

Priyotosh Bandyopadhyay, Rusa Mandal

摘要:

我们研究了具有$-1/3$单位分数电磁荷的带电标量扩展以及轻子和重子数违反树级耦合的标准模型。在不直接参与电弱(EW)对称性破缺的情况下,该标量可以通过回路效应影响EW真空的稳定性。这种标量的影响,即,本文在双圈量级上研究了一个轻子夸克对SM无量纲耦合微扰性以及对新物理耦合微扰性的影响。用单圈重整化群(RG)改进的有效势方法和双圈β函数检验了Higgs势的真空稳定性。从稳定性分析的各种界限上绘制的参数空间,通过识别对应的区域的EW真空的亚稳性和稳定性。后来,我们还通过Veltman条件解决希格斯质量微调问题,这种标量的存在增加了理论可以被认为是合理微调的规模。所有这些约束条件给出了一个非常有预测性的参数空间的leptoquark耦合,可以测试在目前和未来的对撞机。特别是,质量为$\mathcal{O}\,$(TeV)的轻子夸克通过衰变进入树水平的$t\, τ$通道,可以产生轻子-夸克味违反特征,这可以在LHC或未来的对撞机上进行测试。

英文摘要:

We investigate the standard model (SM) with the extension of a charged scalar having fractional electromagnetic charge of $-1/3$ unit and with lepton and baryon number violating couplings at tree level. Without directly taking part in the electro-weak (EW) symmetry breaking, this scalar can affect stability of the EW vacuum via loop effects. The impact of such a scalar, i.e., a leptoquark on the perturbativity of SM dimensionless couplings as well as on new physics couplings has been studied at two-loop order. The vacuum stability of the Higgs potential is checked using one-loop renormalization group (RG) improved effective potential approach with two-loop beta function for all the couplings. From the stability analysis various bounds are drawn on parameter space by identifying the region corresponding to metastability and stability of the EW vacuum. Later we also address the Higgs mass fine-tuning issue via Veltman condition and the presence of such scalar increases the scale up to which the theory can be considered as reasonably fine-tuned. All these constraints give a very predictive parameter space for leptoquark couplings which can be tested at present and future colliders. Especially, a leptoquark with mass $\mathcal{O}\,$(TeV) can give rise to lepton-quark flavor violating signatures via decaying into the $t\, τ$ channel at tree level, which can be tested at the LHC or future colliders.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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