Perimeter Institute for Theoretical Physics, 31 Caroline Street N, Waterloo, Ontario, Canada N2L 2Y5.
Perimeter Institute for Theoretical Physics, 31 Caroline Street N, Waterloo, Ontario, Canada N2L 2Y5 and Department of Physics & Astronomy, University of Victoria, Victoria, British Columbia, Canada V8P 5C2.
Phys Rev Lett. 2014 Aug 29;113(9):091801. doi: 10.1103/PhysRevLett.113.091801. Epub 2014 Aug 28.
The production of a μ+ μ- pair from the scattering of a muon neutrino off the Coulomb field of a nucleus, known as neutrino trident production, is a subweak process that has been observed in only a couple of experiments. As such, we show that it constitutes an exquisitely sensitive probe in the search for new neutral currents among leptons, putting the strongest constraints on well-motivated and well-hidden extensions of the standard model gauge group, including the one coupled to the difference of the lepton number between the muon and tau flavor, Lμ-Lτ. The new gauge boson Z', increases the rate of neutrino trident production by inducing additional (μγαμ)(νγ(α)ν) interactions, which interfere constructively with the standard model contribution. Existing experimental results put significant restrictions on the parameter space of any model coupled to muon number Lμ, and disfavor a putative resolution to the muon g-2 discrepancy via the loop of Z' for any mass mZ'≳400 MeV. The reach to the models' parameter space can be widened with future searches of the trident production at high-intensity neutrino facilities such as the LBNE.
从μ子中微子散射原子核的库仑场中产生μ+μ-对，称为中微子三叉戟产生，是一种亚弱过程，仅在几个实验中观察到。因此，我们表明它是在寻找轻子之间新的中性电流的极其敏感的探针，对标准模型规范群的合理和隐藏的扩展，包括与μ子和τ子味之间的轻子数差耦合的扩展，施加了最强的限制Lμ-Lτ。新的规范玻色子 Z'通过诱导额外的(μγαμ)(νγ(α)ν)相互作用来增加中微子三叉戟产生的速率，这些相互作用与标准模型的贡献相建设性地干涉。现有的实验结果对任何与μ子数 Lμ耦合的模型的参数空间施加了重要限制，并反对通过 Z'的循环来解决μ子 g-2 差异，对于任何质量 mZ'≳400 MeV。通过未来在 LBNE 等高强度中微子设施中对三叉戟产生的搜索，可以扩大对模型参数空间的探测范围。
