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arXiv 1202.4940hep-ph
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三重规范玻色子顶点中的重费米子非退耦效应

Heavy Fermion Non-Decoupling Effects in Triple Gauge Boson Vertices

Athanasios Dedes, Kristaq Suxho

摘要:

在一个自发破碎的规范组,我们仔细分析和计算三重规范玻色子顶点占主导地位的三角形单圈费曼图涉及重费米子相比,外部动量和规范玻色子质量。我们严格地在四维空间中进行计算,得到了一个离壳单粒子不可约(1 PI)有效顶点的一般公式,它满足相关的沃德恒等式和Goldstone玻色子等价定理.我们的目标是寻找非去耦重费米子效应,突出其与规范手征异常的协同作用。特别是在标准模型中,我们发现当任意反常参数由规范不变性和/或玻色对称性固定时,重费米子的贡献抵消了它的反常贡献,只留下轻费米子的反常贡献和质量无关的贡献。应用这些结果计算了SM模型、最小$Z'$模型及其推广的第四代费米子模型中三重规范玻色子顶点的CP不变单圈诱导修正,并与实验结果进行了比较.

英文摘要:

Within a spontaneously broken gauge group we carefully analyse and calculate triple gauge boson vertices dominated by triangle one-loop Feynman diagrams involving heavy fermions compared to external momenta and gauge boson masses. We perform our calculation strictly in four dimensions and derive a general formula for the off-shell, one-particle irreducible (1PI) effective vertex which satisfies the relevant Ward Identities and the Goldstone boson equivalence theorem. Our goal is to search for non-decoupling heavy fermion effects highlighting their synergy with gauge chiral anomalies. Particularly in the Standard Model, we find that when the arbitrary anomaly parameters are fixed by gauge invariance and/or Bose symmetry, the heavy fermion contribution cancels its anomaly contribution leaving behind anomaly and mass independent contributions from the light fermions. We apply these results in calculating the corresponding CP-invariant one-loop induced corrections to triple gauge boson vertices in the SM, minimal $Z'$models as well as their extensions with a fourth fermion generation, and compare with experimental data.

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