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arXiv 0712.4345hep-ph
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介质中的洛伦兹对称性破坏衰变

Lorentz-symmetry violating decays in a medium

José F. Nieves, Palash B. Pal

摘要:

各种衰变过程,例如自旋为1的粒子衰变为两个光子或自旋为1/2的费米子的引力衰变,在真空中被角动量守恒、洛伦兹不变性和规范不变性等要求的组合所禁止。我们表明,这样的过程可以发生在介质中,如粒子的热背景,即使它是均匀的和各向同性的。我们进行了一个模型无关的分析,这样的过程中的一组形状因子的顶点函数,并表明,振幅可以是非零的,同时保持与上述对称性原则。结果模拟洛伦兹对称性破坏效应,虽然在这种情况下,它们产生于完全洛伦兹不变的物理。

英文摘要:

Various decay processes, such as the decay of a spin-1 particle into two photons or the gravitational decay of a spin-1/2 fermion, are forbidden in the vacuum by a combination of requirements, including angular momentum conservation, Lorentz invariance and gauge invariance. We show that such processes can occur in a medium, such as a thermal background of particles, even if it is homogeneous and isotropic. We carry out a model-independent analysis of the vertex function for such processes in terms of a set of form factors, and show that the amplitude can be non-zero while remaining consistent with the symmetry principles mentioned above. The results simulate Lorentz symmetry violating effects, although in this case they arise from completely Lorentz-invariant physics.

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