Electroweak instantons are a prediction of the Standard Model and have been studied in great detail in the past although they have not been observed. Earlier calculations of the instanton production cross-section at colliders revealed that it was exponentially suppressed at low energies, but may grow large at energies (much) above the sphaleron mass. Such calculations faced difficulty in the breakdown of the instanton perturbation theory in the high-energy regime. In this paper, we review the calculation for the electroweak instanton cross-section using the optical theorem, including quantum effects arising from interactions in the initial state and show that this leads to an exponential suppression of the cross-section at all energies, rendering the process unobservable.

中文翻译：

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高能碰撞中电弱瞬时过程的抑制

电弱瞬时子是标准模型的一种预测，过去已经对其进行了非常详细的研究，尽管它们尚未被观察到。早先对对撞机的瞬子产生横截面的计算表明，它在低能量时呈指数抑制，但在能量（远）高于回旋体质量时可能会变大。这样的计算在打破高能状态下的瞬时微扰理论时遇到了困难。在本文中，我们回顾了使用光学定理对电弱瞬时子截面的计算，包括初始状态下相互作用产生的量子效应，并表明这会导致截面在所有能量下的指数抑制，从而使过程不可观察。