在破壞“電荷共軛（C）與時間反轉（T）對稱性”的新物理領域，η→π+π-γ輻射衰變可以視為研究的引子。我們研究此輻射衰變的CP破壞性質，並敘述有助於觀察該性質的量測方法。我們證明：經由考慮光子的線性與圓偏極性，η→π+π-γ衰變可以違反CP的對稱性。在標準模型的架構下，光子偏極性的比率很小。然而，在不考慮模型的假設，單就Br（η→π+π-）的實驗限制而言，該偏極率允許上至O（10％）。另外，我們也探究各種可能的算符。我們發現：自S夸克的電偶極子（CP破壞）合理衍生出的張量算符，可以導致相當大的光子線性偏極。

The radiative decay η→ππγ can be a probe of new physics that violates charge conjugation (C) and time reversal (T) symmetries. We discuss the measurements required to facilitate such observations. We study the CP violating effects in the decay. We show that to have CP violation in the decay, one has to consider both linear and circular photon polarizations. In the standard model, the polarizations are vanishingly small. However, model-independently, i.e. using only experimental constraint imposed by the limit on Br(η→π+π-) it can be up to O(10%). We also explore various possible operators and we find that the tensor type operator, possibly arising from a nonzero CP violating electric dipole moment of the strange quark, can induce a sizable linear photon polarization.

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