The reported CP asymmetry in D->K^+K^- / pi^+pi^- is argued to be too largeto naturally fit the SM. If so, a new source of CP violation is implied in theDelta C=1 sector with a milliweak strength. CP-odd interactions in theflavor-diagonal sector are strongly constrained by the EDMs placing severelimitations on the underlying theory. While the largest effects usually comefrom the New Physics energy scale, they are strongly model-dependent. Yet theinterference of the CP-odd forces manifested in D decays with the conventionalCP-even Delta C=1 weak interaction generates at the charm scale a backgroundlevel. It has been argued that the d_n in the SM is largely generated via suchan interference, with mild KM-specific additional suppression. The reported CPasymmetry is expected to generate d_n of 30 to 100 times larger than in the SM,or even higher in certain model yet not quite natural examples. In the SM thecharm-induced loop-less |d_n| is expected around 10^{-31}e*cm. On the technicalside, we present a compact Ward-identity--based derivation of the inducedscalar pion-nucleon coupling in the presence of the CP-odd interactions, whichappears once the latter include the right-handed light quarks.
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机译：据报道，D-> K ^ + K ^-/ pi ^ + pi ^-中的CP不对称太大，无法自然地适合SM。如果是这样，则在Delta C = 1扇区中隐含了一个强度较弱的新CP违反源。香精-对角线中CP奇数的相互作用受到EDM的强烈限制，从而对基础理论施加了严格的限制。尽管最大的影响通常来自新物理能级，但它们与模型密切相关。然而，D上表现出的CP奇数力的干扰会随着常规CP-偶数Delta C = 1的减弱而减弱，并在魅力级别上产生了背景水平。有人认为，SM中的d_n主要是通过这样的干扰产生的，并带有轻度的KM特有的额外抑制作用。预期所报道的CPasymmetry会产生比SM大30到100倍的d_n，在某些模型中甚至更高，但不是很自然的例子。在SM中，魅惑诱导的无环| d_n |预计约为10 ^ {-31} e * cm。在技术方面，我们提出了一种基于Ward身份的紧凑派生式，该方法基于存在CP-奇数相互作用的情况下诱导标量介子-核子耦合，一旦后者包含右手轻夸克就出现。
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