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arXiv 0904.2528hep-ph
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从K -> pi nu anti-nu和K_K的相互作用对新物理风味结构的启示

Insights from the Interplay of K -> pi nu anti-nu and epsilon_K on the New Physics Flavour Structure

Monika Blanke

摘要:

在某些新的物理模型中,如T宇称的Littlest Higgs模型,K_L -> pi 0 nu anti-nu和K+ -> pi+ nu anti-nu分支比之间存在严格的相关性,基本上只允许两个分支的可能点,而在其他的NP框架中,如一般的MSSM或扭曲的额外维模型,没有明显的相关性出现。我们分析了相关性的起源问题,并表明它是一个直接的后果,严格的实验约束的NP_K,提供了NP进入具有可比的强度和一个普遍的弱相在两个Δ S = 2和Δ S = 1的转变。这发生在许多NP场景中,只有SM算子,或者NP只感应右手电流,而没有左右Delta S = 2算子。另一方面,如果Delta S = 2和Delta S = 1过程中的NP阶段是不相关的,则Kk_K没有能力对K -> pi nu anti-nu系统施加约束。后者特别出现在那些NP模型中,其中K^0 -反K^0混合得到手征增强的左右算子的贡献。我们讨论了稳定性的相关问题对小偏差的假设普遍Δ S = 2和Δ S = 1弱相位,并在存在不可忽略的NP贡献的情况下,对K_K。

英文摘要:

In certain new physics (NP) models, such as the Littlest Higgs model with T-parity, a strict correlation between the K_L -> pi0 nu anti-nu and K+ -> pi+ nu anti-nu branching ratios has been observed, allowing essentially only for two branches of possible points, while in other NP frameworks, such as the general MSSM or warped extra dimensional models, no visible correlation appears. We analyse the origin of the correlation in question and show it to be a direct consequence of the stringent experimental constraint on epsilon_K, provided that the NP enters with comparable strength and a universal weak phase in both Delta S = 2 and Delta S = 1 transitions. This happens in many NP scenarios with either only SM operators, or where the NP induces exclusively right-handed currents while the left-right Delta S = 2 operators are absent. On the other hand, if the NP phases in Delta S = 2 and Delta S = 1 processes are uncorrelated, epsilon_K has no power to put constraints on the K -> pi nu anti-nu system. The latter appears in particular in those NP models where K^0 - anti-K^0 mixing receives contributions from the chirally enhanced left-right operators. We discuss the stability of the correlation in question against small deviations from the assumption of universal Delta S = 2 and Delta S = 1 weak phases, and in the presence of non-negligible NP contributions to epsilon_K.

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