CERN Theory Division, CH-1211 Geneva 23, Switzerland and Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, CH-3012 Bern, Switzerland.
Department of Physics, University of California, Berkeley, California 94720, USA and Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Phys Rev Lett. 2014 May 16;112(19):191304. doi: 10.1103/PhysRevLett.112.191304.
We consider an effective field theory for a gauge singlet Dirac dark matter particle interacting with the standard model fields via effective operators suppressed by the scale Λ ≳ 1 TeV. We perform a systematic analysis of the leading loop contributions to spin-independent Dirac dark matter-nucleon scattering using renormalization group evolution between Λ and the low-energy scale probed by direct detection experiments. We find that electroweak interactions induce operator mixings such that operators that are naively velocity suppressed and spin dependent can actually contribute to spin-independent scattering. This allows us to put novel constraints on Wilson coefficients that were so far poorly bounded by direct detection. Constraints from current searches are already significantly stronger than LHC bounds, and will improve in the near future. Interestingly, the loop contribution we find is isospin violating even if the underlying theory is isospin conserving.
我们考虑了一种有效场理论，其中一个规范单态狄拉克暗物质粒子通过有效算子与标准模型场相互作用，这些算子受到尺度 Λ ≳ 1 TeV 的抑制。我们使用重整化群演化方法，在 Λ 和直接探测实验探测到的低能标之间，对自旋无关的狄拉克暗物质-核子散射的主要环贡献进行了系统分析。我们发现，电弱相互作用会引起算子混合，使得原本被速度抑制且自旋相关的算子实际上可以对自旋无关散射做出贡献。这使得我们能够对威尔逊系数施加新的约束，这些系数之前由于直接探测的限制而被很好地束缚住了。目前的搜索结果已经比 LHC 的限制强了很多，并且在不久的将来还会进一步提高。有趣的是，即使基础理论是同位旋守恒的，我们发现的环贡献也是同位旋破坏的。
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