有效场论和精确电弱分析在LHC上的新物理研究

The CMS and ATLAS collaboration at the CERN Large Hadron Collider (LHC) both reported the discovery of a SM-like Higgs boson with 125 GeV, which inspires physical society of the whole world. This result is not only a success of the standard model, but also gives rise to new challenges to theoretists and experimentalists. It involves whether the scalar with 125 GeV is concretely the SM-like one, and where the new physics is (Due to the flaws in the standard model, there must exsit such an UV completion) ? This proposal is devoted to study the origin of electroweak symmetry breaking in light of the LHC data including the discovery of 125 GeV Higgs, diphoton, four-lepton, two tau, bb decay channels and others involved. In particular, we will study the implications to supersymmetric standard model and new physics composed of few new parameters, in terms of the effective field theory and electroweak precise tests. The parameter space of these two representative models can be analyzed when confronting them with the experimental data. The outcomes of this proposal will guide us to identify the mechanism of electroweak symmetry breaking and confirm or exclude these two types of new physics.

LHC的CMS和ATLAS 合作组同时观测到125 GeV 的Higgs， 这个发现震撼了粒子物理学界。这既是电弱破缺模型的成功，同时对理论家和实验家提出了新的，更严峻的挑战。 125GeV 玻色子是否是标准模型的Higgs，超越标准模型的新物理（由于标准模型存在缺陷，我们知道它一定存在）又在哪? 在我们计划进行的研究中，我们对LHC观测到的双光子，四轻子末态等过程进行深入研究。通过拟合实验数据，可以对标准模型理论进行精确检验，以求得到对电弱理论深层次的认识。我们开展对超对称以及其他具有较少参数的超越标准模型的新物理模型的研究, 利用有效场论等理论工具计算可以由实验检验的物理量，做出模型相关的理论预言, 判定超对称或其他模型的合理性，并限定这些模型的参数空间。

依据项目计划, 我们对精确测量有关的物理参数进行了系统的解析计算。结合大型强子对撞机上的最新实验数据, 我们利用已获得的理论结果检验了最小超对称(MSSM)和次最小超对称(NMSSM)。结果表明125 GeV的希格斯粒子质量和超对称粒子质量的下限已经对MSSM提出了很强的限制, 而与NMSSM能较好的吻合。最后, 我们在新模型构造方面进行了一些尝试。我们提出基于gauge mediation的超对称模型可以解释125 GeV希格斯质量;我们还获得了满足Higgs inflation条件下有关超对称粒⼦质量新的限制。