标准模型以及超越 第2版

　　Much has （or has not） happened in the seven years or so since the publication of the first edition of this book. Most notably， a new spin-0 particle with mass~125 GeV was discovered at the LHC by the ATLAS and CMS collaborations， which is either the elementary Higgs boson or something that closely resembles it. The Higgs discovery completes the ≥40 year saga of verifying the standard model （SM）. Moreover， its mass is almost maximally interesting： it is near the top of the range predicted by the most popular SM extension，minimal supersymmetry， and near the minimum value consistent with the unextended SM （and then only if the vacuum is metastable）！However， the notorious problems of the SM are still unresolved. Perhaps the most press-ing is the apparently fine-tuned hierarchy between the weak interaction and gravity scales.Extensive searches at the LHC and elsewhere have so far not yielded any compelling evidence for new TeV-scale physics such as supersymmetry， extra space dimensions， or strong cou-pling that had been proposed to explain or at least stabilize the hierarchy. Equally puzzling is the nature of the dark energy and its incredibly tiny magnitude compared to most theo-retical expectations. Similarly， numerous experimental attempts to identify the mysterious dark matter inferred from its gravitational effects have not as yet had any positive results and have excluded much of the parameter space for supersymmetric dark matter. And de-spite the great experimental success of the SM， it is a very complicated theory， involving severalinteractions with different properties， and two apparently superfl.uous heavier copies of the fundamental particles that constitute ordinary matter under ordinary conditions. For these and other reasons， many theorists have started exploring less canonical possibilities，such as a dark matter sector that is at most very weakly coupled to ordinary particles，or， more radically， that the Universe is part of a vast multiverse of regions （presumably associated with a superstring landscape of vacua with different laws of physics.

　　保罗·兰盖克 （Paul Langacker），美国物理学家，宾夕法尼亚大学物理与天文系荣休教授，并曾担任系主任，他还是普林斯顿高等研究院的长期客座研究员。他的研究强调基础理论和实验之间的联系，包括精密电弱物理、大统一理论、中微子物理、Z'物理和弦唯象学等。他是美国物理学会（APS）和美国科学促进会（AAAS）的杰出会士。