No abstract

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,324 new measurements from 878 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on High Energy Soft QCD and Diffraction and one on the Determination of CKM Angles from B Hadrons. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 98 review articles. Volume 2 consists of the Particle Listings and contains also 22 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print and as a web version optimized for use on phones as well as an Android app.

We present a phase-plane analysis of cosmologies containing a baryotropic fluid with an equation of state p ␥ ϭ(␥Ϫ1) ␥ , plus a scalar field with an exponential potential Vϰexp(Ϫ) where 2 ϭ8G. In addition to the well-known inflationary solutions for 2 Ͻ2, there exist scaling solutions when 2 Ͼ3␥ in which the scalar field energy density tracks that of the baryotropic fluid ͑which for example might be radiation or dust͒. We show that the scaling solutions are the unique late-time attractors whenever they exist. The fluid-dominated solutions, where V()/ ␥ →0 at late times, are always unstable ͑except for the cosmological constant case ␥ϭ0). The relative energy density of the fluid and scalar field depends on the steepness of the exponential potential, which is constrained by nucleosynthesis to 2 Ͼ20. We show that standard inflation models are unable to solve this ''relic density'' problem. ͓S0556-2821͑98͒05408-3͔ PACS number͑s͒: 98.80.Cq

We present a detailed investigation of chaotic ination models which feature two scalar elds, such that one eld (the inaton) rolls while the other is trapped in a false vacuum state. The false vacuum becomes unstable when the magnitude of the inaton eld falls below some critical value, and a rst or second order transition to the true vacuum ensues. Particular attention is paid to the case, termed`Hybrid Ination' by Linde, where the false vacuum energy density dominates, so that the phase transition signals the end of ination. We focus mostly on the case of a second order transition, but treat also the rst order case and discuss bubble production in that context for the rst time.False vacuum dominated ination is dramatically dierent from the usual true vacuum case, both in its cosmology and in its relation to particle physics. The spectral index of the adiabatic density perturbation originating during ination can be indistinguishable from 1, or it can be up to ten percent or so higher. The energy scale at the end of ination can be anywhere between 10 16 GeV, which is familiar from the true vacuum case, and 10 11 GeV. On the other hand reheating is prompt, so the reheat temperature cannot be far below 1 0 11 GeV. Cosmic strings or other topological defects are almost inevitably produced at the end of ination, and if the inationary energy scale is near its upper limit they contribute signicantly to large scale structure formation and the cosmic microwave background anisotropy.Turning to the particle physics, false vacuum ination occurs with the inaton eld far below the Planck scale and is therefore somewhat easier to implement in the context of supergravity than true vacuum chaotic ination. The smallness of the inaton mass compared with the inationary Hubble parameter still presents a diculty for generic supergravity theories. Remarkably however, the diculty can be avoided in a natural way for a class of supergravity models that follow from orbifold compactication of superstrings. This opens up the prospect of a truly realistic, superstring derived theory of ination. One possibility, which w e show t o be viable at least in the context of global supersymmetry, is that the Peccei-Quinn symmetry is responsible for the false vacuum.

We review the theory of inflation with single and multiple fields paying particular attention to the dynamics of adiabatic and entropy/isocurvature perturbations which provide the primary means of testing inflationary models. We review the theory and phenomenology of reheating and preheating after inflation providing a unified discussion of both the gravitational and nongravitational features of multi-field inflation. In addition we cover inflation in theories with extra dimensions and models such as the curvaton scenario and modulated reheating which provide alternative ways of generating large-scale density perturbations. Finally we discuss the interesting observational implications that can result from adiabatic-isocurvature correlations and non-Gaussianity.