Journeys Through the Precision Frontier: Amplitudes for Colliders

The following sections are included:

• Preface
• TASI 2014 Group Photo: Identification List
• Contents

These lectures introduce the basic concepts of quantum chromodynamics (QCD), the theory of the strong interaction, and discuss applications of QCD to particle physics observables at high energy colliders.

I provide a basic introduction to modern helicity amplitude methods, including color organization, the spinor helicity formalism, and factorization properties. I also describe the BCFW (on-shell) recursion relation at tree level, and explain how similar ideas — unitarity and on-shell methods — work at the loop level. These notes are based on lectures delivered at the 2012 CERN Summer School and at TASI 2013, and are close to the material Zvi Bern lectured on at TASI 2014.

The lectures presented below cover the basics of proton-proton collisions at the LHC, the principles of particle detection, the methodologies employed for reconstruction of individual collision events, general strategies for signal event selection, data-driven techniques for evaluating signal efficiencies and background rates, as well as the main statistical concepts used for physics inference from selected data. The described principles and concepts are then illustrated on an example of a search for a Higgs boson and measurement of its properties in the H → ZZ → 4ℓ decay mode. The discussion is largely based on CMS, taken as a representative LHC experiment.

Nonperturbative QCD effects are ubiquitous and affect not just processes studied in particle and nuclear physics, but also in astrophysics and cosmology. Lattice field theory is a general quantitative tool for the study of nonperturbative phenomena and has provided us with much insight into nonperturbative QCD effects. In these lectures I present an introduction to lattice QCD with emphasis on the methods used for calculations relevant to quark flavor physics. In lattice QCD, quantitative control over systematic errors is made possible with the use of effective field theories. I briefly review how the effective field theories arise and their relation to the sources of systematic error in lattice QCD.

This lecture discusses the physics implemented by Monte Carlo event generators for hadron colliders. It details the construction of parton showers and the matching of parton showers to fixed-order calculations at higher orders in perturbative QCD. It also discusses approaches to merge calculations for a varying number of jets, the interface to the underlying event and hadronization.

These notes overlap with lectures given at the TASI summer schools in 2014 and 2011, as well as at the European School of High Energy Physics in 2013. This is primarily an attempt at transcribing my handwritten notes, with emphasis on topics and ideas discussed in the lectures. It is not a comprehensive introduction or review of the field, nor does it include a complete list of references. I hope, however, that some may find it useful to better understand the reasons for excitement about recent progress and future opportunities in flavor physics.

These lecture notes provide a lightning introduction to some aspects of scattering amplitudes in maximally supersymmetric theory, aimed at the audience of students attending the 2014 TASI summer school “Journeys Through the Precision Frontier: Amplitudes for Colliders”. Emphasis is placed on explaining modern terminology so that students needing to delve further may more easily access the available literature.

These lecture notes briefly review holography, or gauge/gravity duality. They also discuss its application to computing the viscosity of a strongly-coupled fluid, and to describing charge transport in the holographic superconductor.

These lectures introduce the modern machinery used in searches and studies of new physics Beyond the Standard Model (BSM) at colliders. The first lecture provides an overview of the main simulation tools used in high energy physics, including automated parton-level calculators, general purpose event generators, detector simulators, etc. The second lecture is a brief introduction to low energy supersymmetry (SUSY) as a representative BSM paradigm. The third lecture discusses the main collider signatures of SUSY and methods for measuring the masses of new particles in events with missing energy.

In these lectures we discuss some of the mathematical structures that appear when computing multi-loop Feynman integrals. We focus on a specific class of special functions, the so-called multiple polylogarithms, and introduce their Hopf algebra structure. We show how these mathematical concepts are useful in physics by illustrating on several examples how these algebraic structures are useful to perform analytic computations of loop integrals, in particular to derive functional equations among polylogarithms.

In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action, these structures are currently only understood in terms of graphical organizational principles, such as the gauge-theoretic color-kinematics duality and the gravitational double-copy structure, for local representations of multi-loop S-matrix elements. These graphical principles make manifest new relationships in and between gauge and gravity scattering amplitudes. My lectures will focus on arriving at such graphical organizations for generic theories with examples presented from maximal supersymmetry, and their use in unitarity-based multiloop integrand construction.

These lectures, given at the 2014 Theoretical Advanced Study Institute (TASI), are an introduction to what we know at present about dark matter and the major current experimental and observational efforts to identify what it consists of. They attempt to present the complexities of the subject, making clear common simplifying assumptions, to better understand the reach of dark matter searches.

The following sections are included:

• Chapter 13: TASI 2014 Participants