Accuracy and Precision in Collider Event Shapes

Abstract

In this thesis, we discuss and investigate the use of Soft-Collinear Effective Theory (SCET) for high precision calculations. In the first part of the work, we present an extraction of the strong coupling, ${\alpha }_s(m_Z)$ and the leading nonperturbative parameter ${\Omega }_1$, using the event shape C-parameter. By comparing lepton collider data to the C-parameter cross section, we extract values ${\alpha }_s(m_Z)=0.1123\pm 0.0015$ and ${\Omega }_1=0.421\pm 0.063\mathrm{GeV}$ with ${\chi }^2/\mathrm{dof}=0.988$ for $404$ bins of data. The later parts of this thesis are dedicated to using on-shell helicity methods to extend SCET beyond leading power. We present a complete set of scalar helicity building blocks and describe an interesting angular momentum selection rule that restricts how these building blocks can be assembled.

Ph.D. thesis, MIT, May 2016, 167 pages, 42 figures

References in corpus (19)

• Thrust at N^3LL with Power Corrections and a Precision Global Fit for alphas(mZ)
• Quark and gluon form factors to three loops
• Treating the b quark distribution function with reliable uncertainties
• Second-order QCD corrections to the thrust distribution
• High-precision quark masses and QCD coupling from $n_f=4$ lattice QCD
• Factorization of e+e- Event Shape Distributions with Hadronic Final States in Soft Collinear Effective Theory
• Resummation of heavy jet mass and comparison to LEP data
• Designing Gapped Soft Functions for Jet Production
• C-parameter Distribution at N${}^3$LL${}^{\prime }$ including Power Corrections
• The strong coupling from the revised ALEPH data for hadronic $\tau$ decays
• A Precise Determination of ${\alpha }_s$ from the C-parameter Distribution
• NNLO moments of event shapes in e+e- annihilation
• Non-Perturbative Contribution to the Thrust Distribution in $e^{+}{e}^{-}$ Annihilation
• Building Blocks for Subleading Helicity Operators
• Reparameterization Invariant Collinear Operators
• Dissecting Soft Radiation with Factorization
• Hemisphere Soft Function at O(alpha_s^2) for Dijet Production in e+e- Annihilation
• Automated Calculation of Dijet Soft Functions in Soft-Collinear Effective Theory
• Effective Field Theories for the LHC