Precision Standard Model: Observables and Inference
Precision Standard Model work is reliable only when the object being inferred is fixed before the statistic is chosen. A complex pole belongs to an amplitude; a pseudo-observable belongs to a stated pole and radiation convention; a fiducial cross section belongs to a measurement function; and a fit belongs to an exact data release, covariance or likelihood, and nuisance model. This chapter builds that chain from definition to combination. It teaches durable methods, not a live summary of measurements or preferred parameter regions.
Enter this chapter
Section titled “Enter this chapter”Begin with Standard Model Pseudo-Observables and Unstable Particles to separate physical amplitude singularities from conventions used to report resonance measurements.
Topics
Section titled “Topics”- Standard Model Pseudo-Observables and Unstable Particles — Defines pole quantities and their relation to unstable particles.
- Electroweak Precision Observables — Organizes electroweak measurements in a consistent input scheme.
- Higgs Precision and Coupling Inference — Relates Higgs category yields to amplitudes and acceptances.
- Collider Measurements, Fiducial Predictions, and Likelihood Provenance — Preserves measurement definitions and released statistical information.
- Correlated Standard Model Fits and Consistency Tests — Combines correlated measurements without counting shared information twice.
How the ideas fit together
Section titled “How the ideas fit together”A measured event yield connects amplitudes to a detector-level selection through efficiencies, migration, and nuisance parameters. A fit must preserve that chain: replacing the released likelihood by independent error bars can discard correlations and duplicate common information. Pole quantities and fiducial cross sections also encode different assumptions, so combining them requires the stated transformation rather than matching their names. An apparently precise result can consequently be less reliable than a wider interval from a complete statistical model. Cranmer et al. 2022, § 2.
Where to go next
Section titled “Where to go next”Continue to Consistent Extensions and Portals to test a proposed extension’s fields, symmetries, and mass generation.