Heidelberg 2022 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 3: Flavour Physics 1
T 3.7: Vortrag
Montag, 21. März 2022, 17:45–18:00, T-H16
From sWeights to COWs: News about the sWeight method — •Hans Dembinski1, Matt Kenzie2, Christoph Langenbruch3, and Michael Schmelling4 — 1TU Dortmund, Germany — 2University of Warwick, United Kingdom — 3RWTH Aachen, Germany — 4MPIK Heidelberg
A common problem in experimental flavour physics is the separation of signal and background, when the background is difficult to parameterise. We revisit the foundation of the popular method known as sWeights (or sPlot), which allows one to calculate estimates from the signal density in a control variable (for example, the decay time of a particle) using a fit of a mixed signal and background model to a discriminating variable (typically the invariant mass of decay candidates). sWeights are a special case of a larger class of Custom Orthogonal Weight functions (COWs), which can be applied to a more general class of problems in which the discriminating and control variables are not necessarily independent and still achieve close to optimal performance. We present new insights into the properties of parameters estimated from fits to sWeighted data, and provide closed formulas for the asymptotic covariance matrix of these parameters. To illustrate our findings, we show practical applications of these techniques.