Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 65: Experimental methods III

T 65.7: Talk

Wednesday, March 17, 2021, 17:30–17:45, To

Impact Parameter Resolution Studies in the ATLAS detector — •Supriya Sinha — DESY, Zeuthen

For many physics studies in ATLAS, b-quark identification emerges to be a very crucial component of the analysis. This is particularly useful in studies involving the selection of pure top quark samples, search for new physics, studying the Standard Model, etc.

The Impact Parameter (IP) is defined as the distance of closest approach of a track to the Primary Vertex (PV). It is the key-ingredient for discriminating the tracks originating from the PV, from the ones originating from displaced vertices, e.g. from decays of b-hadrons. Precise measurement of the IP of charged particle tracks and correct modelling in simulation is fundamental for b-tagging performance.

The resolution of the IP is effected by many factors: intrinsic single hit resolution, multiple scattering inside the detector material, etc. These are difficult to simulate and hence, the track IP reconstruction performance in Monte Carlo (MC) may need additional tuning to reproduce the data precisely. However, the track IP resolution is contaminated by the PV resolution, which has to be eliminated to get the intrinsic (unfolded) IP resolution of the track. This talk shows the comparison of IP resolution for data and MC for different years. In addition, the comparison is done for different track qualities defined for the b-tagging purposes.