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T: Fachverband Teilchenphysik
T 26: Methods in Particle Physics II
T 26.2: Vortrag
Dienstag, 17. März 2026, 16:30–16:45, KH 00.020
Precision Luminosity Measurement with Standard Candles using HLT Scouting Data — •Tatiana Selezneva — Karlsruher Institut für Technologie, Karlsruhe, Deutschland
Precise determination of instantaneous and integrated luminosity at the LHC becomes increasingly challenging as collision rates rise and radiation damage accumulates in the CMS detector. Alongside the baseline luminosity determination, Standard Candle processes offer valuable complementary constraints. Although an absolute calibration below the 1% level is limited by theoretical cross-section uncertainties, such measurements are essential for validating long-term stability and linearity.
CMS has extensive experience with Z counting, benefiting from the clean Z→µµ signature and efficient high-pT muon reconstruction. A complementary approach is based on J/ψ production, which features a much larger cross section and thus higher event rates, including during van der Meer scans. By recording most reconstructed muons in a reduced data format, the HLT Scouting stream enables rates up to 30 kHz without degrading reconstruction performance, compensating for the suppression of low-pT muons by standard triggers.
While the statistical gain for Z counting is moderate, the rapid availability of Scouting data enables near real-time luminosity monitoring using both Z and J/ψ. In addition, first results on W counting are presented, providing an orthogonal observable that can further constrain Z-based luminosity through its dependence on the electroweak mixing angle.
Keywords: CMS; Luminosity; Scouting; Muons