Improving $b$-Tagging Precision in Proton-Proton Collisions at the LHC

The ATLAS Collaboration has published a paper detailing the calibration of a soft secondary vertex tagger, which is crucial for identifying $b$-flavored hadrons in proton-proton collisions at the Large Hadron Collider (LHC). This calibration is based on a dataset from collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 140 fb^-1.

The tagging algorithm focuses on reconstructing soft secondary vertices that originate from the decays of $b$-flavored hadrons, which are often produced in processes studied by the ATLAS experiment. The authors extracted scale factors to correct the algorithm's performance in simulated events, specifically targeting the $b$-tagging efficiency and the mistag rate using a sample enriched in top quark pair ($t\bar{t}$) events.

To enhance the accuracy of their measurements, the authors defined several orthogonal measurement regions, which were binned based on the multiplicities of soft secondary vertices and jets containing $b$-flavored hadrons. They estimated mistag rate scale factors separately for events with low and high average numbers of interactions per bunch crossing. The results derived from events with low missing transverse momentum were validated in a phase space characterized by high missing transverse momentum, indicating their applicability to searches for new physics across different regimes.

This calibration work is significant as it improves the precision of $b$-tagging in high-energy physics experiments, which is essential for various analyses, including those searching for new particles and phenomena beyond the Standard Model. The findings can enhance the understanding of fundamental processes in particle physics and contribute to the ongoing research at the LHC.

The paper, titled "Calibration of a soft secondary vertex tagger using proton-proton collisions at $\sqrt{s}=$13 TeV with the ATLAS detector," can be accessed through arXiv with the identifier arXiv:2405.03253.