000000974 001__ 974
000000974 005__ 20180629113639.0
000000974 037__ $$aBELLE2-TALK-CONF-2018-072
000000974 041__ $$aeng
000000974 088__ $$aBELLE2-TALK-DRAFT-2018-075
000000974 100__ $$aFernando Abudinén.
000000974 245__ $$aThe Belle II flavor tagger
000000974 260__ $$aCHEP 2018$$c2018-07-11
000000974 300__ $$a12
000000974 500__ $$a12+3 min
000000974 520__ $$aMeasurements of time-dependent CP violation and of B-meson mixing at B-factories require a determination of the flavor of one of the two exclusively produced B0 mesons. The predecessors of Belle II, the Belle and BaBar experiments, developed so-called flavor tagging algorithms for this task. However, due to the novel high-luminosity conditions and the increased beam-backgrounds at Belle II, a new flavor tagging algorithm had to be developed with a specific and dedicated optimization in order to be applied in precision measurements while coping with the harsher experimental conditions. The new Belle II flavor tagging algorithm, the so-called Belle II flavor tagger, bases on inclusive methods that exploit the flavor specific signatures of B0 decays, considering more signatures than in the previous algorithms and employing novel multivariate approaches. It proceeds in two steps: the event level, where candidate particles providing flavor specific signatures are selected; and the combiner, where all the possible signatures are combined into the final output. The framework is now complete and ready for use in data analysis, reaching an effective tagging efficiency of ca. 37% on Belle II Monte Carlo (MC). A major test consists in applying the Belle II flavor tagger algorithm in analysis with Belle data. For this, the Belle II flavor tagger was trained with Belle MC and tested with Belle data reaching an effective efficiency of 34% (Belle reached 30%). Additionally, the shape of the Belle II flavor tagger output shows good agreement between Belle data and Belle MC, meeting also the requirements to be used for analysis of Belle data.
000000974 6531_ $$aFlavor tagger
000000974 8560_ $$ffernando.jesus.abudinen@desy.de
000000974 8564_ $$uhttps://docs.belle2.org/record/974/files/BELLE2-TALK-CONF-2018-072.pdf