Measurement of $b$-quark fragmentation properties in jets using the decay $B^{\pm} \to J/\psi K^{\pm}$ in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The collaboration
CERN-EP-2021-123, 2021.

Abstract (data abstract)
CERN-LHC. The fragmentation properties of $b$-quark initiated jets are studied using charged $B$ mesons in 139 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. $B$ mesons are reconstructed using the decay of $B^{\pm}$ to $J/\psi K^{\pm}$, with the $J/\psi$ decaying into a pair of muons. Jets are reconstructed using the anti-$k_t$ algorithm with radius $R=0.4$. The measurement consists on the determination of the longitudinal and transverse momentum profiles of the reconstructed $B$ hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to 100 GeV. The results are corrected for detector effects and compared to several Monte Carlo predictions with different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy flavour fragmentation in jets.