CMS-PAS-BPH-21-007

CMS-PAS-BPH-21-007
Measurement of $ {\mathrm{B}} $ meson production fractions in proton-proton collisions at $ \sqrt{s} = $ 13 TeV using hadronic open-charm and charmonium decays
CMS Collaboration
25 March 2025

Abstract: Production fractions of B$ ^{\pm} $, B$ ^0 $, and B$ _s^0 $ mesons are measured in proton-proton collisions at $ \sqrt{s} = $ 13 TeV using a special data set recorded in 2018 with high-rate triggers designed to collect an unbiased sample of 10$ ^{10} $ b hadrons with the CMS experiment at the LHC. These data made hadronic open-charm decays of B mesons (B$ _{(s)} \to \pi $D$ _{(s)} $), where the D meson decays into fully hadronic final states, accessible for this measurement. Production fraction ratios as functions of the B meson transverse momentum ($ p_{\mathrm{T}} $) and rapidity ($ y $) are measured using the open-charm decays in the kinematic range of 8 $ < p_{\mathrm{T}} < $ 60 GeV and $ \|y\| < $ 2.25. In addition, the same data are used to measure the relative production fraction ratios in the charmonium decay channels (B$ _{(s)} \to $ X $ \mathrm{J}/\psi $, with X being K, K$ ^{\ast} $(892)$ ^{0} $, $ \phi $(1020) mesons), where the $ \mathrm{J}/\psi $ meson decays into a pair of muons. These measurements are normalized in situ to the measured yields in the open-charm channels, thus allowing, for the first time, the extraction of the production fractions in charmonium channels directly with an absolute normalization. These results also improve several world-average values of the ratios of branching fractions of B meson decays to charmonium and open-charm states. Finally, we test isospin invariance in B meson production in proton-proton collisions.
Links: CDS record (PDF) ; Physics Briefing ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to PRD. The superseded preliminary plots can be found here.

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