Measurement of B meson production fraction ratios in proton-proton collisions at $\sqrt{s}$ = 13 TeV using open-charm and charmonium decays

TL;DR

This paper measures B meson production ratios in proton-proton collisions at 13 TeV using open-charm and charmonium decay channels, providing new insights into B meson production and decay processes with improved precision.

Contribution

It introduces the first absolute normalization of B meson production ratios using combined open-charm and charmonium decay data at 13 TeV.

Findings

Production ratios as functions of pT and y are measured.

First absolute normalization of B meson production ratios.

Isospin invariance in B meson production is confirmed.

Abstract

Production fraction ratios of B$^+$, B$^0$, and B$^0_\mathrm{s}$ 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 allow the use of the open-charm decays of B mesons (B$_\mathrm{(s)}$ $\to$ $\pi$D$_\mathrm{(s)}$) where the D meson decays into fully hadronic final states. Production fraction ratios as functions of B meson transverse momentum ($p_\mathrm{T}$) and rapidity ($y$) are measured using the open-charm decays in the kinematic range of 8 $\lt$ $p_\mathrm{T}$ $\lt$ 60 GeV and $\lvert y \rvert$ $\lt$ 2.25. In addition, the same data are used to measure the relative production fraction ratios with the charmonium decay channels (B$_\mathrm{(s)}$ $\to$ X$\,$J/$\psi$ with X indicating a K$^+$, K$^*$(892)$^0$, or $\phi$(1020) meson) with the J/$\psi$ meson decaying into a pair of muons. By utilizing known branching fractions, precision theoretical calculations, and the open-charm results, the production fraction ratios in the charmonium samples are determined with an absolute normalization for the first time. 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 and observe that it holds within the experimental precision.