Measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math> hadron fractions in 13 TeV <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:mrow></mml:math> collisions

The production fractions of ${\overline{B}}_{s}^{0}$ and ${\mathrm{\ensuremath{\Lambda}}}_{b}^{0}$ hadrons, normalized to the sum of ${B}^{\ensuremath{-}}$ and ${\overline{B}}^{0}$ fractions, are measured in 13 TeV $pp$ collisions using data collected by the LHCb experiment, corresponding to an integrated luminosity of $1.67\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. These ratios, averaged over the $b$ hadron transverse momenta from 4 to 25 GeV and pseudorapidity from 2 to 5, are $0.122\ifmmode\pm\else\textpm\fi{}0.006$ for ${\overline{B}}_{s}^{0}$, and $0.259\ifmmode\pm\else\textpm\fi{}0.018$ for ${\mathrm{\ensuremath{\Lambda}}}_{b}^{0}$, where the uncertainties arise from both statistical and systematic sources. The ${\mathrm{\ensuremath{\Lambda}}}_{b}^{0}$ ratio depends strongly on transverse momentum, while the ${\overline{B}}_{s}^{0}$ ratio shows a mild dependence. Neither ratio shows variations with pseudorapidity. The measurements are made using semileptonic decays to minimize theoretical uncertainties. In addition, the ratio of ${D}^{+}$ to ${D}^{0}$ mesons produced in the sum of ${\overline{B}}^{0}$ and ${B}^{\ensuremath{-}}$ semileptonic decays is determined as $0.359\ifmmode\pm\else\textpm\fi{}0.006\ifmmode\pm\else\textpm\fi{}0.009$, where the uncertainties are statistical and systematic.