• Energy Research
• 2021-2025close

The ratio of the $B^0_s$ and $B^0$ fragmentation fractions, $f_s/f_d$, in proton-proton collisions at the LHC, is obtained as a function of $B$-meson transverse momentum and collision centre-of-mass energy from the combined analysis of different $B$-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum, or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the $B^0_s \to J/����$ and $B^0_s \to D^-_s ��^+$ decays are performed, reducing their uncertainty by about a factor of two with respect to previous world averages. Numerous $B^0_s$ decay branching fractions, measured at the LHCb experiment, are also updated using the new values of $f_s/f_d$ and branching fractions of normalisation channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of $B^0_s$ branching fractions. All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-046.html (LHCb public pages)

AbstractA branching fraction measurement of the $${{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B 0 → D s + π - decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of $$5.0\,\text {fb} ^{-1} $$ 5.0 fb - 1 . The branching fraction is found to be $${\mathcal {B}} ({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} ) =(19.4 \pm $$ B ( B 0 → D s + π - ) = ( 19.4 ± $$1.8\pm 1.3 \pm 1.2)\times 10^{-6}$$ 1.8 ± 1.3 ± 1.2 ) × 10 - 6 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + , $${{D} ^+_{s}} {\rightarrow }{{K} ^+} {{K} ^-} {{\pi } ^+} $$ D s + → K + K - π + and $${{D} ^-} {\rightarrow }{{K} ^+} {{\pi } ^-} {{\pi } ^-} $$ D - → K + π - π - branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a $$b{\rightarrow }u$$ b → u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element $$V_{ub}$$ V ub . Additionally, the collision energy dependence of the hadronisation-fraction ratio $$f_s/f_d$$ f s / f d is measured through $${{\overline{B}} {}^0_{s}} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B ¯ s 0 → D s + π - and $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + decays.

ii, 18 Seiten : Diagramme (2020).