cern.ch

Differential branching fraction and angular analysis of the $B^+ \to K^+ \mu^+ \mu^-$ decay

[to restricted-access page]

Abstract

The angular distribution and differential branching fraction of the decay $B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}$ are studied with a dataset corresponding to $1.0\,\mathrm{fb}^{-1}$ of integrated luminosity, collected by the LHCb experiment. The angular distribution is measured in bins of dimuon invariant mass squared and found to be consistent with Standard Model expectations. Integrating the differential branching fraction over the full dimuon invariant mass range yields a total branching fraction of $\mathcal{B}(B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}) = (4.36 \pm 0.15 \pm 0.18)\times 10^{-7}$. These measurements are the most precise to date of the $B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}$ decay.

Figures and captions

Invariant mass of selected $ B ^+ \!\rightarrow K ^+ \mu ^+\mu ^- $ candidates with $0.05 < q^{2} < 22.00\mathrm{\,GeV} ^{2}/c^{4}$. Candidates with a dimuon invariant mass consistent with that of the $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ or $\psi {(2S)}$ are excluded. The peaking background contribution from the decays $ B ^+ \!\rightarrow K ^+ \pi ^+ \pi ^- $ and $ B ^+ \!\rightarrow \pi ^+ \mu ^+\mu ^- $ is indicated in the figure.

mass_Kmumu.pdf [33 KiB]
HiDef png [190 KiB]
Thumbnail [72 KiB]
*.C file
mass_Kmumu.pdf

Differential branching fraction of $ B ^+ \!\rightarrow K ^+ \mu ^+\mu ^- $ as a function of the dimuon invariant mass squared, $q^{2}$. The SM theory prediction (see text) is given as the continuous cyan (light) band and the rate-average of this prediction across the $q^{2}$ bin is indicated by the purple (dark) region. No SM prediction is included for the regions close to the narrow $ c \overline c $ resonances.

cWidth.pdf [22 KiB]
HiDef png [161 KiB]
Thumbnail [54 KiB]
*.C file
cWidth.pdf

Dimuon forward-backward asymmetry, $A_{\rm FB}$, and the parameter $F_{\rm H}$ for $ B ^+ \!\rightarrow K ^+ \mu ^+\mu ^- $ as a function of the dimuon invariant mass squared, $ q^2$ . The SM theory prediction (see text) for $F_{\rm H}$ is given as the continuous cyan (light) band and the rate-average of this prediction across the $ q^2$ bin is indicated by the purple (dark) region. No SM prediction is included for the regions close to the narrow $ c \overline c $ resonances.

cAFBzoom.pdf [14 KiB]
HiDef png [68 KiB]
Thumbnail [19 KiB]
*.C file
cAFBzoom.pdf
cFHzoom.pdf [17 KiB]
HiDef png [125 KiB]
Thumbnail [47 KiB] *.C file
cFHzoom.pdf

Animated gif made out of all figures.

PAPER-2012-024.gif
Thumbnail
thumbnail_PAPER-2012-024.gif

Tables and captions

Signal yield ($N_{\text{sig}}$), differential branching fraction ($\mathrm{d}\cal B /\mathrm{d} q^2 $), the parameter $F_{\rm H}$ and dimuon forward-backward asymmetry ($A_{\rm FB}$) for the $ B ^+ \!\rightarrow K ^+ \mu ^+\mu ^- $ decay in the $ q^2$ bins used in the analysis. Results are also given in the $1 < q^2 < 6\mathrm{\,GeV} ^{2}/c^{4}$ range where theoretical uncertainties are best under control.

Table_1.pdf [53 KiB]
HiDef png [94 KiB]
Thumbnail [15 KiB]
tex code
Table_1.pdf

Supplementary Material [file]

Supplementary material full pdf

supple[..].pdf [150 KiB]
supplementary.pdf
Fig1-supp.pdf [24 KiB]
HiDef png [214 KiB]
Thumbnail [69 KiB]
*C file
Fig1-supp.pdf
Fig2-supp.pdf [15 KiB]
HiDef png [98 KiB]
Thumbnail [45 KiB]
*C file
Fig2-supp.pdf

Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.