Study of the rare $B_s^0$ and $B^0$ decays into the $\pi^+\pi^-\mu^+\mu^-$ final state

Information

LHCb-PAPER-2014-063
CERN-PH-EP-2014-296
arXiv:1412.6433 [PDF]

(Submitted on 19 Dec 2014)
Phys. Lett. B743 (2015) 46
Inspire 1335137

Tools

Abstract

A search for the rare decays $B_s^0 \to \pi^+\pi^-\mu^+\mu^-$ and $B^0 \to \pi^+\pi^-\mu^+\mu^-$ is performed in a data set corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/$c^2$ and with muon pairs that do not originate from a resonance are considered. The first observation of the decay $B_s^0 \to \pi^+\pi^-\mu^+\mu^-$ and the first evidence of the decay $B^0 \to \pi^+\pi^-\mu^+\mu^-$ are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be $\mathcal{B}(B_s^0 \to \pi^+\pi^-\mu^+\mu^-)=(8.6\pm 1.5 ({\rm stat}) \pm 0.7 ({\rm syst})\pm 0.7 ({\rm norm}))\times 10^{-8}$ and $\mathcal{B}(B^0 \to \pi^+\pi^-\mu^+\mu^-)=(2.11\pm 0.51 ({\rm stat}) \pm 0.15 ({\rm syst})\pm 0.16 ({\rm norm}) )\times 10^{-8}$, where the third uncertainty is due to the branching fraction of the decay $B^0\to J/\psi(\to \mu^+\mu^-)K^*(890)^0(\to K^+\pi^-)$, used as a normalisation.

Figures and captions

Mass distribution of $ { B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K^{*}(892)^0 }$ candidates with fit projections overlaid. The 2011 and 2012 data sets are combined.	Fig1.pdf [24 KiB] HiDef png [307 KiB] Thumbnail [249 KiB] *.C file
Mass distributions of (a) the $ { B_{(s)}^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+\pi^- }$ and (b) the $ { B_{(s)}^0 \rightarrow \pi^+\pi^-\mu^+\mu^- }$ \ decay candidates in the range 5.19--5.99 $ {\mathrm{ Ge V /}c^2}$ with fit projections overlaid. The 2011 and 2012 data sets are combined. In (b), the contribution from ${ B ^0_ s \rightarrow \phi \mu^+\mu^- }$ and ${ B ^+ \rightarrow K^+ \mu^+\mu^- }$ decays are included in the fit, but they are not visible in the projection, because the corresponding yields are small.	Fig2a.pdf [25 KiB] HiDef png [351 KiB] Thumbnail [277 KiB] *.C file
	Fig2b.pdf [19 KiB] HiDef png [284 KiB] Thumbnail [224 KiB] *.C file
Background-subtracted distributions of the $\pi^+\pi^-$ invariant mass for (a) $ { B ^0_ s \rightarrow \pi^+\pi^-\mu^+\mu^- }$ and (b) $ { B ^0 \rightarrow \pi^+\pi^-\mu^+\mu^- }$ candidates (triangular markers). The uncertainties are statistical only. The data are compared with the background-subtracted $\pi^+\pi^-$ mass distributions of (a) $ { B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+\pi^- }$ and (b) $ { B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+\pi^- }$ candidates (histograms).	Fig3a.pdf [14 KiB] HiDef png [148 KiB] Thumbnail [132 KiB] *.C file
	Fig3b.pdf [14 KiB] HiDef png [143 KiB] Thumbnail [129 KiB] *.C file
Animated gif made out of all figures.	PAPER-2014-063.gif Thumbnail

Tables and captions

Selection efficiencies of the 2011 and 2012 data sets; $\varepsilon_s$ for the $ { B ^0_ s \rightarrow \pi^+\pi^-\mu^+\mu^- }$ decay, $\varepsilon_d$ for the $ { B ^0 \rightarrow \pi^+\pi^-\mu^+\mu^- }$ decay, and $\varepsilon_n$ for the $ { B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K^{*}(892)^0 }$ decay.	Table_1.pdf [35 KiB] HiDef png [46 KiB] Thumbnail [21 KiB] tex code
Summary of systematic uncertainties on $\mathcal{R}_{s}$ and $\mathcal{R}_{d}$ .	Table_2.pdf [54 KiB] HiDef png [83 KiB] Thumbnail [37 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [278 KiB]
This ZIP file contains supplementary material for the publication LHCb-PAPER-2014-063. The files are: Supplementary.pdf: An overview of the extra figure .pdf, .png, .eps, .C: The figures in various formats. The *.C files contain the data on the figures.	Fig1.pdf [20 KiB] HiDef png [276 KiB] Thumbnail [197 KiB] *C file
	Fig2.pdf [14 KiB] HiDef png [146 KiB] Thumbnail [136 KiB] *C file
	Fig3.pdf [54 KiB] HiDef png [1010 KiB] Thumbnail [837 KiB] *C file
	Fig4.pdf [55 KiB] HiDef png [1 MiB] Thumbnail [590 KiB] *C file
	Fig5.pdf [14 KiB] HiDef png [119 KiB] Thumbnail [113 KiB] *C file
	Fig6a.pdf [13 KiB] HiDef png [103 KiB] Thumbnail [74 KiB] *C file
	Fig6b.pdf [13 KiB] HiDef png [105 KiB] Thumbnail [73 KiB] *C file
	Fig7.pdf [22 KiB] HiDef png [273 KiB] Thumbnail [200 KiB] *C file