Search for decays of neutral beauty mesons into four muons

Information

LHCb-PAPER-2016-043
CERN-EP-2016-276
arXiv:1611.07704 [PDF]

(Submitted on 23 Nov 2016)
JHEP 03 (2017) 001
Inspire 1499874

Tools

Abstract

A search for the non-resonant decays $B^0_s \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}$ and $B^0 \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}$ is presented. The measurement is performed using the full Run 1 data set collected in proton-proton collisions by the LHCb experiment at the LHC. The data correspond to integrated luminosities of $1$ and $2 \mathrm{fb}^{-1}$ collected at centre-of-mass energies of $7$ and $8 \mathrm{TeV}$, respectively. No signal is observed and upper limits on the branching fractions of the non-resonant decays at $95\%$ confidence level are determined to be \mathcal{B}(B^0_s \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}) & < 2.5 \times 10^{-9} \mathcal{B}(B^0 \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}) & < 6.9 \times 10^{-10}.

Figures and captions

Feynman diagrams for \subref{subfig:nonResoFMD} the non-resonant $ B ^0_{( s )} \rightarrow \mu ^+\mu ^- \mu ^+\mu ^- $ decay, \subref{subfig:NPFMD} a supersymmetric $ B ^0_{( s )} \rightarrow S (\rightarrow \mu ^+\mu ^- ) P (\rightarrow \mu ^+\mu ^- )$ decay and \subref{subfig:ResoFMD} the resonant $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} (\rightarrow \mu ^+\mu ^- )\phi (\rightarrow \mu ^+\mu ^- )$ decay (see text).	B24muN[..].pdf [34 KiB] HiDef png [43 KiB] Thumbnail [26 KiB] *.C file
	B24muNP.pdf [32 KiB] HiDef png [34 KiB] Thumbnail [21 KiB] *.C file
	B24muR[..].pdf [32 KiB] HiDef png [69 KiB] Thumbnail [50 KiB] *.C file
Fit to the $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} (\rightarrow \mu ^+\mu ^- ) K ^+ $ invariant mass distribution. The signal contribution is modelled by a Hypatia2 [26] function (blue dotted line), the combinatorial background by an exponential function (green dash-dotted line). Partially reconstructed decays, such as $ B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^{*0} $ where one pion is not reconstructed, are modelled by a Gaussian function with an exponential tail towards the lower mass side (red dashed line). Data are shown by black dots.	jpsik_[..].pdf [37 KiB] HiDef png [201 KiB] Thumbnail [160 KiB] *.C file
Mass distribution of selected $ B ^0_{( s )} \rightarrow \mu ^+\mu ^- \mu ^+\mu ^- $ events observed in 3 $ fb^{-1}$ of data in all considered $ B $ mass regions. Background (red line) is modelled by an exponential function. Signal subregions for $ B ^0$ and $ B ^0_ s $ searches are also shown. The error bars on the individual points with $n$ entries are $\pm\sqrt{n}$.	evalua[..].pdf [28 KiB] HiDef png [832 KiB] Thumbnail [436 KiB] *.C file
Expected and observed 95% CL exclusion in $\mathcal{B}$ ( $ B ^0 \rightarrow \mu ^+\mu ^- \mu ^+\mu ^- $ ) vs. $\mathcal{B}$ ( $ B ^0_ s \rightarrow \mu ^+\mu ^- \mu ^+\mu ^- $ ) parameters plane.	bsd24mu.pdf [17 KiB] HiDef png [993 KiB] Thumbnail [365 KiB] *.C file
Expected and observed 95% CL exclusion in $\mathcal{B}$ ( $ B ^0 \rightarrow S (\rightarrow \mu ^+\mu ^- ) P (\rightarrow \mu ^+\mu ^- )$ ) vs. $\mathcal{B}$ ( $ B ^0_ s \rightarrow S (\rightarrow \mu ^+\mu ^- ) P (\rightarrow \mu ^+\mu ^- )$ ) parameters plane with scalar and pseudoscalar S and P as described in Sec. 3.	bsd24muNP.pdf [17 KiB] HiDef png [878 KiB] Thumbnail [374 KiB] *.C file
Animated gif made out of all figures.	PAPER-2016-043.gif Thumbnail

Tables and captions

Definitions of intervals in the $ B ^0$ and $ B ^0_ s $ reconstructed invariant mass distributions.	Table_1.pdf [45 KiB] HiDef png [101 KiB] Thumbnail [44 KiB] tex code
Summary of systematic uncertainties affecting the single event sensitivities along with the total systematic uncertainty calculated by adding up the individual components in quadrature. The dominating uncertainty arising from $f_ u / f_ s $ only contributes to $\eta_s$. The uncertainty of the stated selection efficiencies arising from the limited number of simulated events is 0.5% for $ B ^0 \rightarrow \mu ^+\mu ^- \mu ^+\mu ^- $ and 0.4% for all other considered decay modes.	Table_2.pdf [59 KiB] HiDef png [177 KiB] Thumbnail [84 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [339 KiB]
This ZIP file contains supplemetary material for the publication LHCB-PAPER-2016-043. The files are: Supplementary.pdf : An overview of the extra figures *.pdf : The figures in variuous formats	Fig1a-S.pdf [30 KiB] HiDef png [278 KiB] Thumbnail [149 KiB] *C file
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