Study of $B_s^0 \to J/\psi \pi^+ \pi^- K^+ K^-$ decays

Information

LHCb-PAPER-2020-035
CERN-EP-2020-192
arXiv:2011.01867 [PDF]

(Submitted on 03 Nov 2020)
JHEP 02 (2021) 024
Inspire 1827842

Tools

Abstract

The decays $B^0_s \rightarrow J/\psi \pi^+\pi^- K^+ K^-$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$, collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13TeV. The decays $B^0_s \rightarrow J/\psi K^{\ast0} \bar{K}^{\ast0}$ and $B^0_s \rightarrow \chi_{c1}(3872)K^+K^-$, where the $K^+K^-$ pair does not originate from a $\phi$ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate $\chi_{c1}(3872)\phi$, $J/\psi K^{\ast0}\bar{K}^{\ast0}$, $\psi(2S)\phi$ and $\chi_{c1}(3872)K^+K^-$ states are reported. A structure, denoted as $X(4740)$, is observed in the $J/\psi\phi$ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be \begin{eqnarray*} m_{X(4740)} & = & 4741 \pm 6 \pm 6 {\mathrm{MeV}}/c^2 , \\ \Gamma_{X(4740)} & = & 53 \pm 15 \pm 11 {\mathrm{MeV}} , \end{eqnarray*} where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the $B^0_s$ meson is performed and gives a value of $$ m_{B^0_s} = 5366.98 \pm 0.07 \pm 0.13 {\mathrm{MeV}}/c^2 . $$

Figures and captions

Distribution of the $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $ mass of selected $ B ^0_ s $ candidates shown as points with error bars. A fit, described in the text, is overlaid.	Fig_1.pdf [155 KiB] HiDef png [302 KiB] Thumbnail [172 KiB] *.C file tex code
Distributions of the (top left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $, (top right) $ K ^+ K ^- $ and (bottom left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ mass of selected $ B ^0_ s \rightarrow \chi _{ c 1} (3872)\phi $ candidates shown as points with error bars. A fit, described in the text, is overlaid.	Fig_2.pdf [238 KiB] HiDef png [676 KiB] Thumbnail [344 KiB] *.C file tex code
Distributions of the (top left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $, (top right) $ K ^+ K ^- $ and (bottom left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ mass of selected $ B ^0_ s \rightarrow \psi {(2 S )} \phi $ candidates shown as points with error bars. A fit, described in the text, is overlaid.	Fig_3.pdf [233 KiB] HiDef png [590 KiB] Thumbnail [306 KiB] *.C file tex code
Distributions of the (left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $ and (right) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ mass of selected $ B ^0_ s \rightarrow \chi _{ c 1} (3872) K ^+ K ^- $ candidates shown as points with error bars. A fit, described in the text, is overlaid.	Fig_4.pdf [168 KiB] HiDef png [449 KiB] Thumbnail [249 KiB] *.C file tex code
Background-subtracted and efficiency-corrected $ K ^+ K ^- $ mass distribution (points with error bars) of the $ B ^0_ s \rightarrow \chi _{ c 1} (3872) K ^+ K ^- $ decays. For a better visualisation, the highdash-mass region the plot is shown with a reduced vertical scale. A fit, described in the text, is overlaid. The expectation for phasedash-space simulated decays is shown as a green solid line. A distribution with extended vertical scale is shown inset.	Fig_5.pdf [218 KiB] HiDef png [427 KiB] Thumbnail [261 KiB] *.C file tex code
Distributions of the (top left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $, (top right) $ K ^+ \pi ^- $ and (bottom left) $ K ^- \pi ^+ $ mass of selected $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } K ^{0} \overline{ K } {}^{0} $ candidates shown as points with error bars. A fit, described in the text, is overlaid.	Fig_6.pdf [239 KiB] HiDef png [650 KiB] Thumbnail [329 KiB] *.C file tex code
Distribution of the $\psi {(2 S )} K ^+ K ^- $ mass for selected $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } K ^+ K ^- \pi ^+ \pi ^- $ candidates, enriched in $ B ^0_ s \rightarrow \left(\psi {(2 S )} \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \right) \left( \phi \rightarrow K ^+ K ^- \right) $ decays (points with error bars). A fit, described in the text, is overlaid.	Fig_7.pdf [132 KiB] HiDef png [281 KiB] Thumbnail [156 KiB] *.C file tex code
Distribution of the (left) $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- K ^+ K ^- $ and (right) $ K ^+ K ^- $ mass for selected $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \phi $ candidates. A fit, described in the text, is overlaid.	Fig_8.pdf [166 KiB] HiDef png [398 KiB] Thumbnail [209 KiB] *.C file tex code
Background-subtracted (left) $ { J \mskip -3mu/\mskip -2mu\psi } \phi $ and (right) $\phi \pi ^+ \pi ^- $ mass distributions from $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \phi $ decays (points with error bars). The expectation from simulated $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \phi $ decays is overlaid (green solid line). In the right figure, the background-subtracted $\phi \pi ^+ \pi ^- $ mass distribution in the region $4.68<m_{ { J \mskip -3mu/\mskip -2mu\psi } \phi }<4.78\text{ Ge V /}c^2 $ is shown (red open circles with error bars) together with the corresponding expectation from simulated $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \phi $ decays (blue dashed line).	Fig_9.pdf [147 KiB] HiDef png [282 KiB] Thumbnail [173 KiB] *.C file tex code
Background-subtracted $ { J \mskip -3mu/\mskip -2mu\psi } \phi $ mass distribution from $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \phi $ decays (points with error bars). A fit, described in the text, is overlaid.	Fig_10.pdf [137 KiB] HiDef png [334 KiB] Thumbnail [207 KiB] *.C file tex code
Animated gif made out of all figures.	PAPER-2020-035.gif Thumbnail

Tables and captions

Signal yields, $N_{ B ^0_ s \rightarrow X _{ c \overline c }\phi }$, mass of the $ B ^0_ s $ meson, $m_{ B ^0_ s }$, and detector resolution scale factors, $s_{ B ^0_ s }$ and $s_{ X _{ c \overline c }}$, from the fit described in the text. The uncertainties are statistical only.	Table_1.pdf [113 KiB] HiDef png [44 KiB] Thumbnail [21 KiB] tex code
Signal yield, $N_{ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } K ^{0} \overline{ K } {}^{0} }$, and mass of the $ B ^0_ s $ meson, $m_{ B ^0_ s }$, from the fit described in the text. The uncertainties are statistical only.	Table_2.pdf [121 KiB] HiDef png [60 KiB] Thumbnail [27 KiB] tex code
Signal yield, $N_{ B ^0_ s }$ and mass of the $ B ^0_ s $ meson, $m_{ B ^0_ s }$, from the fit described in the text to the sample enriched in the $ B ^0_ s \rightarrow \psi {(2 S )} \phi $ decays. The uncertainties are statistical only.	Table_3.pdf [102 KiB] HiDef png [41 KiB] Thumbnail [19 KiB] tex code
Signal yield $N_{ X (4740)}$, mass $m_{ X (4740)}$ and width $\Gamma_{ X (4740)}$ of the $ X (4740)$ structure, obtained from the fit to the backgrounddash-subtracted $ { J \mskip -3mu/\mskip -2mu\psi } \phi $ mass distribution. The uncertainties are statistical only.	Table_4.pdf [88 KiB] HiDef png [54 KiB] Thumbnail [26 KiB] tex code
Relative systematic uncertainties (in %) for the ratios of branching fractions. The sources are described in the text.	Table_5.pdf [98 KiB] HiDef png [55 KiB] Thumbnail [26 KiB] tex code
Systematic uncertainties on the $ B ^0_ s $ mass measurement using the sample enriched in the $ B ^0_ s \rightarrow \psi {(2 S )} \phi $ decays. The sources are described in the text.	Table_6.pdf [95 KiB] HiDef png [74 KiB] Thumbnail [33 KiB] tex code
Systematic uncertainties for the measurements of the mass and width of the $ X (4740)$ structure. The sources are described in the text.	Table_7.pdf [96 KiB] HiDef png [42 KiB] Thumbnail [19 KiB] tex code