cern.ch

Measurements of the Branching fractions for $B_{(s)} \to D_{(s)}\pi\pi\pi$ and $\Lambda_b^0 \to \Lambda_c^+\pi\pi\pi$

[to restricted-access page]

Abstract

Branching fractions of the decays $H_b\to H_c\pi^-\pi^+\pi^-$ relative to $H_b\to H_c\pi^-$ are presented, where $H_b$ ($H_c$) represents B^0-bar($D^+$), $B^-$ ($D^0$), B_s^0-bar ($D_s^+$) and $\Lambda_b^0$ ($\Lambda_c^+$). The measurements are performed with the LHCb detector using 35${\rm pb^{-1}}$ of data collected at $\sqrt{s}=7$ TeV. The ratios of branching fractions are measured to be B(B^0-bar -> D^+\pi^-\pi^+\pi^-)/ B(B^0-bar -> D^+\pi^-) = 2.38\pm0.11\pm0.21 B(B^- -> D^0\pi^-\pi^+\pi^-) / B(B^- -> D^0\pi^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -> D_s^+\pi^-\pi^+\pi^-) / B(B_s^0-bar -> D_s^+\pi^-) = 2.01\pm0.37\pm0.20 B(\Lambda_b^0->\Lambda_c^+\pi^-\pi^+\pi^-) / B(\Lambda_b^0 -> \Lambda_c^+\pi^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements.

Figures and captions

Feynman diagrams for $H_b\rightarrow H_c\pi^-$ and $H_b\rightarrow H_c\pi^-\pi^+\pi^-$ decays. Figs. (a) and (b) show external tree diagrams, (c) and (d) show color-suppressed tree diagrams ($B^-$ and $\Lambda_b^0$ only), and (e) shows the Cabibbo-suppressed external tree diagram, only accessible to $B^0$ meson.

TreeB2[..].eps [9 KiB]
HiDef png [75 KiB]
Thumbnail [26 KiB]
*.C file
TreeB2D0PiDecayCF.eps
Lb2LcP[..].eps [7 KiB]
HiDef png [60 KiB]
Thumbnail [19 KiB] *.C file
Lb2LcPiDecayExternal.eps
TreeB2[..].eps [7 KiB]
HiDef png [52 KiB]
Thumbnail [18 KiB] *.C file
TreeB2D0PiDecayCS.eps
Lb2LcP[..].eps [8 KiB]
HiDef png [62 KiB]
Thumbnail [20 KiB] *.C file
Lb2LcPiDecayInternal.eps
TreeB2[..].eps [7 KiB]
HiDef png [57 KiB]
Thumbnail [20 KiB] *.C file
TreeB2DPiDecayCS.eps

Invariant mass distributions for $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ (top left), $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ (top right), $\overline{ B }{} ^0_s \rightarrow D_s^+\pi^-\pi^+\pi^-$ (bottom left), and $\Lambda_b^0\rightarrow \Lambda_c^+\pi^-\pi^+\pi^-$ (bottom right). Fits showing the signal and background components are indicated, and are described in the text.

b2dcha[..].eps [21 KiB]
HiDef png [223 KiB]
Thumbnail [85 KiB]
*.C file
b2dcha1_trigsel_35pb_Paper.eps
b2d0a1[..].eps [26 KiB]
HiDef png [246 KiB]
Thumbnail [94 KiB] *.C file
b2d0a1_trigsel_35pb_Paper.eps
bs2dsa[..].eps [25 KiB]
HiDef png [275 KiB]
Thumbnail [107 KiB] *.C file
bs2dsa1_trigsel_35pb_Paper.eps
lb2lca[..].eps [28 KiB]
HiDef png [245 KiB]
Thumbnail [94 KiB] *.C file
lb2lca1_trigsel_35pb_Paper.eps

Invariant mass distributions for $\overline{ B }{} ^0 \rightarrow D^+\pi^-$ (top left), $B^{-}\rightarrow D^0\pi^{-}$ (top right), $\overline{ B }{} ^0_s \rightarrow D_s^+\pi^-$ (bottom left), and $\Lambda_b^0\rightarrow \Lambda_c^+\pi^-$ (bottom right). Fits showing the signal and background components are indicated, and are described in the text.

b2dpi_[..].eps [29 KiB]
HiDef png [219 KiB]
Thumbnail [81 KiB]
*.C file
b2dpi_trigsel_35pb_Paper.eps
b2d0pi[..].eps [30 KiB]
HiDef png [230 KiB]
Thumbnail [86 KiB] *.C file
b2d0pi_trigsel_35pb_Paper.eps
bs2dsp[..].eps [24 KiB]
HiDef png [266 KiB]
Thumbnail [103 KiB] *.C file
bs2dspi_trigsel_35pb_Paper.eps
lb2lcp[..].eps [21 KiB]
HiDef png [227 KiB]
Thumbnail [86 KiB] *.C file
lb2lcpi_trigsel_35pb_Paper.eps

Comparisons of the $p_T$ and IP spectra for the daughters from the $D^+$ in $\overline{ B }{} ^0 \rightarrow D^+\pi^-$ [(a) and (b)], and from the $D^+$ in $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ [(c) and (d)]; Points with error bars are data and the solid lines are simulation.

ddau_H[..].eps [19 KiB]
HiDef png [152 KiB]
Thumbnail [49 KiB]
*.C file
ddau_H_paper.eps
ddau_3[..].eps [21 KiB]
HiDef png [166 KiB]
Thumbnail [54 KiB] *.C file
ddau_3H_paper.eps

Comparisons of the $p_T$ and IP spectra for the bachelor pion in $\overline{ B }{} ^0 \rightarrow D^+\pi^-$ [(a) and (b)], and for the 3 pions in $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ [(c) and (d)]. Points with error bars are data and the solid lines are simulation.

kdau_H[..].eps [20 KiB]
HiDef png [164 KiB]
Thumbnail [54 KiB]
*.C file
kdau_H_paper.eps
kdau_3[..].eps [20 KiB]
HiDef png [161 KiB]
Thumbnail [54 KiB] *.C file
kdau_3H_paper.eps

Invariant mass of the $3\pi$ system in $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ (top left), $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ (top right), $\overline{ B }{} ^0_s \rightarrow D_s^+\pi^-\pi^+\pi^-$ (bottom left) and $\Lambda_b^0\rightarrow \Lambda_c^+\pi^-\pi^+\pi^-$ (bottom right) decays. The data are the points with error bars and the simulations are the solid lines and shaded regions.

PiPiPi[..].eps [14 KiB]
HiDef png [184 KiB]
Thumbnail [30 KiB]
*.C file
PiPiPiMass_B2DA1.eps
PiPiPi[..].eps [14 KiB]
HiDef png [192 KiB]
Thumbnail [32 KiB] *.C file
PiPiPiMass_B2D0A1.eps
PiPiPi[..].eps [12 KiB]
HiDef png [173 KiB]
Thumbnail [70 KiB] *.C file
PiPiPiMass_Bs2DsA1.eps
PiPiPi[..].eps [14 KiB]
HiDef png [230 KiB]
Thumbnail [35 KiB] *.C file
PiPiPiMass_Lb2LcA1.eps

$\pi^+\pi^-$ invariant mass (2 combinations per $\overline{ B }{} ^0 $ candidate) in the $3\pi$ system for $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ when (a) $M(\pi^-\pi^+\pi^-)<1.5$ GeV/$c^2$ and (b) $M(\pi^-\pi^+\pi^-)\ge 1.5$ GeV/$c^2$. The corresponding plots for $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ are shown in (c) and (d).

pipiMa[..].eps [16 KiB]
HiDef png [152 KiB]
Thumbnail [49 KiB]
*.C file
pipiMass_B2DA1.eps
pipiMa[..].eps [16 KiB]
HiDef png [152 KiB]
Thumbnail [49 KiB] *.C file
pipiMass_B2D0A1.eps

Invariant mass difference $M(D\pi^-\pi^+) - M(D)$, for (a) $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$ signal candidates, (b) $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ signal candidates, (c) $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ through a $D^{*+}$ intermediate state, and (d) $B^-\rightarrow D^0\pi^-\pi^+\pi^-$ not through a $D^{*+}$ intermediate state. The signal components are the white region (and lightly shaded regions for $B^-\rightarrow D^0\pi^-\pi^+\pi^-$), and the background component is the darker shaded region.

B02D3P[..].eps [18 KiB]
HiDef png [211 KiB]
Thumbnail [81 KiB]
*.C file
B02D3Pi_ExcCharm_Trig_Paper.eps
Bp2D03[..].eps [19 KiB]
HiDef png [228 KiB]
Thumbnail [84 KiB] *.C file
Bp2D03Pi_ExcCharm_Trig_Paper.eps
Bp2D03[..].eps [20 KiB]
HiDef png [235 KiB]
Thumbnail [88 KiB] *.C file
Bp2D03Pi_ExcCharmDStar_TrigSel_Paper.eps
Bp2D03[..].eps [19 KiB]
HiDef png [234 KiB]
Thumbnail [87 KiB] *.C file
Bp2D03Pi_ExcCharmnonDStar_TrigSel_Paper.eps

Intermediate resonances contributing to the $\Lambda_b^0\rightarrow \Lambda_c^+\pi^-\pi^+\pi^-$ decay. Shown are distributions for (a) $M(\Lambda_c^+\pi^-\pi^+) - M(\Lambda_c^+)$, with $\Lambda_c(2595)^+$ and $\Lambda_c(2625)^+$ contributions, (b) $M(\Lambda_c^+\pi^{\pm}) - M(\Lambda_c^+)$ (3 combinations per $\Lambda_b^0$ candidate) (c) $M(\Lambda_c^+\pi^{-}) - M(\Lambda_c^+)$ (2 combinations per $\Lambda_b^0$ candidate), and (d) $M(\Lambda_c^+\pi^{+}) - M(\Lambda_c^+)$ (1 combination per $\Lambda_b^0$ candidate), showing the intermediate $\Sigma_c$ states. The line is a fit as described in the text, and the shaded region is the fitted background.

Lb2Lc3[..].eps [24 KiB]
HiDef png [221 KiB]
Thumbnail [82 KiB]
*.C file
Lb2Lc3pi_Lcpipi_Trig.eps
Lb2Lc3[..].eps [26 KiB]
HiDef png [206 KiB]
Thumbnail [81 KiB] *.C file
Lb2Lc3piTrigSel_SigmaCpipi.eps
Lb2Lc3[..].eps [26 KiB]
HiDef png [208 KiB]
Thumbnail [82 KiB] *.C file
Lb2Lc3piTrigSel_SigmaC0pipi.eps
Lb2Lc3[..].eps [25 KiB]
HiDef png [206 KiB]
Thumbnail [76 KiB] *.C file
Lb2Lc3piTrigSel_SigmaCpppipi.eps

Animated gif made out of all figures.

PAPER-2011-016.gif
Thumbnail
thumbnail_PAPER-2011-016.gif

Tables and captions

Summary of efficiencies for decay channels under study. Here, $\epsilon_{\rm kin}$ is the total kinematic selection efficiency, $\epsilon_{\rm trig}$ is the trigger efficiency, and $\epsilon_{\rm tot}$ is their product. The uncertainties shown are statistical only.

Table_1.pdf [52 KiB]
HiDef png [99 KiB]
Thumbnail [16 KiB]
tex code
Table_1.pdf

Summary of yields for the branching fraction computation. Uncertainties are statistical only.

Table_2.pdf [50 KiB]
HiDef png [50 KiB]
Thumbnail [9 KiB]
tex code
Table_2.pdf

Summary of corrections and systematic uncertainties to the ratio of branching fractions $\cal{B}(H_b\rightarrow H_c\pi^-\pi^+\pi^-)/\cal{B}(H_b\rightarrow H_c\pi^-)$.

Table_3.pdf [57 KiB]
HiDef png [85 KiB]
Thumbnail [12 KiB]
tex code
Table_3.pdf

Summary of yields for the signal and normalization modes. Below $D_1$ and $D_2^*$ refer to the $D_1(2420)$ and $D_2^*(2460)$ mesons, respectively.

Table_4.pdf [54 KiB]
HiDef png [103 KiB]
Thumbnail [17 KiB]
tex code
Table_4.pdf

Summary of the relative reconstruction and selection efficiencies ($\epsilon_{\rm sel}^{\rm rel}$) and trigger efficiencies ($\epsilon_{\rm trig|sel}^{\rm rel}$) for the excited charm hadron intermediate states with respect to the inclusive $H_c\pi^-\pi^+\pi^-$ final states. Below $D_1$ and $D_2^*$ refer to $D_1(2420)$ and $D_2^*(2460)$, respectively. The uncertainties shown are statistical only.

Table_5.pdf [54 KiB]
HiDef png [76 KiB]
Thumbnail [12 KiB]
tex code
Table_5.pdf

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