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Study of $\Xi^-_b$ and $\Omega^-_b$ decays to $\Lambda_c^+ h^- h^{\prime -}$ final states

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Information

Abstract

Decays of $\Xi ^-_ b $ and $\Omega ^-_ b $ baryons to $\Lambda ^+_ c h^- h^{\prime -}$ final states, with $h^- h^{\prime -}$ being $\pi ^- \pi ^- $, $ K ^- \pi ^- $ and $ K ^- K ^- $, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of $8.7 \text{ fb} ^{-1} $ of $pp$ collisions collected at centre-of-mass energies $\sqrt{s} = 7$, $8$ and $13 \text{ Te V} $. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ mode, are measured, with $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- \pi ^- $, $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ and $\Omega ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ being observed at over $5 \sigma$ significance. In addition, the $ B ^- \rightarrow \Lambda ^+_ c \overline p K ^- $ decay is observed for the first time, and its branching fraction is measured relative to that of the $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ mode.

Figures and captions

Example decay diagrams for the (left) $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- \pi ^- $, (centre) $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ and (right) $\Omega ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ channels.

 Xib2Lc[..].pdf [16 KiB]
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Xib2LcKpi_Feyn.pdf
Xib2Lc[..].pdf [16 KiB]
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Xib2LcKK_Feyn.pdf
Omb2Lc[..].pdf [16 KiB]
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Omb2LcKK_Feyn.pdf

Mass distributions of the signal channels with results of the fit superimposed: (top) $\Lambda ^+_ c K ^- K ^- $, (middle) $\Lambda ^+_ c K ^- \pi ^- $ and (bottom) $\Lambda ^+_ c \pi ^- \pi ^- $ for (left) Run I and (right) Run II.

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Xb_fit_KK_Run1_unblind_yields.pdf
Xb_fit[..].pdf [26 KiB]
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Xb_fit_KK_Run2_unblind_yields.pdf
Xb_fit[..].pdf [27 KiB]
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Xb_fit_Kpi_Run1_unblind_yields.pdf
Xb_fit[..].pdf [27 KiB]
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Xb_fit_Kpi_Run2_unblind_yields.pdf
Xb_fit[..].pdf [27 KiB]
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Xb_fit_pipi_Run1_unblind_yields.pdf
Xb_fit[..].pdf [28 KiB]
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Xb_fit_pipi_Run2_unblind_yields.pdf

Mass distributions of the signal channels with results of the fit superimposed: (top) $\Lambda ^+_ c K ^- K ^- $, (middle) $\Lambda ^+_ c K ^- \pi ^- $ and (bottom) $\Lambda ^+_ c \pi ^- \pi ^- $ for (left) Run I and (right) Run II (log scale).

 Xb_fit[..].pdf [22 KiB]
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Xb_fit_KK_Run1_unblind_yields_log.pdf
Xb_fit[..].pdf [23 KiB]
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Xb_fit_KK_Run2_unblind_yields_log.pdf
Xb_fit[..].pdf [23 KiB]
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Xb_fit_Kpi_Run1_unblind_yields_log.pdf
Xb_fit[..].pdf [23 KiB]
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Xb_fit_Kpi_Run2_unblind_yields_log.pdf
Xb_fit[..].pdf [25 KiB]
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Xb_fit_pipi_Run1_unblind_yields_log.pdf
Xb_fit[..].pdf [24 KiB]
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Xb_fit_pipi_Run2_unblind_yields_log.pdf

Mass distributions of the $ B ^- $ modes with results of the fit superimposed: (top) $\Lambda ^+_ c \overline p K ^- $ and (bottom) $\Lambda ^+_ c \overline p \pi ^- $ for (left) Run I and (right) Run II.

 Bu_fit[..].pdf [24 KiB]
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Bu_fit_pK_Run1.pdf
Bu_fit[..].pdf [25 KiB]
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Bu_fit_pK_Run2.pdf
Bu_fit[..].pdf [25 KiB]
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Bu_fit_ppi_Run1.pdf
Bu_fit[..].pdf [26 KiB]
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Bu_fit_ppi_Run2.pdf

Mass distributions of the $ B ^- $ modes with results of the fit superimposed: (top) $\Lambda ^+_ c \overline p K ^- $ and (bottom) $\Lambda ^+_ c \overline p \pi ^- $ for (left) Run I and (right) Run II (log scale).

 Bu_fit[..].pdf [22 KiB]
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Bu_fit_pK_Run1_log.pdf
Bu_fit[..].pdf [24 KiB]
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Bu_fit_pK_Run2_log.pdf
Bu_fit[..].pdf [24 KiB]
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Bu_fit_ppi_Run1_log.pdf
Bu_fit[..].pdf [25 KiB]
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Bu_fit_ppi_Run2_log.pdf

Distributions of (left) $ p_{\mathrm{T}}$ and (right) $\eta$ for $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ decays in (top) Run I and (bottom) Run II, obtained from background-subtracted data and compared to the uncorrected distributions from simulation.

 Bu2ppi[..].pdf [21 KiB]
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Bu2ppiLc_Xb_PT_afterdataMC_comp_Run1.pdf
Bu2ppi[..].pdf [22 KiB]
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Bu2ppiLc_Xb_ETA_afterdataMC_comp_Run1.pdf
Bu2ppi[..].pdf [21 KiB]
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Bu2ppiLc_Xb_PT_afterdataMC_comp_Run2.pdf
Bu2ppi[..].pdf [22 KiB]
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Bu2ppiLc_Xb_ETA_afterdataMC_comp_Run2.pdf

Distributions of (left) $ p_{\mathrm{T}}$ and (right) $\eta$ for $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- \pi ^- $ decays in (top) Run I and (bottom) Run II, obtained from background-subtracted data and compared to the uncorrected distributions from simulation.

 Xib2Kp[..].pdf [21 KiB]
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Xib2KpiLc_Xb_PT_afterdataMC_comp_Run1.pdf
Xib2Kp[..].pdf [21 KiB]
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Xib2KpiLc_Xb_ETA_afterdataMC_comp_Run1.pdf
Xib2Kp[..].pdf [22 KiB]
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Xib2KpiLc_Xb_PT_afterdataMC_comp_Run2.pdf
Xib2Kp[..].pdf [21 KiB]
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Xib2KpiLc_Xb_ETA_afterdataMC_comp_Run2.pdf

Background-subtracted and efficiency-corrected distributions of $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ decays. Top left: $m(\Lambda ^+_ c \pi ^- )$ at low mass, showing the $\Sigma _ c (2455)^0$ resonance peak. Top right: $m(\Lambda ^+_ c \pi ^- )$ at higher mass, showing additional $\Sigma _ c $ resonance structures. Bottom: $m(\Lambda ^+_ c \overline p )$ at low mass, where $m(\Lambda ^+_ c \pi ^- )>2460 \text{ Me V /}c^2 $ has been required to remove reflections from the $\Sigma _ c (2455)^0$ resonance.

 Bu2ppi[..].pdf [16 KiB]
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Bu2ppiLc_InvM23effcorr_veto-Lcpi_Lcpbar_2455.pdf
Bu2ppi[..].pdf [16 KiB]
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Bu2ppiLc_InvM23effcorr_veto-Lcpi_Lcpbar_2840.pdf
Bu2ppi[..].pdf [17 KiB]
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Bu2ppiLc_InvM13effcorr_veto-Lcpi_Lcpbar.pdf

Background-subtracted and efficiency-corrected distributions of $ B ^- \rightarrow \Lambda ^+_ c \overline p K ^- $ decays. Left: $m(\Lambda ^+_ c \overline p )$ at low mass. Right: $m(\Lambda ^+_ c K ^- )$ at low mass, where $m(\Lambda ^+_ c \overline p )>3500 \text{ Me V /}c^2 $ has been required to remove reflections from the $\Lambda ^+_ c \overline p $ threshold enhancement.

 Bu2pKL[..].pdf [17 KiB]
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Bu2pKLc_InvM13effcorr_veto-Lcpi_Lcpbar.pdf
Bu2pKL[..].pdf [16 KiB]
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Bu2pKLc_InvM23effcorr_veto-Lcpi_Lcpbar.pdf

Background-subtracted and efficiency-corrected distributions of $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- \pi ^- $ decays. Left: $m(\Lambda ^+_ c K ^- )$ at low mass. Right: $m(\Lambda ^+_ c \pi ^- )$ at low mass.

 Xib2Kp[..].pdf [16 KiB]
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Xib2KpiLc_InvM13.pdf
Xib2Kp[..].pdf [16 KiB]
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Xib2KpiLc_InvM23.pdf

Variation of the ratio of fragmentation fractions times branching fractions of $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- \pi ^- $ and $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ decays with $b$-hadron transverse momentum and pseudorapidity, separately for Run I and Run II, with statistical uncertainties only.

 BF_xch[..].pdf [13 KiB]
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BF_xcheck_PT_Xib2KpiLc_by_Bu2ppiLc_SU_Kinwgt.pdf
BF_xch[..].pdf [13 KiB]
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BF_xcheck_ETA_Xib2KpiLc_by_Bu2ppiLc_SU_Kinwgt.pdf

Variation of relative branching fraction $ B ^- \rightarrow \Lambda ^+_ c \overline p K ^- $ and $ B ^- \rightarrow \Lambda ^+_ c \overline p \pi ^- $ decays with $b$-hadron transverse momentum and pseudorapidity, separately for Run I and Run II, with statistical uncertainties only.

 BF_xch[..].pdf [14 KiB]
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BF_xcheck_PT_Bu2pKLc_by_Bu2ppiLc_SU_Kinwgt.pdf
BF_xch[..].pdf [14 KiB]
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BF_xcheck_ETA_Bu2pKLc_by_Bu2ppiLc_SU_Kinwgt.pdf

Animated gif made out of all figures.

 CONF-2023-001.gif
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Tables and captions

Fitted yields for $\Xi ^-_ b $ and $\Omega ^-_ b $ decays to the $\Lambda ^+_ c h^- h^{\prime -}$ final states, and for $ B ^- \rightarrow \Lambda ^+_ c \overline p h^-$ decays.

 Table_1.pdf [65 KiB]
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Ratios of fragmentation fractions and branching fractions, separately for Run I and Run II, where in each result the first uncertainty is statistical and the second is systematic.

 Table_2.pdf [87 KiB]
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Significances of the signals for $\Xi ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ and $\Omega ^-_ b \rightarrow \Lambda ^+_ c K ^- K ^- $ decays.

 Table_3.pdf [66 KiB]
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Created on 26 April 2024.