Studies of the decays $B^+ \to p \bar p h^+$ and observation of $B^+ \to \bar{\Lambda}(1520)p$

Information

LHCb-PAPER-2013-031
CERN-PH-EP-2013-125
arXiv:1307.6165 [PDF]

(Submitted on 23 Jul 2013)
Phys. Rev. D88 (2013) 052015
Inspire 1244131

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Abstract

Dynamics and direct $C\P$ violation in three-body charmless decays of charged $B$ mesons to a proton, an antiproton and a light meson (pion or kaon) are studied using data, corresponding to an integrated luminosity of 1.0$ { fb}^{-1}$, collected by the ${LHCb}$ experiment in $pp$ collisions at a center-of-mass energy of 7 TeV. Production spectra are determined as a function of Dalitz-plot and helicity variables. The forward-backward asymmetry of the light meson in the $p\bar p$ rest frame is measured. No significant $C\P$ asymmetry in $B^+ \to p \bar p K^+$ decay is found in any region of the Dalitz plane. We present the first observation of the decay $B^+ \to \bar{\Lambda}(1520)(\to K^+\bar p)p$ near the $K^+\bar p$ threshold and measure $\mathcal{B}(B^+ \to \bar{\Lambda}(1520)p)=(3.9^{+1.0}_{-0.9} (\mathrm{stat})\pm0.1 (\mathrm{syst})\pm0.3 (\mathrm{BF}))\times 10^{-7}$, where BF denotes the uncertainty on secondary branching fractions.

Figures and captions

Leading tree and penguin diagrams for $ B^+ \rightarrow p \overline p h^+$ decays.	Fig1a.pdf [13 KiB] HiDef png [42 KiB] Thumbnail [22 KiB] *.C file
	Fig1b.pdf [16 KiB] HiDef png [52 KiB] Thumbnail [27 KiB] *.C file
Invariant mass distributions of (left) $p\overline p K ^+ $ and (right) $p\overline p \pi ^+ $ candidates. The points with error bars represent data. The solid black line represents the total fit function. Blue dashed, purple dotted, red long-dashed and green dashed-dotted curves represent the signal, cross-feed, combinatorial background and partially reconstructed background, respectively.	Fig2a.pdf [19 KiB] HiDef png [176 KiB] Thumbnail [158 KiB] *.C file
	Fig2b.pdf [19 KiB] HiDef png [168 KiB] Thumbnail [154 KiB] *.C file
Efficiency-corrected differential yield as a function of $m_{p\overline p }$ for (left) $ B^+ \rightarrow p \overline p K ^+ $ and (right) $ B^+ \rightarrow p \overline p \pi ^+ $ . The data points are shown with their statistical and total uncertainties. For comparison, the solid lines represent the expectations for a uniform phase space production, normalized to the efficiency-corrected area.	Fig3a.pdf [14 KiB] HiDef png [99 KiB] Thumbnail [111 KiB] *.C file
	Fig3b.pdf [14 KiB] HiDef png [92 KiB] Thumbnail [102 KiB] *.C file
Efficiency-corrected differential yield as a function of $m_{Kp}^2$ for $ B^+ \rightarrow p \overline p K ^+ $ . The data points are shown with their statistical and total uncertainties. The solid line represents the expectation for a uniform phase space production, normalized to the efficiency-corrected area, for comparison.	Fig4.pdf [14 KiB] HiDef png [112 KiB] Thumbnail [123 KiB] *.C file
Efficiency-corrected differential yields as functions of $\cos\theta_p$ for (left) $ B^+ \rightarrow p \overline p K ^+ $ and (right) $ B^+ \rightarrow p \overline p \pi ^+ $ modes, after subtraction of the charmonium contributions. The data points are shown with their statistical and total uncertainties.	Fig5a.pdf [14 KiB] HiDef png [71 KiB] Thumbnail [45 KiB] *.C file
	Fig5b.pdf [14 KiB] HiDef png [78 KiB] Thumbnail [46 KiB] *.C file
Signal weighted Dalitz-plot distributions for (left) $ B^+ \rightarrow p \overline p K ^+ $ and (right) $ B^+ \rightarrow p \overline p \pi ^+ $ . Also shown are the iso-$\cos\theta_p$ lines corresponding to the $\cos\theta_p$ bin boundaries; $\cos\theta_p=-1$ (+1) is the uppermost (lowermost) line. The distributions are not corrected for efficiency.	Fig6a.pdf [25 KiB] HiDef png [455 KiB] Thumbnail [372 KiB] *.C file
	Fig6b.pdf [23 KiB] HiDef png [417 KiB] Thumbnail [364 KiB] *.C file
Distribution of $ A_{ C P }$ for the Dalitz-plot projections on $m_{p\overline p }$ and $m_{Kp}^2$ for $ B ^\pm \rightarrow p \overline p K^{\pm}$ events. In the $m_{p\overline p }$ projection (left), the bin $[2.85,3.15] {\mathrm{ Ge V /}c^2} $ contains only the value of the charmless $p\overline p K ^\pm $ after subtraction of the $\eta _ c $ - $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ contribution. The $m_{Kp}^2$ projection (right) has been obtained after removing the charmonia bands.	Fig7a.pdf [15 KiB] HiDef png [77 KiB] Thumbnail [48 KiB] *.C file
	Fig7b.pdf [14 KiB] HiDef png [82 KiB] Thumbnail [53 KiB] *.C file
Invariant mass $m_{Kp}$ for the $ B^+ \rightarrow p \overline p K ^+ $ candidates near threshold.	Fig8.pdf [18 KiB] HiDef png [117 KiB] Thumbnail [80 KiB] *.C file
Fit to the $B$ signal weighted $m_{Kp}$ distribution.	Fig9.pdf [15 KiB] HiDef png [139 KiB] Thumbnail [133 KiB] *.C file
Projections of (left) $m_{Kp}$ and (right) $m_{p\overline p K ^+ }$ of the two dimensional fit used to obtain the $ B^+ \rightarrow \overline{\Lambda} (1520)p$ signal yield.	Fig10a.pdf [15 KiB] HiDef png [129 KiB] Thumbnail [127 KiB] *.C file
	Fig10b.pdf [18 KiB] HiDef png [163 KiB] Thumbnail [166 KiB] *.C file
Animated gif made out of all figures.	PAPER-2013-031.gif Thumbnail

Tables and captions

Fitted $ B^+ \rightarrow p \overline p K ^+ $ signal yield, including the charmonium modes, efficiency and relative systematic uncertainty, in bins of $p\overline p $ invariant mass. The error on the efficiency includes all the sources of uncertainty.	Table_1.pdf [46 KiB] HiDef png [91 KiB] Thumbnail [47 KiB] tex code
Fitted $ B^+ \rightarrow p \overline p \pi ^+ $ signal yield, including the $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mode, $ B^+ \rightarrow p \overline p K ^+ $ cross-feed yield, signal efficiency, and relative systematic uncertainty in bins of $p\overline p $ invariant mass.	Table_2.pdf [47 KiB] HiDef png [69 KiB] Thumbnail [32 KiB] tex code
Yields, efficiencies and relative systematic uncertainties of the charmonium modes from the combined $(m_{p\overline p h^+},m_{p\overline p })$ fits for the regions $m_{p\overline p }\in[2.85,3.15] {\mathrm{ Ge V /}c^2} $ (for both $ B^+ \rightarrow p \overline p K ^+ $ and $ B^+ \rightarrow p \overline p \pi ^+ $ ) and $[3.60,3.75] {\mathrm{ Ge V /}c^2} $ (for $ B^+ \rightarrow p \overline p K ^+ $ ).	Table_3.pdf [46 KiB] HiDef png [54 KiB] Thumbnail [27 KiB] tex code
Fitted $ B^+ \rightarrow p \overline p K ^+ $ yields after subtracting the charmonium bands, efficiencies and relative systematic uncertainties in bins of $Kp$ invariant mass squared.	Table_4.pdf [46 KiB] HiDef png [68 KiB] Thumbnail [34 KiB] tex code
Fitted $ B^+ \rightarrow p \overline p K ^+ $ yields, efficiencies and relative systematic uncertainties in bins of $\cos\theta_{p}$.	Table_5.pdf [46 KiB] HiDef png [78 KiB] Thumbnail [20 KiB] tex code
Fitted $ B^+ \rightarrow p \overline p \pi ^+ $ signal yields, efficiencies and relative systematic uncertainties in bins of $\cos\theta_{p}$.	Table_6.pdf [46 KiB] HiDef png [75 KiB] Thumbnail [40 KiB] tex code
Systematic uncertainties for the $\mathcal{B}( B ^+ \rightarrow \overline{\Lambda} (1520)(\rightarrow K^+\overline p )p)/\mathcal{B}( B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} (\rightarrow p\overline p ) K ^+ )$ branching fraction ratio. The total uncertainty is the sum in quadrature of the individual sources.	Table_7.pdf [24 KiB] HiDef png [53 KiB] Thumbnail [23 KiB] tex code