cern.ch

Observation of two resonances in the $\Lambda_b^0 \pi^\pm$ systems and precise measurement of $\Sigma_b^\pm$ and $\Sigma_b^{*\pm}$ properties

[to restricted-access page]

Information

Tools

Contact

Abstract

The first observation of two structures consistent with resonances in the final states $\Lambda_b^0 \pi^-$ and $\Lambda_b^0 \pi^+$ is reported using samples of $pp$ collision data collected by the LHCb experiment at $\sqrt{s} = 7$ and $8$ TeV, corresponding to an integrated luminosity of 3 $\mathrm{fb}^{-1}$. The ground states $\Sigma_b^\pm$ and $\Sigma_b^{*\pm}$ are also confirmed and their masses and widths are precisely measured.

Figures and captions

Mass distribution for the selected $\Lambda ^0_ b \rightarrow \Lambda ^+_ c \pi^-$ candidates. The points show experimental data.

Fig1.pdf [35 KiB]
HiDef png [178 KiB]
Thumbnail [66 KiB]
*.C file
Fig1.pdf

Mass distribution for selected $\Lambda ^0_ b \pi^\pm $ candidates. The points show experimental data. The left (right) column shows $\Lambda ^0_ b \pi^- $ ($\Lambda ^0_ b \pi^+ $) combinations. The top row shows the fits to the lower-mass states $\Sigma _b^\pm $ and $\Sigma _b^{*\pm} $. The lower row presents the fits to the new mass peaks with the requirement $ p_{\mathrm{ T}} (\pi_{s}^{\pm} )>1000$ $\mathrm{\,MeV}$ .

Fig2a.pdf [38 KiB]
HiDef png [189 KiB]
Thumbnail [74 KiB]
*.C file
Fig2a.pdf
Fig2b.pdf [37 KiB]
HiDef png [194 KiB]
Thumbnail [75 KiB] *.C file
Fig2b.pdf
Fig2c.pdf [38 KiB]
HiDef png [185 KiB]
Thumbnail [75 KiB] *.C file
Fig2c.pdf
Fig2d.pdf [38 KiB]
HiDef png [182 KiB]
Thumbnail [76 KiB] *.C file
Fig2d.pdf

Animated gif made out of all figures.

PAPER-2018-032.gif
Thumbnail
thumbnail_PAPER-2018-032.gif

Tables and captions

Summary of the results of the fits to the $ Q \equiv m(\Lambda ^0_ b \pi^\pm) - m(\Lambda ^0_ b ) - m(\pi^\pm)$ mass spectra. $Q_0$ and $\Gamma$ are the mean and the width of the Breit--Wigner function. The quoted uncertainties are statistical only.

Table_1.pdf [53 KiB]
HiDef png [76 KiB]
Thumbnail [13 KiB]
tex code
Table_1.pdf

Summary of the systematic uncertainties on the measured masses and widths. $Q_0$ and $\Gamma$ are the mean and the width of the Breit--Wigner function. All values are in $\mathrm{\,MeV}$ .

Table_2.pdf [48 KiB]
HiDef png [54 KiB]
Thumbnail [7 KiB]
tex code
Table_2.pdf

Masses and widths of the $\Sigma _b{(6097)}^\pm$ , $\Sigma _b^{*\pm}$ and $\Sigma _b^\pm$ baryons. Isospin splittings $\Delta({X^\pm}) = m(X^+) - m(X^-)$ and mass differences are also calculated. The first uncertainty is statistical, the second systematic. The systematic uncertainty on $m$ includes the uncertainty from the knowledge of the $\Lambda ^0_ b $ mass [41].

Table_3.pdf [54 KiB]
HiDef png [247 KiB]
Thumbnail [39 KiB]
tex code
Table_3.pdf

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