cern.ch

Search for structure in the $B_s^0\pi^\pm$ invariant mass spectrum

[to restricted-access page]

Abstract

The $B_s^0\pi^\pm$ invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector corresponding to $3$ fb$^{-1}$ of $pp$ collision data at $\sqrt{s} = 7$ and $8$ TeV. No significant excess is found, and upper limits are set on the production rate of the claimed $X(5568)$ state within the LHCb acceptance. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the $B_s^0\pi^\pm$ final state. The same limits also apply to a possible exotic meson decaying through the chain $B_s^{*0}\pi^\pm$, $B_s^{*0} \to B_s^0 \gamma$ where the photon is excluded from the reconstructed decays.

Figures and captions

Selected candidates for (left) $ B ^0_ s \rightarrow D ^-_ s \pi ^+ $ and (right) $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi$ decays, with $ p_{\mathrm{ T}} ( B ^0_ s ) > 5 \mathrm{\,GeV} $, where the $ B ^0_ s $ signal window requirements of $|m( D ^-_ s \pi ^+ ) - 5367 \mathrm{\,MeV} | < 30 \mathrm{\,MeV} $ and $|m( { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi) - 5367 \mathrm{\,MeV} | < 13 \mathrm{\,MeV} $ are indicated by dotted lines. Results of the fits described in the text are superimposed with the total fit result shown as a red line, the signal component as an unfilled area, the combinatorial background component as a dark blue area and additional background contributions as a light green area.

Fig1a.pdf [35 KiB]
HiDef png [181 KiB]
Thumbnail [61 KiB]
*.C file
Fig1a.pdf
Fig1b.pdf [35 KiB]
HiDef png [177 KiB]
Thumbnail [57 KiB] *.C file
Fig1b.pdf

Results of the fit to the $ B ^0_ s \pi ^\pm $ mass distribution for candidates (both $ B ^0_ s $ modes combined) with minimum $ p_{\mathrm{ T}} ( B ^0_ s )$ of (top) $5 \mathrm{\,GeV} $, (middle) $10 \mathrm{\,GeV} $ and (bottom) $15 \mathrm{\,GeV} $. The component for the claimed $X(5568)$ state is included in the fit but is not significant. The distributions of the normalised residuals, or "pulls", displayed underneath the main figures show good agreement between the fit functions and the data.

Fig2a.pdf [47 KiB]
HiDef png [316 KiB]
Thumbnail [87 KiB]
*.C file
Fig2a.pdf
Fig2b.pdf [46 KiB]
HiDef png [315 KiB]
Thumbnail [90 KiB] *.C file
Fig2b.pdf
Fig2c.pdf [46 KiB]
HiDef png [332 KiB]
Thumbnail [101 KiB] *.C file
Fig2c.pdf

Upper limits (ULs) at 90 % confidence level (CL) as functions of the mass and width of a purported exotic state $X$ decaying to $ B ^0_ s \pi ^\pm $ with minimum $ p_{\mathrm{ T}} ( B ^0_ s )$ of (top) $5 \mathrm{\,GeV} $, (middle) $10 \mathrm{\,GeV} $ and (bottom) $15 \mathrm{\,GeV} $. The same limits also apply to a possible exotic meson decaying through the chain $ B ^{*0}_ s \pi ^\pm $, $ B ^{*0}_ s \rightarrow B ^0_ s \gamma$ where the photon is excluded from the reconstructed decays. In the latter case the nominal mass difference $m( B ^{*0}_ s ) - m( B ^0_ s ) = 48.6^{+1.8}_{-1.6} \mathrm{\,MeV} $ [16] has to be added to the values on the x-axis to get the mass of the exotic meson under investigation.

Fig3a.pdf [19 KiB]
HiDef png [240 KiB]
Thumbnail [75 KiB]
*.C file
Fig3a.pdf
Fig3b.pdf [19 KiB]
HiDef png [239 KiB]
Thumbnail [76 KiB] *.C file
Fig3b.pdf
Fig3c.pdf [19 KiB]
HiDef png [249 KiB]
Thumbnail [79 KiB] *.C file
Fig3c.pdf

Animated gif made out of all figures.

PAPER-2016-029.gif
Thumbnail
thumbnail_PAPER-2016-029.gif

Tables and captions

Yields, $N$, of $ B ^0_ s $ and $X(5568)$ candidates obtained from the fits to the $ B ^0_ s $ and $ B ^0_ s \pi ^\pm $ candidate mass distributions, with statistical uncertainties only. The values reported for $N( B ^0_ s )$ are those inside the $ B ^0_ s $ signal window. The reported values for $X(5568)$ are obtained from fits with signal mass and width parameters fixed to those determined by the D0 collaboration. Relative efficiencies $\epsilon^{\rm rel}(X)$ of the $ B ^0_ s $ and $X(5568)$ candidate selection criteria are also given. The reported uncertainties on the relative efficiencies are only statistical, due to the finite size of the simulated samples.

Table_1.pdf [53 KiB]
HiDef png [88 KiB]
Thumbnail [13 KiB]
tex code
Table_1.pdf

Supplementary Material [file]

Supplementary material full pdf

supple[..].pdf [230 KiB]
supplementary.pdf

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2016-029. The files are: Supplementary.pdf : An overview of the extra figures *.pdf, *.png, *.eps : The figures in variuous formats

Fig1a.pdf [44 KiB]
HiDef png [307 KiB]
Thumbnail [84 KiB]
*C file
Fig1a.pdf
Fig1b.pdf [43 KiB]
HiDef png [305 KiB]
Thumbnail [88 KiB]
*C file
Fig1b.pdf
Fig1c.pdf [43 KiB]
HiDef png [323 KiB]
Thumbnail [98 KiB]
*C file
Fig1c.pdf
Fig2.pdf [39 KiB]
HiDef png [270 KiB]
Thumbnail [83 KiB]
*C file
Fig2.pdf

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