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.
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{ Ge V} $, where the $ B ^0_ s $ signal window requirements of $m( D ^_ s \pi ^+ )  5367 \mathrm{ Me V}  < 30 \mathrm{ Me V} $ and $m( { J \mskip 3mu/\mskip 2mu\psi \mskip 2mu} \phi)  5367 \mathrm{ Me V}  < 13 \mathrm{ Me V} $ 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 [190 KiB] Thumbnail [169 KiB] *.C file 

Fig1b.pdf [35 KiB] HiDef png [184 KiB] Thumbnail [158 KiB] *.C file 

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{ Ge V} $, (middle) $10 \mathrm{ Ge V} $ and (bottom) $15 \mathrm{ Ge V} $. 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 [318 KiB] Thumbnail [257 KiB] *.C file 

Fig2b.pdf [46 KiB] HiDef png [317 KiB] Thumbnail [262 KiB] *.C file 

Fig2c.pdf [46 KiB] HiDef png [334 KiB] Thumbnail [284 KiB] *.C file 

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{ Ge V} $, (middle) $10 \mathrm{ Ge V} $ and (bottom) $15 \mathrm{ Ge V} $. 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{ Me V} $ [16] has to be added to the values on the xaxis to get the mass of the exotic meson under investigation. 
Fig3a.pdf [19 KiB] HiDef png [248 KiB] Thumbnail [205 KiB] *.C file 

Fig3b.pdf [19 KiB] HiDef png [248 KiB] Thumbnail [206 KiB] *.C file 

Fig3c.pdf [19 KiB] HiDef png [258 KiB] Thumbnail [214 KiB] *.C file 

Animated gif made out of all figures. 
PAPER2016029.gif Thumbnail 
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 [91 KiB] Thumbnail [44 KiB] tex code 
Supplementary material full pdf 
supple[..].pdf [230 KiB] 

This ZIP file contains supplemetary material for the publication LHCbPAPER2016029. 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 [309 KiB] Thumbnail [249 KiB] *C file 

Fig1b.pdf [43 KiB] HiDef png [307 KiB] Thumbnail [255 KiB] *C file 

Fig1c.pdf [43 KiB] HiDef png [326 KiB] Thumbnail [276 KiB] *C file 

Fig2.pdf [39 KiB] HiDef png [277 KiB] Thumbnail [224 KiB] *C file 
Created on 05 March 2021.