# Observation for a new $B_s^0 \pi^\pm$ state

Abstract : We report the observation of a narrow structure, $X(5568)$, in the decay sequence $X(5568) \rightarrow B_s^0 \pi^{\pm}$, $B_s^0 \rightarrow J/\psi \phi$, $J/\psi\rightarrow \mu^+ \mu^-$, $\phi \rightarrow K^+K^-$. This is the first observation of a hadronic state with valence quarks of four different flavors. The mass and natural width of the new state are measured to be $m = 5567.8 \pm 2.9 {\rm \thinspace (stat)} ^{+0.9}_{-1.9} {\rm \thinspace (syst)}$ MeV/$c^2$ and $\Gamma = 21.9 \pm 6.4 {\rm \thinspace (stat)} ^{+5.0}_{-2.5} {\rm \thinspace (syst)}$ MeV/$c^2$, and the significance including look-elsewhere effect and systematic uncertainties is 5.1$\sigma$. The observation is based on$10.4~\rm{fb^{-1}}$ of $p \overline p$ collision data at $\sqrt{s}$ = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
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Submitted on : Thursday, February 25, 2016 - 7:12:45 AM
Last modification on : Tuesday, January 25, 2022 - 12:48:11 PM

### Citation

V.M. Abazov, U. Bassler, G. Bernardi, M. Besançon, D. Brown, et al.. Observation for a new $B_s^0 \pi^\pm$ state. Physical Review Letters, American Physical Society, 2016, 117, pp.022003. ⟨10.1103/PhysRevLett.117.022003⟩. ⟨in2p3-01278859⟩

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