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Theory Center Seminar<br>
Mon., April 11, 2016<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room L102<br>
<br>
Daria Zieminska<br>
Indiana University<br>
<br>
<b>Observation of a New $B_s</b><b><sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup></b><b>
\pi^{\pm}$ State</b><br>
<br>
We report the observation of a narrow structure, $X(5568)$, in the
decay sequence $X(5568) \rightarrow B_s<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup>
\pi^{\pm}$, <br>
$B_s<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup>
\rightarrow J/\psi \phi$, $J/\psi \rightarrow \mu^+ \mu^-$, $\phi
\rightarrow K^+K^-$. This is the first observation<br>
of a hadronic state with valence quarks of four different flavors.
The mass and natural width of the new state are measured to be <br>
$m = 5567.8 \pm 2.9 {\rm \thinspace (stat)} ^{+0.9}_{-1.9} {\rm
\thinspace (syst)}$ MeV/$c<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>2</sup>$
and $\Gamma = 21.9 \pm 6.4 <br>
{\rm \thinspace (stat)} ^{+5.0}_{-2.5} {\rm \thinspace (syst)} $
MeV/$c<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>2</sup>$,
and
the significance including look-elsewhere effect and <br>
systematic uncertainties is 5.1$\sigma$. The observation is based
on $10.4~\rm{fb^{-1}}$ of $p \overline p $ collision data at<br>
$\sqrt{s}$ = 1.96 TeV collected by the D0 experiment at the
Fermilab Tevatron collider. <br>
<br>
<br>
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