Search for a scalar partner of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mn>3872</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> via <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" displa

TL;DR: Researchers searched for a scalar partner of the X(3872) using 2.93 fb^-1 of data from the BESIII detector, observing no significant signals and setting upper limits on product branching fractions for the X(3700) at the 90% confidence level.

Abstract: Using a data sample corresponding to an integrated luminosity of $2.93\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, we search for a scalar partner of the $X(3872)$, denoted as $X(3700)$, via $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}}$ and $\ensuremath{\gamma}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ processes. No significant signals are observed and the upper limits of the product branching fractions $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}X(3700))\ifmmode\cdot\else\textperiodcentered\fi{}\mathcal{B}(X(3700)\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}})$ and $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}\ensuremath{\gamma}X(3700))\ifmmode\cdot\else\textperiodcentered\fi{}\mathcal{B}(X(3700)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi})$ are determined at the 90% confidence level, for the narrow $X(3700)$ with a mass ranging from 3710 to $3740\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, which are from 0.9 to $1.9(\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5})$ and 0.9 to $3.4(\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5})$, respectively.