Production of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>X</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mn>3872</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math> at high multiplicity
Eric Braaten, Li-Ping He, Kevin Ingles, Jun Jiang
Abstract
The dependence of the production of the $X(3872)$ meson on the hadron multiplicity in $pp$ collisions has been used as evidence against $X$ being a charm-meson molecule. The argument is based in part on the incorrect assumption that the cross section for the breakup of $X$ by scattering with comovers can be approximated by a geometric cross section inversely proportional to the binding energy of $X$. The breakup cross section should instead be approximated by the probability-weighted sum of the cross sections for the scattering of comoving pions from the charm-meson constituents of $X$, which is insensitive to the binding energy. A simple modification of the comover interaction model gives excellent fits to the data from the LHCb Collaboration on the multiplicity dependence of the production of $X$ and $\ensuremath{\psi}(2S)$ using parameters compatible with $X$ being a loosely bound charm-meson molecule.