The nature of X(3872) from high-multiplicity pp collisions

The structure of exotic resonances that do not trivially fit the usual quark model expectations has been a matter of intense scientific debate during the last two decades. A possible way of estimating the size of these states is to study their behavior when immersed in QCD matter. Recently, LHCb has measured the relative abundance of the exotic X(3872)overtheordinaryψ(2S).Weusethecomover interaction model to study the yield of a compact X (3872). To confirm the reliability of the model in high-multiplicity pp collisions, we describe the suppression of excited over ground Υ states. With this at hand, we show that the size of the compact X(3872) would be slightly larger than that of the ψ(2S). If the X(3872) is instead assumed to be a meson molecule of large size, we argue that its evolution in QCD matter should be described via a coalescence model, as suggested by data on deuteron production. We show that the predictions of this model for the X (3872) are in contrast with data.