Producing fully charm structures in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>J</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mi>ψ</mml:mi></mml:math>-pair invariant mass spectrum
Jun-Zhang Wang, Dian-Yong Chen, Xiang Liu, Takayuki Matsuki
Abstract
Focusing on the novel phenomenon of several enhancement structures existing in the invariant mass spectrum of a $J/\ensuremath{\psi}$ pair, which was reported by LHCb very recently, we find a new dynamical mechanism based on the special reactions, where all the possible combinations of a double charmonium directly produced by a proton-proton collision are transitioned into final-state $J/\ensuremath{\psi}J/\ensuremath{\psi}$. Under this framework, totally different from the popular tetraquark explanation, the LHCb experimental data of the line shape of the $J/\ensuremath{\psi}$-pair invariant mass spectrum can be well mimicked. Since the proposed dynamical mechanism is universal enough, we further predict the possible enhancement structures existing in the $\mathrm{\ensuremath{\Upsilon}}(1S)$-pair invariant mass spectrum, which may provide a realistic approach to test the new mechanism proposed in this work and form a new task for the LHCb and CMS experiments.