Producing Fully-Charmed Tetraquarks via Charm Quark Fragmentation in Colliders

Within the framework of nonrelativistic QCD (NRQCD), we calculate the fragmentation function for a charm quark into an $S$-wave fully-charmed tetraquark, denoted as $T_{4c}$. The charm-to-$T_{4c}$ fragmentation function can be expressed as a sum of products of the perturbatively calculable short-distance coefficients and the nonperturbative long-distance matrix elements. The short-distance coefficients are ascertained through the perturbative matching procedure at lowest order in $\alpha_{s}$ and $v$ expansion. Incorporating the celebrated QCD factorization and the charm-to-$T_{4c}$ fragmentation function, we are able to predict the $T_{4c}$ production rate at high transverse momentum $p_T$ in colliders. In phenomenology, we approximate the NRQCD matrix elements with phenomenological four-body wave functions at the origin. After applying appropriate kinematic constraints, both the differential distribution over $p_T$ and the integrated cross sections are predicted at the \texttt{LHC}. The cross section can reach approximately $100$ fb, indicating the potential for a significant number of $T_{4c}$ events to be produced at the \texttt{LHC}. Additionally, we provide predictions for the photoproduction of $T_{4c}$ in electron-proton ($ep$) collisions. However, it is observed that the cross sections for these processes are relatively small at the \texttt{HERA}, \texttt{EIC} as well as \texttt{EicC}. Given these findings, the prospect of detecting these fully heavy tetraquarks at $ep$ colliders appears to be rather challenging.
Comment: 17 pages, 2 figures, 5 tables