Speaker
Description
Quarkonium production is considered one of the golden probes of quark-gluon plasma (QGP) formation in heavy-ion collisions. Quarkonium production in small collision systems is also important for investigating production mechanisms and providing a reference for heavy-ion collisions. Charmonium, a bound state of charm and anti-charm quark pairs, has its production mechanism described by perturbative QCD for heavy quark production and non-perturbative QCD calculations for the formation of the bound state. Measurements of J/$\psi$ and $\psi$(2S) cross sections in pp collisions are crucial for studying charmonium production mechanisms and testing different QCD-based model calculations. Especially, $\psi$(2S) production relative to J/$\psi$ provides strong discriminating power among quarkonium production models. Thanks to the ALICE online single-electron triggers from the Transition Radiation Detector (TRD), the $\psi$(2S) signal can be extracted at midrapidity via the dielectron decay channel.
In this contribution, the results on $p_{\mathrm T}$-differential $\psi$(2S) production cross section at midrapidity with the TRD-triggered data measured in ALICE in pp collisions at $\sqrt{s} = 13$ TeV will be shown for the first time, along with those for J/$\psi$. In addition, the excited-to-ground state yield ratio ($\psi$(2S)-to-J/$\psi$) at midrapidity will be discussed. Results will be compared to measurements at forward rapidity and available model calculations.
| Category | Experiment |
|---|---|
| Collaboration | ALICE |
