NRQCD analysis of charmonium production with pion and proton beams at fixed-target energies

Chia-Yu Hsieh , Yu-Shiang Lian , Wen-Chen Chang , Jen-Chieh Peng , Stephane Platchkov (1) , Takahiro Sawada

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers

We present an analysis of hadroproduction of $J∕\psi$ and $\psi \left(2S\right)$ at fixed-target energies in the framework of non-relativistic QCD (NRQCD). Using both pion- and proton-induced data, a new determination of the color-octet long-distance matrix elements (LDMEs) is obtained. Compared with previous results, the contributions from the $q\bar{q}$ and color-octet processes are significantly enhanced, especially at lower energies. A good agreement between the pion-induced $J∕\psi$ production data and NRQCD calculations using the newly obtained LDMEs is achieved. We find that the pion-induced charmonium production data are sensitive to the gluon density of pions, and favor pion PDFs with relatively large gluon contents at large $x$. •Fixed-target charmonium data are reasonably described by NRQCD.•A new determination of the color-octet long-distance matrix elements is obtained.•The pion-induced charmonium data differentiate the gluon density of pion PDFs.

Mots clés: Charmonium production; Pion PDFs; NRQCD; Color-octet matrix elements; Gluon; quantum chromodynamics: nonrelativistic; color: octet; charmonium: production; pi: structure function; gluon: density; quark antiquark; p: beam; pi: beam; J/psi(3100): hadroproduction; psi(3685): hadroproduction

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]

Chia-Yu Hsieh, Yu-Shiang Lian, Wen-Chen Chang, Jen-Chieh Peng, Stephane Platchkov, et al.. NRQCD analysis of charmonium production with pion and proton beams at fixed-target energies. Chin.J.Phys., 2021, 73, pp.1510. ⟨10.1016/j.cjph.2021.06.001⟩. ⟨hal-03191141⟩