Forward χc production in pp and pA collisions within the CGC+NRQCD framework
Abstract
We study the forward χcJ production in the low p⊥ region in proton-proton (pp) and proton-nucleus (pA) collisions at the LHC within the framework of non-relativistic QCD (NRQCD) factorization and the Color Glass Condensate (CGC) effective field theory. Incorporating the small-x gluonic evolution via the running-coupling Balitsky-Kovchegov equation with various initial conditions, we systematically analyze the cross section ratio Rχc=σχc2/σχc1, and find that the theoretical predictions weakly depend on these inputs. Our predictions align well with the LHCb measurements for pPb collisions, however, overshoot those for pp collisions. We further investigate the feed down fractions Fχc1,2→ J/ψ=σχc1,2→ J/ψ/σJ/ψ. We notice that with the experimental measurement of prompt J/ψ cross section as inputs in the denominator the CGC+NRQCD predictions broadly match the data when choosing the standard McLerran-Venugopalan initial conditions. In contrast, implementing purely theoretical CGC+NRQCD predictions for both J/ψ and χc production yield systematic discrepancies across all tested parameters. This highlights a persistent challenge in achieving a simultaneous, unified description of χc and prompt J/ψ production within the current framework.
Related
- Investigating forward-backward asymmetry in D-meson production and anisotropic flow in p-Pb collisions at the LHC
- CGC Fit to HERA DIS and Forward Hadron Production in p+p Collisions
- Multiplicity-dependent forward jet production in proton–nucleus collisions
- Exclusive dimuon production and coherent charmonium photoproduction at forward rapidity in ultra-peripheral Pb–Pb collisions at √(sNN)=5.36 TeV
- Exclusive production of π+ π- pairs in diffractive γp and in pp collisions within the tensor-pomeron approach
BibTeX
@misc{he2026forward,
title = {{Forward $χ_c$ production in $pp$ and $pA$ collisions within the CGC+NRQCD framework}},
author = {Zhi-Guo He and Hao-yu Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24527},
eprint = {2610.24527},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24527},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Forward χ_c production in pp and pA collisions within the CGC+NRQCD framework
AU - Zhi-Guo He
AU - Hao-yu Liu
PY - 2026
DA - 2026/10/17
PB - arXiv
DO - 10.48550/arxiv.2610.24527
UR - https://arxiv.org/abs/2610.24527
AB - We study the forward χ_cJ production in the low p_⊥ region in proton-proton (pp) and proton-nucleus (pA) collisions at the LHC within the framework of non-relativistic QCD (NRQCD) factorization and the Color Glass Condensate (CGC) effective field theory. Incorporating the small-x gluonic evolution via the running-coupling Balitsky-Kovchegov equation with various initial conditions, we systematically analyze the cross section ratio R_χ_c=σ_χ_c2/σ_χ_c1, and find that the theoretical predictions weakly depend on these inputs. Our predictions align well with the LHCb measurements for pPb collisions, however, overshoot those for pp collisions. We further investigate the feed down fractions F_χ_c1,2→ J/ψ=σ_χ_c1,2→ J/ψ/σ_J/ψ. We notice that with the experimental measurement of prompt J/ψ cross section as inputs in the denominator the CGC+NRQCD predictions broadly match the data when choosing the standard McLerran-Venugopalan initial conditions. In contrast, implementing purely theoretical CGC+NRQCD predictions for both J/ψ and χ_c production yield systematic discrepancies across all tested parameters. This highlights a persistent challenge in achieving a simultaneous, unified description of χ_c and prompt J/ψ production within the current framework.
ER -