Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/9903280

Chi_2 production in polarized pp collisions at RHIC: measuring ΔG and testing the color octet model

R. L. Jaffe·D. Kharzeev
View original source ↗Read source document ↗Export metadata ↓

Abstract

We consider the production and decay of the $χ_2$ charmonium state in polarized and unpolarized $pp$ collisions at RHIC in the framework of an effective theory based on the QCD multipole expansion. We find that the angular distribution in the decay of the produced charmonium, $χ_2 \to J/ψ+ γ$, in the unpolarized case allows us to distinguish clearly between the color singlet and color octet production mechanisms. Once the production mechanism is known, the angular distribution in the polarized case can be used to measure the polarized gluon distribution in the proton, $ΔG(x)$.

Explore related subjects

hep-phhep-exnucl-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

R. L. Jaffe, D. Kharzeev. 1999-03-08. Chi_2 production in polarized pp collisions at RHIC: measuring ΔG and testing the color octet model. https://doi.org/10.1016/s0370-2693(99)00448-7

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Precision tests of third-generation four-quark operators: $gg \to h$ and $h \to γγ$

We compute the two-loop contributions to Higgs production via gluon-gluon fusion ($gg \to h$) and Higgs decay into two photons ($h \to γγ$), arising from third-generation four-quark operators in the Standard Model effective field theory (SMEFT). Our analysis is performed in the broken phase of the theory, retaining the full dependence on the Higgs and heavy-quark masses. This includes both finite matching corrections and logarithmic effects stemming from the renormalization group evolution within the SMEFT. As a byproduct, two-loop anomalous dimensions in the SMEFT are obtained. We also briefly discuss the phenomenological implications of our two-loop calculations.

hep-ph↗
arXiv2026

Quantum Sensing Radiative Decays of Neutrinos and Dark Matter Particles

We explore a novel strategy for detecting the radiative decay of very weakly interacting particles by leveraging the extreme sensitivity of quantum devices, such as superconducting transmon qubits and trapped ion systems, to faint electromagnetic signals. By modeling the effective electric field induced by the decay photons, we evaluate the response of quantum sensors across two particle physics scenarios: the cosmic neutrino background and two-component dark matter. We assess the discovery potential of these devices and outline the parameter space accessible under current experimental capabilities. Our analysis demonstrates that quantum sensors can probe radiative decays of dark matter candidates using existing technology, while probing neutrino magnetic moments beyond current limits will require scalable quantum architectures with collective enhancement.

hep-ph↗
arXiv2026

The $\sin(2ϕ)$ azimuthal asymmetry in exclusive $π^0$ production

The $\sin(2ϕ)$ azimuthal angular correlation between the transverse momenta of the scattered electron and the recoil proton in the $ep\to e^\prime p^\prime π^0$ process provides a probe for quark orbital angular momentum. We numerically calculate this asymmetry for the future Electron-Ion Collider (EIC) in the U.S. and China (EicC) kinematics using a light-front quark-scalar-diquark model, in which the light-front wave functions are derived from the soft-wall AdS/QCD framework. We also investigate the properties of the valence quark angular momentum expressed in terms of helicity-independent and helicity-dependent parton distributions. This study aims to establish theoretical constraints on the asymmetry sensitive to the quark orbital angular momentum prior to its first experimental measurement..

hep-ph↗