Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/9710247

The Quark Spin Distributions of the Nucleon

Bo-Qiang Ma·Ivan Schmidt·Jacques Soffer
View original source ↗Read source document ↗Export metadata ↓

Abstract

The quark helicity measured in polarized deep inelastic scattering is different from the quark spin in the rest frame of the nucleon. We point out that the quark spin distributions $Δq_{RF}(x)$ are connected with the quark helicity distributions $Δq(x)$ and the quark transversity distributions $δq(x)$ by an approximate relation: $Δq_{RF}(x) + Δq(x)=2 δq(x)$. This relation will be useful in order to measure the rest frame (or quark model) spin distributions of the nucleon once the quark helicity distributions and quark transversity distributions are themselves measured. We also calculate the $x$-dependent quark transversity distributions $δq(x)$ and quark spin distributions $Δq_{RF}(x)$ in a light-cone SU(6) quark-spectator model, and present discussions on possible effect from the sea quark-antiquark pairs.

Explore related subjects

hep-phhep-exnucl-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bo-Qiang Ma, Ivan Schmidt, Jacques Soffer. 1998-09-16. The Quark Spin Distributions of the Nucleon. https://doi.org/10.1016/s0370-2693(98)01158-7

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

KEEP EXPLORING

Related papers

arXiv2026

Decoding Weak Phase Amplitudes in Charmed Baryon Decays

In this Letter, we present a strategy to decode decay amplitudes with different weak phases in two-body charmed baryon decays, addressing a long-standing challenge to understanding CP violation in this sector. Using SU(3) flavor symmetry, we disentangle the amplitudes defined through $M=λ_s A_s + λ_b A_b$ ($λ_i = V_{ui}V_{ci}^*$), enabling a data-driven determination of their relative hierarchy across Cabibbo-favored, singly, and doubly Cabibbo-suppressed modes. Applying this framework to current data, we find that the ratio $A_b/A_s$ is approximately 100 times larger than expectation of $\mathcal{O}(1)$ at $2.1σ$ level. This unexpected pattern may be accommodated by SU(3) breaking effects, but it can also point to new physics. We further show that the Lee-Yang parameters provide an independent and complementary probe. To resolve this ambiguity in the origin of the enhancement, we propose a decisive discriminator using decay modes insensitive to large SU(3) breaking, in particular $Ξ_c^0 \to pK^-$ and $Ξ_c^0 \to Σ^+π^-$ as golden channels. Measurements of these modes will distinguish between symmetry breaking effects and new physics, establishing a clean pathway to probe CP violation in the charm baryon sector.

hep-ph↗
arXiv2026

Next-to-next-to-next-to-leading order QCD corrections to photon-pair production

The production of two isolated photons at the Large Hadron Collider has applications in Higgs-boson phenomenology and in new-physics searches. In fact, measurements would provide more insight if a percent-level theoretical prediction were available. We account for next-to-next-to-next-to-leading order strong-interaction effects in the cross section for the first time. This is not only necessary to demonstrate the convergence of perturbation theory, but also results in a reduction of the theoretical uncertainty by a factor of three down to 3\%. With this, we pave the way to improved analyses.

hep-ph↗
arXiv2026

Charmonium production at SPS and FAIR energies

In this study we apply the Remler formalism to charmonium production at SPS and GSI/FAIR energies in order to investigate the effects of baryon-rich matter on charmonium production and dissociation in heavy-ion collisions within the Parton-Hadron-String Dynamics (PHSD). As a first step the Remler formalism is tested in p+p collisions and then applied to p+A collisions in order to extract the nuclear absorption cross section of charmonium, which is then utilized in heavy-ion collisions. We find that the Remler formalism successfully describes charmonium production in heavy-ion collisions at SPS energies when an in-medium heavy quark potential is implemented, in which $J/ψ$ dissociates near $T_c$. Finally the same formalism is applied to the low CERN/SPS energy and GSI/FAIR energies, where we estimate charmonium production.

hep-ph↗