Off forward non-s-channel helicity conserving contributions to exclusive vector quarkonium production from the spin dependent BFKL Pomeron

Journal Article · Mon Aug 25 00:00:00 EDT 2025 · Physical Review D

DOI:https://doi.org/10.1103/7t3g-d4wr· OSTI ID:2584574

Benić, Sanjin ^[1]; Dumitru, Adrian ^[2]

---

1. University of Zagreb (Croatia)
2. Baruch College, New York, NY (United States); The City University of New York, NY (United States)

A novel contribution to off forward, exclusive vector quarkonium production, γ(*)+p → V+p, at high energy is derived which corresponds to a t-channel exchange of a Balitsky-Fadin-Kuraev-Lipatov (BFKL) hard Pomeron, with a helicity flip of the proton. This “spin-dependent BFKL Pomeron” is required in a consistent expansion in powers of the momentum transfer t ≈−Δ$$^{2}_{⊥}$$ beyond first order. The spin-dependent Pomeron violates s-channel helicity conservation at O(Δ$$^{2}_{⊥}$$), and beyond. Expanding to leading twist only, it corresponds to generalized parton distributions E_g(x,t) for vanishing skewness. We derive explicit expressions for the eikonal BFKL amplitudes, to all orders in dipole size times momentum transfer, for all helicity configurations of the particles in the initial and final states. We also provide numerical estimates of the helicity flip two gluon exchange amplitude at moderate x from a light cone quark model of the proton. The spin dependent BFKL Pomeron could, in principle, be discovered via double spin asymmetries in e+p → e+p+J/ψ with a transversely polarized proton and longitudinally polarized electron in the initial state.

• Research Organization: The City University of New York, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: SC0002307
• OSTI ID: 2584574
• Alternate ID(s): OSTI ID: 3024192
• Journal Information: Physical Review D, Journal Name: Physical Review D Journal Issue: 3 Vol. 112; ISSN 2470-0010; ISSN 2470-0029
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

Deep inelastic scattering
Diffractive production
Hadron production
Nucleon spin structure
Particle production
Perturbative QCD
QCD phenomenology
Quantum chromodynamics
Quarkonia
Scattering amplitudes