Wilson-line and color charge density correlators and the production ofη'in the color glass condensate forppand<

Abstract

We compute the inclusive differential cross section production of the pseudo-scalar meson η ′ in high-energy proton-proton (pp) and proton-nucleus (pA) collisions. We use an effective coupling between gluons and η ′ meson to derive a reduction formula that relates the η ′ production to a field-strength tensor correlator. For pA collisions we take into account saturation effects on the nucleus side by using the Color Glass Condensate formalism to evaluate this correlator. We derive new results for Wilson line -color charges correlators in the McLerran-Venugopalan model needed in the computation of η ′ production. The unintegrated parton distribution functions are used to characterize the gluon distribution inside protons. We show that in pp collisions, the cross section depends on the parametrization of unintegrated parton distribution functions and thus, it can be used to put constraints on these distributions. We also demonstrate that in pA collisions, the cross section is sensitive to saturation effects so it can be utilized to estimate the value of the saturation scale.

Gluon distribution functions and Higgs boson production at moderate transverse momentum

“…This indicates that the naive-k t factorization breaks down even for the color-neutral particle production in the dense medium in the hadronic scattering processes. Similar conclusion has also been drawn for the η ′ particle production in pA collisions in the saturation model calculations [17]. However, because of the large Higgs mass, we should be able to modify the naive-k t factorization to establish an effective k tfactorization for its production at low transverse momentum P ⊥ ≪ M, following the similar study in Ref.…”

“…This indicates that the naive k t -factorization breaks down even for the color-neutral particle production in the dense region in hadronic scattering processes as also found in Ref. [17], similar to the situation for the heavy quark-antiquark pair production process [18].…”

Initial correlations of the Glasma energy-momentum tensor

“…We name these 'connected' correlators, and indicate them as ... c . Based on the diagrammatic rules derived in [41] we are able to compute these contributions and express them in terms of the following function:…”

Memory effect in Yang-Mills theory

“…The same can be done here, too, on the amplitude level, but averaging over an ensemble would need computing very complicated correlators. The level of complication is set by a related computation of η production [30].…”

“…Also longitudinal fields are induced by the axion but we are so far unable to compute their effect. Longitudinal fields enter in the central region of nucleus-nucleus collisions [15,19,28] or in phenomenological analyses of η production [30].…”