English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We study the distribution of gluons in transverse space in the nucleon atmoderately small x (~10^{-2}). At large transverse distances (impactparameters) the gluon density is generated by the 'pion cloud' of the nucleon,and can be calculated in terms of the gluon density in the pion. We investigatethe large-distance behavior in two different approaches to chiral dynamics: i)phenomenological soft-pion exchange, ii) the large-N_c picture of the nucleonas a classical soliton of the pion field, which corresponds to degenerate N andDelta states. The large-distance contributions from the 'pion cloud' cause a\~20% increase in the overall transverse size of the nucleon if x dropssignificantly below M_pi/M_N. This is in qualitative agreement with theobserved increase of the slope of the t-dependence of the J/psi photoproductioncross section at HERA compared to fixed-target energies. We argue that the gluein the pion cloud could be probed directly in hard electroproduction processesaccompanied by 'pion knockout', gamma^* + N -> gamma (or rho, J/psi) + pi + N',where the transverse momentum of the emitted pion is large while that of theoutgoing nucleon is restricted to values of order M_pi.Comment: 20 pages, revtex4, 10 eps figure

Chiral dynamics and the growth of the nucleon’s gluonic transverse size at smallx