Two-gluon correlations in heavy-light ion collisions: Energy and geometry dependence, IR divergences, and kT-factorization

Yuri V. Kovchegov, Douglas E. Wertepny

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

We study the properties of the cross section for two-gluon production in heavy-light ion collisions derived in our previous paper [1] in the saturation/Color Glass Condensate framework. Concentrating on the energy and geometry dependence of the corresponding correlation functions we find that the two-gluon correlator is a much slower function of the center-of-mass energy than the one- and two-gluon production cross sections. The geometry dependence of the correlation function leads to stronger azimuthal near- and away-side correlations in the tip-on-tip U + U collisions than in the side-on-side U + U collisions, an exactly opposite behavior from the correlations generated by the elliptic flow of the quark-gluon plasma: a study of azimuthal correlations in the U + U collisions may thus help to disentangle the two sources of correlations. We demonstrate that the cross section for two-gluon production in heavy-light ion collisions contains a power-law infrared (IR) divergence even for fixed produced gluon momenta: while saturation effects in the target regulate some of the power-law IR-divergent terms in the lowest-order expression for the two-gluon correlator, other power-law IR-divergent terms remain, possibly due to absence of saturation effects in the dilute projectile. Finally we rewrite our result for the two-gluon production cross-section in a k T-factorized form, obtaining a new factorized expression involving a convolution of one- and two-gluon Wigner distributions over both the transverse momenta and impact parameters. We show that the two-gluon production cross-section depends on two different types of unintegrated two-gluon Wigner distribution functions.

Original languageEnglish
Pages (from-to)254-295
Number of pages42
JournalNuclear Physics A
Volume925
DOIs
StatePublished - 1 Jan 2014
Externally publishedYes

Keywords

  • Color glass condensate
  • Gluon production
  • High energy collisions
  • Parton saturation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Fingerprint

Dive into the research topics of 'Two-gluon correlations in heavy-light ion collisions: Energy and geometry dependence, IR divergences, and kT-factorization'. Together they form a unique fingerprint.

Cite this