Speaker
Description
The STAR collaboration has recently reported on the observation of a significant suppression of forward back-to-back hadron pairs produced in p-Au and p-Al collisions compared to p-p collisions [1]. The A-dependence of this suppression follows the expectations of the color glass condensate effective theory of high-energy QCD, thus giving evidence of the manifestation of gluon saturation at colliders. Comparisons of data with the results of our CGC-based calculations [2] have been also presented. However, such comparisons are at best qualitative due to the current lack of an appropriate implementation of the effect of initial- and final-state soft-gluon radiation (Sudakov resummation) in the cross section of forward production.
In this contribution, we extend our previous work [2] to compute the cross section of forward di-hadron and di-jet production in the CGC framework including Sudakov resummation effects with analytically-controlled methods [3]. We discuss the impact of the Sudakov resummation both in low-pt production at RHIC and high-pt production of di-jets, for which forward data is also available at the LHC [4]. We argue that the impact of soft-gluon radiation is in general better understood at high pt, and that its effect is that of pushing the RpA of forward di-jet production towards unity, thus taming the visibility of the suppression induced by gluon saturation. We identify, thus, hadrons in an intermediate pt range (5-10 GeV) as optimal probes where both genuine saturation signals are visible and Sudakov resummation effects are under control. Quantitative calculations based on the acceptance of the future FoCal upgrade of the ALICE detector are presented. We predict, in particular, that RpA for forward di-hadrons will be as low as 0.75 at Δϕ=π due to gluon saturation [5].
[1] STAR Collaboration, https://arxiv.org/pdf/2111.10396.pdf
[2] J. L. Albacete, G. Giacalone, C. Marquet and M. Matas, https://arxiv.org/abs/1805.05711
[3] A. Stasto, S-Y. Wei, B-W. Xiao, and F. Yuan, https://arxiv.org/abs/1805.05712
[4] ATLAS Collaboration, https://arxiv.org/abs/1901.10440
[5] G. Giacalone, C. Marquet, M. Matas, S-Y. Wei, in preparation
| Submitted on behalf of a Collaboration? | No |
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