Pion-induced Drell-Yan processes within TMD factorization

Alexey Vladimirov

doi:10.1007/jhep10(2019)090

Abstract

We extract the pion transverse momentum dependent (TMD) parton distribu- tion by fitting the pion-induced Drell-Yan process within the framework of TMD factoriza- tion. The analysis is done at the next-to-next-to-leading order (NNLO) with proton TMD distribution and non-perturbative TMD evolution extracted earlier in the global fit. We observe the significant difference in the normalization of transverse momentum differential cross-section measured by E615 experiment and the theory prediction.

Highlights

The numerical part of the work has been done by artemide package [17, 18]
The pion transverse momentum dependent parton distribution function (TMDPDF) obtained in this work together with distribution of 100 replicas is available in the artemide-repository [17, 18] as Vpion19 TMDPDF set
The pion-induced Drell-Yan process has been studied, with the main aim to extract the values of pion unpolarized transverse momentum dependent parton distribution function (TMDPDF)

Summary

Theoretical framework

The derivation of the cross-section for Drell-Yan process in the TMD factorization has been a subject of many studies, see e.g. refs. [5,6,7, 16]. The non-perturbative expression for DNP has been extracted in [1] together with proton TMDPDF The deviation of ζNP from its exact values at large-b could be seen as a part of non-perturbative model It adds an undesired correlation between TMDPDFs and DNP at large-b. [1] was the absence of a way to find exact ζNP at large b, where the saddle point runs to μ < ΛQCD region This problem has been solved recently by using the DNP as an independent variable that accumulates all non-perturbative information and b-dependence. In this case, expression for exact ζNP can be found order-by-order in as which is the only parameter. The computation is done at complete NNLO perturbative accuracy

Comparison to the data

Conclusion

A Special null-evolution line at large b