Abstract
We assess and compare different methods for including leading threshold logarithms at next-to-leading-power in prompt photon production at hadron colliders, for both the direct and parton fragmentation mechanisms. We do this in addition to next-to-leading logarithmic threshold and joint resummation at leading power. We study the size of these effects and their scale variations for LHC kinematics. We find that the next-to-leading power effects have a noticeable effect on the photon transverse momentum distribution, typically of order $\mathcal{O}(10\%)$, depending on the method of inclusion. Our results indicate that next-to-leading power terms can reduce the scale dependence of the distribution considerably.
Highlights
We consider the production of a prompt photon with a given transverse momentum pT in hadronic collisions
We study the size of these effects and their scale variations for Large Hadron Collider kinematics
The parameter μin the second line of (14) acts as a cut off on the recoil transverse momentum to avoid the singularity in the kinematic factor at pT 1⁄4 QT=2, where the assumption that QT is small compared to pT is not valid
Summary
We consider the production of a prompt photon with a given transverse momentum pT in hadronic collisions. In [17,18] it was shown, to NLL accuracy, that threshold logarithms can be resummed jointly with recoil corrections This joint resummation has been applied to direct prompt photon production in [19], heavy quark production in [20], BSM processes in [21,22,23], and to vector boson and Higgs production in [24,25]. Preliminary studies [67,68,69] were performed for the resummation of a large class of leading logarithmic (LL with m 1⁄4 2n − 1) NLP terms for direct production of prompt photons, in both threshold and joint resummation. II, while in Appendix B we compare the NLO expansion of our resummed expressions at NLP with exact results
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