The semi-inclusive jet function in SCET and small radius resummation for inclusive jet production

By Zhong-Bo Kang, F. Ringer, I. Vitev. 2016

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A bstractWe introduce a new kind of jet function: the semi-inclusive jet function Ji(z, ωJ, μ), which describes how a parton i is transformed into a jet with a jet radius R and energy fraction z = ωJ/ω, with ωJ and ω being the large light-cone momentum component of the jet and the corresponding parton i that initiates the jet, respectively. Within the framework of Soft Collinear Effective Theory (SCET) we calculate both Jq (z, ωJ, μ) and Jg (z, ωJ, μ) to the next-to-leading order (NLO) for cone and anti-kT algorithms. We demonstrate that the renormalization group (RG) equations for Ji(z, ωJ, μ) follow exactly the usual DGLAP evolution, which can be used to perform the ln R resummation for inclusive jet cross sections with a small jet radius R. We clarify the difference between our RG equations for Ji(z, ωJ, μ) and those for the so-called unmeasured jet functions Ji(ωJ, μ), widely used in SCET for exclusive jet production. Finally, we present applications of the new semi-inclusive jet functions to inclusive jet production in e+e− and pp collisions. We demonstrate that single inclusive jet production in these collisions shares the same short-distance hard functions as single inclusive hadron production, with only the fragmentation functions Dih(z, μ) replaced by Ji(z, ωJ, μ). This can facilitate more efficient higher-order analytical computations of jet cross sections. We further match our ln R resummation at both LLR and NLLR to fixed NLO results and present the phenomenological implications for single inclusive jet production at the LHC.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/56dab0d52433d73449e79fac639c0b344c426fdc