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arXiv · 1405.1044

The Gluon Beam Function at Two Loops

Jonathan Gaunt·Maximilian Stahlhofen·Frank J. Tackmann
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Abstract

The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N-jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear ISR effects to the N-jettiness event shape through N^3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N^3LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.

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Jonathan Gaunt, Maximilian Stahlhofen, Frank J. Tackmann. 2014-05-05. The Gluon Beam Function at Two Loops. https://doi.org/10.1007/jhep08(2014)020

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