One-loop angularity distributions with recoil using Soft-Collinear Effective Theory

Ankita Budhraja, Ambar Jain, Massimiliano Procura

Angularities are event shapes whose sensitivity to the splitting angle of a collinear emission is controlled by a continuous parameter b, with -1 <b <infinity. When measured with respect to the thrust axis, this class of QCD observables includes thrust (b = 1) and jet broadening (b = 0), the former being insensitive to the recoil of soft against collinear radiation, while the latter being maximally sensitive to it. Presently available analytic results for angularity distributions with b not equal 0 can be applied only close to the thrust limit since recoil effects have so far been neglected. As a first step to establish a comprehensive theoretical framework based on Soft-Collinear Effective Theory valid for all recoil-sensitive angularities, we compute for the first time angularity distributions at one-loop order in alpha(s) for all values of b taking into account recoil effects. In the differential cross section, these amount to novel sub-leading singular contributions and/or power corrections, where the former are characterized by fractional powers of the angularity and contribute appreciably close to the peak region, also for b greater than or similar to 0.5. Our calculations are checked against various limits known in the literature and agree with the numerical output of the Event2 generator.

Particle Physics
External organisation(s)
Indian Institute of Science, European Organization for Nuclear Research (CERN)
Journal of High Energy Physics
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103012 High energy physics
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