The resummed differential thrust rate in $e^{+}{e}^{-}$ annihilation is calculated using soft-collinear effective theory (SCET). The resulting distribution in the two-jet region ($T\sim 1)$ is found to agree with the corresponding expression derived by the standard approach. A matching procedure to account for finite corrections at $T<1$ is then described. There are two important advantages of the SCET approach. First, SCET manifests a dynamical seesaw scale $q=p^2/Q$ in addition to the center-of-mass energy $Q$ and the jet mass scale $p\sim Q\sqrt{(1-T)}$. Thus, the resummation of logs of $p/q$ can be cleanly distinguished from the resummation of logs of $Q/p$. Second, finite parts of loop amplitudes appear in specific places in the perturbative distribution: in the matching to the hard function, at the scale $Q$, in matching to the jet function, at the scale $p$, and in matching to the soft function, at the scale $q$. This allows for a consistent merger of fixed order corrections and resummation. In particular, the total NLO $e^{+}{e}^{-}$ cross section is reproduced from these finite parts without having to perform additional infrared regulation.

• Received 28 September 2007

DOI:https://doi.org/10.1103/PhysRevD.77.014026