A complete basis of helicity operators for subleading factorization

Abstract

Factorization theorems underly our ability to make predictions for many processes involving the strong interaction. Although typically formulated at leading power, the study of factorization at subleading power is of interest both for improving the precision of calculations, as well as for understanding the all orders structure of QCD. We use the SCET helicity operator formalism to construct a complete power suppressed basis of hard scattering operators for e + e − → dijets, e − p → e − jet, and constrained Drell-Yan, including the first two subleading orders in the amplitude level power expansion. We analyze the field content of the jet and soft function contributions to the power suppressed cross section for e + e − → dijet event shapes, and give results for the lowest order matching to the contributing operators. These results will be useful for studies of power corrections both in fixed order and resummed perturbation theory.

A subleading operator basis and matching for gg → H

“…We then perform the tree level matching onto our operators. These results can be used to study subleading power corrections either in fixed order, or resummed perturbation theory, and compliment our recent analysis for the case of qq initiated production [17].…”

“…[51,52], and more detailed discussions on the use of helicity operators can be found in refs. [17][18][19].…”

“…SCET has been used to study power corrections at the level of the amplitude [6] and to derive factorization theorems at subleading power for B decays [7][8][9][10][11][12][13]. More recently, progress has been made towards understanding subleading power corrections for event shape observables [14][15][16][17].…”

“…We present a complete operator basis to O(λ 2 ) in the SCET power expansion using operators of definite helicity [17][18][19], and discuss how helicity selection rules simplify the structure of the basis. We also classify all operators which can contribute at the cross section level at O(λ 2 ), and discuss the structure of interference terms between different operators in the squared matrix element.…”

Next-to-leading-logarithmic power corrections for N -jettiness subtraction in color-singlet production

“…One approach is to analytically calculate the power corrections to the SCET factorization theorem used in the below-cut region. The study of the structure of subleading power corrections to effectivetheory factorization theorems is also of general interest, and has received significant attention recently [21][22][23][24][25][26][27][28][29].…”