Renormalization of twist-four operators in QCD

Abstract

Abstract:Extending the work by Bukhvostov, Frolov, Lipatov and Kuraev (BFLK) on the renormalization of quasipartonic operators we derive a complete set of two-particle renormalization group kernels that enter QCD evolution equations to twist-four accuracy. It is shown that the 2 → 2 evolution kernels which involve "non-partonic" components of field operators, and, most remarkably, also 2 → 3 kernels do not require independent calculation and can be restored from the known results for quasipartonic operators using conformal symmetry and Lorentz transformations. The kernels are presented for the renormalization of light-ray operators built of chiral fields in a particular basis such that the conformal symmetry is manifest. The results can easily be recast in momentum space, in the form of evolution equations for generalized parton distributions.

Naive time-reversal odd phenomena in semi-inclusive deep-inelastic scattering from light-cone constituent quark models

“…The dashed curves show the results at the hadronic scale of the model, while the solid curves are obtained by applying LO evolution to Q 2 = 2.5 GeV 2 [77]. Since the exact evolution equations for the T-odd TMDs are still under study [78][79][80][81]83], we use those evolution equations which seem most promising to "simulate" the correct evolution.…”

Evolution Equations of Twist-Three Parton Distributions

“…The calculation was done using the two-particle kernels for the renormalization of light-ray operators, which are available from Ref. [14]. Evolution equations can be obtained for arbitrary parton momentum fractions, for the flavor-(non)singlet distributions, with both positive and negative C-parity.…”

“…[19] (see also [20,21,22]). Alternatively, the answer for H can be obtained by simple algebra from the known expressions for the one-loop two-particle BFLK kernels 12,14 . This technique is quite general and applicable to arbitrary twist-three (and twist-four 14 ) evolution equations.…”

“…The evolution equations for the particular parton distributions relevant for SSA can be obtained from the BFLK kernels by simple algebra. Using an updated version of this technique 13,14 we write down the complete evolution equations for all relevant three-particle correlation functions.…”

Finite-t and target mass corrections in off-forward hard reactions

“…Renormalization of twist-four non-quasipartonic operators was studied recently in [23,24]. The main result is that in a suitable operator basis the corresponding RG equations can be written in terms of several SL(2)-invariant kernels.…”