Phenomenology of IR-renormalons in inclusive processes

Measurements of QCD observables have reached such high precision that power corrections to the structure functions can often be extracted with a reasonable accuracy from the existing data. The situation on the theoretical side is much less clear. In the best understood case of deep inelastic scattering, the relevant contributions can be attributed in the framework of operator product expansion (OPE) to matrix elements of higher-twist operators [1], but their determination in QCD is ambiguous due to occurrence of power divergences [2]. From the phenomenological point of view, however, attempts to compute these matrix elements using e.g., QCD sum rules have provided results which seem to have at least the right order of magnitude [3] as compared with available experimental estimates.