Hunting for Higher Twists — A Precaution

Abstract

One of the major obstacles in performing unambiguous phenomenological studies of QCD at short distances1 is the missing theoretical knowledge of the relative normalization of twist-two and higher twist contributions. Presently, this issue is studied mainly by fitting data with a twist-two component which is well known and adding to it a higher twist component, which apart from its leading Q2 and x dependence there is not much other theoretical input in it. As a result one finds in the literature a very wide range of opinions concerning the relevance of higher twist terms to presently available data2.