Comment on ‘‘Proton Spin Structure fromMeasurable
نویسندگان
چکیده
M q ðxÞ 1⁄4 x T q ðxÞ x T q ðxÞ: (5) Since Jþi is a leading-twist operator, it is clear that such a simple partonic interpretation should exist. However, Ji, Xiong, and Yuan misleadingly interpret Jþi as the transverse angular momentum operator. Indeed, in light-front quantization, the role of time is taken by xþ, so that Jþi is the light-front transverse boost operator. In terms of the more conventional instant-form boost (K) and rotation (J) operators (see, e.g., Refs. [6–8]), the light-front transverse boost operators read
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