Positivity constraints and flavor dependence of higher twists

Positivity constraints and flavor dependence of higher twists

The positivity bound for the transverse asymmetry A 2 may be improved and applied for each quark flavor separately. We use it to test the consistency of twist-two approximation for the transverse spin-dependent ( g T) and the longitudinal spin-averaged ( F L) structure functions. While it is satisfi...

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Bibliographic Details
Published in:Physics letters. B Vol. 490; no. 1; pp. 106 - 110
Main Authors: Soffer, J, Teryaev, O.V
Format: Journal Article
Language:English
Published: Elsevier B.V 28-09-2000
Subjects:
13.88.+e
12.38.Bx
Online Access:Get full text
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Summary:The positivity bound for the transverse asymmetry A 2 may be improved and applied for each quark flavor separately. We use it to test the consistency of twist-two approximation for the transverse spin-dependent ( g T) and the longitudinal spin-averaged ( F L) structure functions. While it is satisfied in the case of u quarks, it might be violated for d quarks in a region of moderate x because of its negative polarization. We attribute this inconsistency to a stronger twist-three contribution, whose existence found by the QCD sum rule method is a long-standing puzzle.
ISSN:0370-2693
1873-2445
DOI:10.1016/S0370-2693(00)00972-2