Possible violation of sum rules for higher-twist parton distributions

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.52.3841· OSTI ID:249520

Burkardt, M ^[1]

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1. Institute for Nuclear Theory, University of Washington, Box 351550, Seattle, Washington 98195-1550 (United States)

Precise measurements of polarized electroproduction and Drell-Yan processes in the deep inelastic limit will soon provide the first information on the higher-twist parton distributions {ital g}{sub {ital T}}({ital x}) and {ital h}{sub {ital L}}({ital x}). Sum rules for higher-twist structure functions are only valid provided the corresponding Compton amplitudes satisfy unsubtracted dispersion relations. Subtracted dispersion relations have to be used when the (real part of the) forward scattering amplitudes do not fall off rapidly enough for {nu}{r_arrow}{infinity} (fixed {ital Q}{sup 2}). Formally, such subtractions lead to {delta} functions at the origin in the parton distributions, which are not accessible to experiment, and the integral over the data fails to satisfy the sum rule. The {delta} functions in the parton distributions can be identified with the zero modes that appear in light-front quantization. An explicit {ital infinite} {ital momentum} {ital boost} identifies these soft quark modes with low momentum contributions arising from self-energy-type interactions.

• OSTI ID: 249520
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 7 Vol. 52; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COMPTON EFFECT
DEEP INELASTIC SCATTERING
DISPERSION RELATIONS
DISTRIBUTION
DRELL MODEL
ELECTROPRODUCTION
PARTONS
QUANTIZATION
SCATTERING AMPLITUDES
SELF-ENERGY
STRUCTURE FUNCTIONS
SUM RULES
VIOLATIONS