Virtual photon structure functions and positivity constraints

Abstract

We study the three positivity constraints among the eight virtual photon structure functions, derived from the Cauchy-Schwarz inequality and which are hence model-independent. The photon structure functions obtained from the simple parton model show quite different behaviors in a massive quark or a massless quark case, but they satisfy, in both cases, the three positivity constraints. We then discuss an inequality which holds among the unpolarized and polarized photon structure functions $F_1^{\gamma }$, $g_1^{\gamma }$ and $W_{TT}^{\tau }$, in the kinematic region ${\Lambda }^2\ll P^2\ll Q^2$, where $-Q^2(-P^2)$ is the mass squared of the probe (target) photon, and we examine whether this inequality is satisfied by the perturbative QCD results.

24 pages, 13 eps figures

References in corpus (5)

• Multi-Parton Amplitudes in Gauge Theories
• Spin-Dependent Structure Functions of Real and Virtual Photons
• Spin-Dependent Structure Functions of the Photon
• Polarized Virtual Photon Structure Function $g_2^{\gamma }$ and Twist-3 Effects in QCD
• Positivity constraints on photon structure functions

Cited by in corpus (7)

• Target Mass Corrections for the Virtual Photon Structure Functions to the Next-to-next-to-leading Order in QCD
• Top quark effects on the virtual photon structure function at ILC
• Heavy quark effects on parton distribution functions in the unpolarized virtual photon up to the next-to-leading order in QCD
• Resummation of large logarithms in the heavy quark effects on the parton distributions inside the virtual photon
• Photon Structure Function in Supersymmetric QCD Revisited
• The real photon structure functions in massive parton model in NLO
• Squark Contributions to Photon Structure Functions and Positivity Constraints