When semantics turns to substance : reformulating QCD analysis of F γ

When semantics turns to substance : reformulating QCD analysis of

0 QCD analysis of F γ 2 ( x , Q 2 ) : an unconventional view 1

Elements of the alternative approach to hard collisions of photons, proposed recently by the author, are reviewed, with particular attention to QCD analysis of F γ 2. This approach is based on clear separation of genuine QCD effects from those of pure QED origin and does not rely on the assumption that parton distribution functions of the photon behave as α/α s. It differs significantly from th...

The Virtual Photon Structure to the Next-to-next-to-leading Order in QCD

We investigate the unpolarized virtual photon structure functions F γ 2 (x,Q 2, P 2) and F γ L(x,Q 2, P 2) in perturbative QCD for the kinematical region Λ2 ≪ P 2 ≪ Q2, where −Q2(−P 2) is the mass squared of the probe (target) photon and Λ is the QCD scale parameter. Using the framework of the operator product expansion supplemented by the renormalization group method, we derive the definite pr...

Complete next-to-leading order QCD corrections to the photon structure functions F2 gamma (x,Q2) and FL gamma (x,Q2).

We present the complete NLO QCD analysis of the photon structure functions F γ 2 (x, Q 2) and F γ L (x, Q 2) for a real photon target. In particular we study the heavy flavor content of the structure functions which is due to two different production mechanisms, namely collisions of a virtual photon with a real photon, and with a parton. We observe that the charm contributions are noticeable fo...

QCD Sum Rule Calculation of γγ ∗ → π 0 Transition Form Factor

We develop a QCD sum rule analysis of the form factor F γ * γ * π • (q 2 , Q 2) in the region where virtuality of one of the spacelike photons is small q 2 ≪ 1 GeV 2 while another is large: Q 2 > ∼ 1 GeV 2. We construct the operator product expansion suitable for this kinematic situation and obtain a QCD sum rule for F γ * γ * π • (0, Q 2). Our results confirm expectation that the momentum tran...