## Abstract

We extend the QCD sum rule analysis of the F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1}, q{sup 2}{sub 2}) form factor into the region where one of the photons has small virtuality: |q{sup 2}{sub 1}| << |q{sup 2}{sub 2}| {>=} 1 GeV{sup 2}. In this kinematics one should perform an additional factorization of short- and long-distance contributions. The extra long distance sensitivity of the three-point amplitude is described by two-point correlators (bi locals), and the low-momentum dependence of the correlators involving composite operators of two lowest twists is extracted from auxiliary QCD sum rules. The sum rule obtained is regular in the limit q{sup 2}{sub 1} -> 0. Our estimates for F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1} = 0, Q{sup 2}{sub 2}) are in good agreement with existing experimental data. (author). 22 refs.; 3 figs.

Radyushkin, A V;

^{[1] }Ruskov, R^{[2] }- Joint Inst. for Nuclear Research, Dubna (Russian Federation). Lab. of Theoretical Physics
- Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika

## Citation Formats

Radyushkin, A V, and Ruskov, R.
Form Factor of the Process {gamma}{sup *}{gamma}{sup *} -> {pi} {sup 0} for Small Virtuality of One of the Photons and QCD Sum Rules (2): Sum Rule.
JINR: N. p.,
1994.
Web.

Radyushkin, A V, & Ruskov, R.
Form Factor of the Process {gamma}{sup *}{gamma}{sup *} -> {pi} {sup 0} for Small Virtuality of One of the Photons and QCD Sum Rules (2): Sum Rule.
JINR.

Radyushkin, A V, and Ruskov, R.
1994.
"Form Factor of the Process {gamma}{sup *}{gamma}{sup *} -> {pi} {sup 0} for Small Virtuality of One of the Photons and QCD Sum Rules (2): Sum Rule."
JINR.

@misc{etde_10112560,

title = {Form Factor of the Process {gamma}{sup *}{gamma}{sup *} -> {pi} {sup 0} for Small Virtuality of One of the Photons and QCD Sum Rules (2): Sum Rule}

author = {Radyushkin, A V, and Ruskov, R}

abstractNote = {We extend the QCD sum rule analysis of the F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1}, q{sup 2}{sub 2}) form factor into the region where one of the photons has small virtuality: |q{sup 2}{sub 1}| << |q{sup 2}{sub 2}| {>=} 1 GeV{sup 2}. In this kinematics one should perform an additional factorization of short- and long-distance contributions. The extra long distance sensitivity of the three-point amplitude is described by two-point correlators (bi locals), and the low-momentum dependence of the correlators involving composite operators of two lowest twists is extracted from auxiliary QCD sum rules. The sum rule obtained is regular in the limit q{sup 2}{sub 1} -> 0. Our estimates for F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1} = 0, Q{sup 2}{sub 2}) are in good agreement with existing experimental data. (author). 22 refs.; 3 figs.}

place = {JINR}

year = {1994}

month = {Dec}

}

title = {Form Factor of the Process {gamma}{sup *}{gamma}{sup *} -> {pi} {sup 0} for Small Virtuality of One of the Photons and QCD Sum Rules (2): Sum Rule}

author = {Radyushkin, A V, and Ruskov, R}

abstractNote = {We extend the QCD sum rule analysis of the F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1}, q{sup 2}{sub 2}) form factor into the region where one of the photons has small virtuality: |q{sup 2}{sub 1}| << |q{sup 2}{sub 2}| {>=} 1 GeV{sup 2}. In this kinematics one should perform an additional factorization of short- and long-distance contributions. The extra long distance sensitivity of the three-point amplitude is described by two-point correlators (bi locals), and the low-momentum dependence of the correlators involving composite operators of two lowest twists is extracted from auxiliary QCD sum rules. The sum rule obtained is regular in the limit q{sup 2}{sub 1} -> 0. Our estimates for F{sub {gamma}}{sup *}{sub {gamma}}{sup *} -> {pi}{sup 0} (q{sup 2}{sub 1} = 0, Q{sup 2}{sub 2}) are in good agreement with existing experimental data. (author). 22 refs.; 3 figs.}

place = {JINR}

year = {1994}

month = {Dec}

}