scholarly journals PION FORM FACTOR IN QCD SUM RULES WITH NONLOCAL CONDENSATES AND IN THE LOCAL-DUALITY APPROACH

2009 ◽  
Vol 24 (35n37) ◽  
pp. 2848-2857 ◽  
Author(s):  
A. P. BAKULEV ◽  
A. V. PIMIKOV ◽  
N. G. STEFANIS
Keyword(s):  
Form Factor ◽  
Sum Rules ◽  
Pion Form Factor ◽  
Analytic Perturbation Theory ◽  
Continuum Threshold ◽  
Sum Rule ◽  
Local Duality ◽  
Rule Approach ◽  
Duality Approach ◽  
The Continuum

We discuss the QCD sum-rule approach for the spacelike electromagnetic pion form factor in the O(αs) approximation. We show that the nonlocality of the condensates is a key point to include nonperturbative contributions to the pion form factor. We compare our results with the Local-Duality predictions and show that the continuum threshold s0(Q2) parameter is highly underestimated in the Local-Duality approach at Q2 ≳ 2 GeV 2. Using our fit for this parameter, [Formula: see text] and applying the fractional analytic perturbation theory, we estimate with an accuracy of the order of 1% the [Formula: see text] contribution to the pion's form factor.

THE FORM FACTOR OF ργ*→π0IN THE FINITE-WIDTH LIGHT-CONE LOCAL DUALITY SUM RULE

2012 ◽  
Vol 21 (04) ◽  
pp. 1250048
Author(s):  
MINGHAI LI ◽  
JUEPING LIU
Keyword(s):  
Form Factor ◽  
Light Cone ◽  
Asymptotic Form ◽  
Sum Rules ◽  
Absorptive Part ◽  
Finite Width ◽  
Transition Form ◽  
Sum Rule ◽  
Local Duality ◽  
The Difference

The form factor of the transition ργ*→π0is investigated by analyzing the γγ*→π0transition in the framework of the light-cone local duality quantum chromodynamics sum rules. Both finite- and zero-width forms for the low-energy physical absorptive part of the γγ*→π0transition are considered. The numerical results for the transition form factor Fρπ(Q2) in the asymptotic form and the CZ one of the pion distribution amplitude are obtained respectively, the difference between the finite- and zero-width form is not big but still distinguishable. It is found that the results for the form factor Fρπ(Q2) from CZ, asymptotic and the flat pion DAs are compatible with the predictions of perturbative QCD. Our results will be helpful to distinguish the shape of the pion DA of twist-two, when the concrete information of the experimental data for the transition ργ*→π0are provided.

scholarly journals Form factor π0γ*γ in lightcone sum rules combined with renormalization-group summation vs experimental data.

2019 ◽  
Vol 222 ◽  
pp. 03017 ◽  
Author(s):  
C. Ayala ◽  
S. V. Mikhailov ◽  
A. V. Pimikov ◽  
N. G. Stefanis
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Renormalization Group ◽  
Form Factor ◽  
Transition Form Factor ◽  
Sum Rules ◽  
Transition Form ◽  
Analytic Perturbation Theory ◽  
Sum Rule ◽  
Fixed Order

We consider the lightcone sum-rule (LCSR) description of the pionphoton transition form factor in combination with the renormalization group of QCD. The emerging scheme represents a certain version of Fractional Analytic Perturbation Theory and significantly extends the applicability domain of perturbation theory towards lower momenta Q2 ≲ 1 GeV2. We show that the predictions calculated herewith agree very well with the released preliminary data of the BESIII experiment, which have very small errors just in this region, while the agreement with other data at higher Q2 is compatible with the LCSR predictions obtained recently by one of us using fixed-order perturbation theory.

scholarly journals Pion form factor at spacelike momentum transfers from local-duality QCD sum rule

2008 ◽  
Vol 661 (5) ◽  
pp. 354-359 ◽  
Author(s):  
Victor Braguta ◽  
Wolfgang Lucha ◽  
Dmitri Melikhov
Keyword(s):  
Form Factor ◽  
Pion Form Factor ◽  
Sum Rule ◽  
Local Duality

scholarly journals REVIEW ON QCD SUM RULES CALCULATIONS FOR EXOTICS CHARMONIUM

2011 ◽  
Vol 02 ◽  
pp. 36-40
Author(s):  
MARINA NIELSEN
Keyword(s):  
Sum Rules ◽  
Mass Region ◽  
Qcd Sum Rules ◽  
Sum Rule ◽  
Rule Approach ◽  
New States

Many new states in the charmonium mass region were recently discovered by the BaBar, Belle and CDF Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.

QCD SUM RULE APPROACH TO THE K→VACUUM WEAK AMPLITUDE

1990 ◽  
Vol 05 (06) ◽  
pp. 1071-1091
Author(s):  
M.A. AHMED ◽  
M.S. RASHEED
Keyword(s):  
Matrix Element ◽  
Sum Rules ◽  
Finite Energy ◽  
The Other ◽  
Sum Rule ◽  
Rule Approach ◽  
The Matrix

We study the kaon-to-vaccum weak matrix element using the method of the QCD duality finite energy sum rules. It is found that the matrix element in question can be expressed as a sum of two terms: one behaving like ms−md and the other like [Formula: see text]. Detailed numerical estimates are also given.

Sum rules and the pion form factor in QCD

1982 ◽  
Vol 115 (5) ◽  
pp. 410-414 ◽  
Author(s):  
V.A. Nesterenko ◽  
A.V. Radyushkin
Keyword(s):  
Form Factor ◽  
Sum Rules ◽  
Pion Form Factor
Sign in / Sign up

Export Citation Format

Share Document