Armen Oganesian

Axial anomaly as a collective effect of meson spectrum

Abstract We study the transition form factors of the light mesons in the kinematics, where one photon is real and other is virtual. Using the dispersive approach to axial anomaly we show that the axial anomaly in this case reveals itself as a collective effect of meson spectrum. This allows us to get the relation between possible corrections to continuum and to lower states within QCD method which does not rely on factorization hypothesis. We show, relying on the recent experimental data, that the relative correction to continuum is quite small, and small correction to continuum can dramatically change the pion form factor.

Axial Anomaly and Vector Meson Dominance Model

A connection between the axial anomaly and the vector meson dominance model is revealed for the processes of pseudoscalar meson-photon transitions. The analytic continuation of the anomaly sum rules, which are exact QCD relations following follow from the dispersive representation of the axial anomaly, to the time-like region is performed. Using these sum rules, the transition form factors of π0, η, and η′ mesons in this region are calculated. A good agreement with the available experimental data is found.

Quark-Hadron Duality, Axial Anomaly and Mixing ¶

Interplay between axial anomaly and quark-hadron duality in the presence of strong mixing is considered. The anomaly sum rule for meson transition form factors based on the dispersive representation of axial anomaly and quark-hadron duality in octet channel is analyzed. The comparison of this sum rule to the experimental data on the transition form factors of the η and η′ mesons shows that the interval of duality in this channel is rather small, contradicting the usual understanding of quark-hadron duality. The same values of interval of duality are supported by considering the two-point correlator in the local duality limit. This contradiction may be resolved by introducing of some nonperturbative non-one-pion exchange correction to the relevant spectral density. The form and value of this correction are discussed.

Transition form factors of π0,η and η′ mesons: What can be learned from anomaly sum rule?

Abstract We studied the applications of the anomaly sum rule (ASR) to the transition form factors of light pseudoscalar mesons: π 0 , η and η ′ . This nonperturbative QCD approach can be used even if the QCD factorization is broken. The status of possible small non-OPE corrections to continuum in comparison to BaBar and Belle data is explored. The accuracy of the applied method and the role of the quark mass contributions are discussed.

Axial anomaly, quark-hadron duality and transition form factors

We study the transition form factors of pseudoscalar mesons by means of anomaly sum rule — an exact relation which is a consequence of dispersive representation of axial anomaly. This sum rule (derived for the octet channel) and combined with the quark-hadron duality allows us to relate the transition form factors of η and η′ mesons. The notion of quark-hadron duality in connection with our approach is discussed and comparison with recent experimental data is done.

Search for short strings in e+e−-annihilation

In this work the behavior of power corrections to Adler finction in operator product expansion (OPE) is studied, in particular the possible contribution of operator of dimension 2. The OPE terms of dimension 4 and 6 are taken into account. Various experimental data on reactions of

Analysis of the e + e − → π0γ process using Anomaly Sum Rules approach

e^+e^-

Nonperturbative QCD and transition form factors

-annihilation to pion channels (

Axial Anomaly and Light Cone Distributions

\pi^+\pi^-

Axial Anomaly and Transition Formfactors

,