This article is cited in 102 papers

FIELDS, PARTICLES, AND NUCLEI

On the Pion Distribution Amplitude Shape

M. V. Polyakov<sup>ab

a</sup> Institut für Theoretische Physik II, Ruhr-Universität Bochum, D--44780 Bochum, Germany
^b Petersburg Nuclear Physics Institute, Russian Academy of Sciences

Abstract: We argue that the recent BaBar data on $\gamma\to\pi$ e.m. transition form factor at large photon virtuality supports the idea that pion distribution amplitude (DA) is close to unity with $\phi_\pi^\prime(0)/6\gg 1$ at a normalization point of $\mu=0.6\div 0.8$ GeV. Such pion DA can be obtained in the effective chiral quark model. The possible flat shape of the pion DA implies that the standard expansion of the DA in Gegenbauer polynomials can be divergent. On basis of chiral models we predict that the two-pion DA should exhibit anomalous endpoint behaviour for pions in the S-wave and that such feature is absent for higher partial waves. The latter implies that the $\rho,f_2$, etc. meson DAs have no anomalous endpoint behaviour. Possible implications of such pion DA for other hard exclusive processes are shortly discussed.

PACS: 12.38.-t

Received: 07.07.2009

Language: English

 English version: Journal of Experimental and Theoretical Physics Letters, 2009, 90:4, 228–231

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