1. General Seminars

# About the pion transition form factor

## by Dr Vicente Vento (Universidad de Valencia - IFIC)

Europe/Rome
Aula Edificio 22 (Laboratori Nazionali di Frascati)

### Aula Edificio 22

#### Laboratori Nazionali di Frascati

Description
Vicente Vento, Universidad de Valencia - IFIC BABAR data on the pion transition form factor have caused concern about the theoretical description thus far employed. We present here a formalism based on a low energy description, supported by constituent quark models, and a high energy description which match at a scale of $\sim 1$ GeV. The high energy description incorporates a flat pion distribution amplitude at the matching scale $Q_0$, QCD evolution for $Q > Q_0$ and higher twist effects. The procedure produces an excellent description of the data.