_{1}(1269) resonance in the γ

^{+}π

^{+}π

^{-}

Supported by the National Natural Science Foundation of China (11475227, 11735003), and the Youth Innovation Promotion Association CAS (2016367)

^{3}and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd

Within an effective Lagrangian approach and resonance model, we study the

_{1}(1260)

Article funded by SCOAP^{3}

The

The dynamically generated nature of

Based on the values obtained by two different experimental groups [^{②}

The result reported by COMPASS provides the mass

Meson photoproduction off a proton provides one of the most direct platforms to extract information about the hadronic structure [

The article is organized as follows. After the introduction, we present the reaction mechanism of

In this section, we discuss the

Feynman diagram for the

For the

where the standard value,

where

The vertex depicting the interaction of

where

With the vertex above, we can easily get the partial decay width of

where

With the above integrants, one can get the scattering amplitude of the

By defining

where

In

Dependence of the total cross-section of
_{γ}

Next, we consider the

The

Feynman diagram for the

The

where

For the vertex of

with a typical value of

The

where the width

where

For the structure of the

where

For the vertex of

with a typical value of

The

where

with

where

It is worth to mention that the parametrization of the width of

We finally obtain the scattering amplitude for the diagram shown in

Besides the resonance contribution of the

Feynman diagram for the

To compute the contribution of

where

Other vertexes are the same as given above. With the above preparation, we get the transition amplitude for the diagram shown in

with

where

The total cross-section of the

with

where 2! is a statistical factor for the final two

where

In Ref. [

The 3

In addition to the differential cross-section, we also calculated the total cross-section for the

Total cross-section for the

In recent years, it has been found that the

In addition, taking the coupling constant obtained from the picture where the

2) The result reported by COMPASS provides the mass