Photoproduction of the $f_2(1270)$ meson using the CLAS detector

TL;DR

This study measures the photoproduction of the $f_2(1270)$ meson using the CLAS detector, providing new experimental data on its production mechanism and decay channels, which informs its underlying quark or molecular structure.

Contribution

First measurement of the reaction $oldsymbol{ ext{γ} p o ext{π}^0 ext{π}^0 p}$ for the $f_2(1270)$ meson with detailed differential cross sections at Jefferson Lab.

Findings

Differential cross sections for $f_2(1270)$ photoproduction were obtained with high precision.

Results are compared with theoretical models, providing insights into the meson's structure.

Data suggest possible implications for the meson's quark or molecular state nature.

Abstract

The quark structure of the $f_2(1270)$ meson has, for many years, been assumed to be a pure quark-antiquark ($q\bar{q}$) resonance with quantum numbers $J^{PC} = 2^{++}$. Recently, it was proposed that the $f_2(1270)$ is a molecular state made from the attractive interaction of two $\rho$-mesons. Such a state would be expected to decay strongly to final states with charged pions, due to the dominant decay $\rho \to \pi^+ \pi^-$, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction $\gamma p \to \pi^0 \pi^0 p$, using the CLAS detector at Jefferson Lab for incident beam energies between 3.6-5.4~GeV. Differential cross sections, $d\sigma / dt$, for $f_2(1270)$ photoproduction are extracted with good precision, due to low backgrounds, and are compared with theoretical calculations.