### Conveners

#### Parallel session B2: Light Mesons and Baryons 2

- Michal Praszalowicz (Jagiellonian University)

The state pi1(1600) has exotic quantum numbers 1^-+ and is rightfully treated as a hybrid (quark-antiquark-gluon) candidate. Recently, the eta1(1855) has been experimentally discovered. It is then natural to expect that a whole nonet of hybrid states must exist: besides the two states above, a kaonic hybrid and a light eta1 hybrid should exist as well. Predictions and postdictions for the...

A dispersive implementation of the $a_0(980)$ resonance to (g-2) requires the knowledge of the double-virtual S-wave $\gamma^*\gamma^*\to\pi\eta, K K$ amplitudes. To obtain these amplitudes we used a modified coupled-channel Muskhelishvili–Omnès formalism, with the input from the left-hand cuts and the hadronic Omnès function. The latter we obtained using a data-driven N/D method in which the...

Tetraquark mixing model has been proposed recently as a possible structure for the two nonets in the $J^P=0^+$ channel, the light nonet composed of $a_0(980)$, $K_0^*(700)$, $f_0(500)$, $f_0(980)$, and the heavy nonet of $a_0(1450)$, $K_0^*(1430)$, $f_0(1370)$, $f_0(1500)$. Two tetraquark types are introduced in this model, and their mixtures that diagonalize the color-spin interaction are...

We present recent results on the dynamical generation of the $a_1$, $h_1$, and $b_1$ axial-vector mesons. We demonstrate the emergence of the $a_1$ and $h_1$ mesons from the $\pi\rho$ scattering process, based on the coupled-channel formalism with the $\pi\rho$ and $K\bar{K}^*$ ($\bar{K}K^*$) channels. This is achieved by constructing kernel amplitudes using the effective Lagrangian and...

We calculate the differential cross section dσ/dt for the diffractive photoproduction process γp→ρp and compare to recent data extracted by the CMS collaboration. Our model is based on two-gluon exchange in the nonperturbative domain. We take into account both helicity conserving and often neglected helicity-flip amplitudes in the γ→V transition, which can contribute at finite t. The shape of...