Speaker
Description
Through the 21st and 22nd International Workshop on Deep Inelastic Scattering, a possibility of the non-perturbative contribution for the non-zero transverse single spin asymmetry of forward $\pi^{0}$ ($2 < \eta < 4$) was brought up. Bigger asymmetry was observed with more isolated final state which was connected with the non-perturbative event topology. Since the non-perturbative contribution has been studied by only the forward $\pi^{0}$ production where the perturbative process was expected to be the major interaction rather than non-perturbative one, the RHICf experiment measured the very forward ($\eta > 6$) $\pi^{0}$ to study the non-perturbative contribution in more detail. A new electromagnetic calorimeter was installed for the operation at the zero-degree region of the STAR experiment at RHIC and measured the $\pi^{0}$ over the kinematic range of $x_{F} > 0.25$ and $0 < p_{T} < 1$ GeV/$c$ in June, 2017. A clear non-zero asymmetry was observed even in low $p_{T} < 1$ GeV/$c$ showing a similar $x_{F}$ dependence with the forward $\pi^{0}$ one as the $p_{T}$ approached to 1 GeV/$c$. We present the first measurement of the very forward $\pi^{0}$ asymmetry, its analysis procedure and preliminary result. A future aspect to more precisely study the non-perturbative contribution will be also introduced.
