Speaker
Description
Experimental measured value of the muon magnetic moment $a_{\mu} = \frac{g_{\mu}-2}{2}$ has a long-standing and well known discrepancy comparing with Standard Model prediction that has been narrowed down within a range $3.2-3.6\,\sigma$ after years of efforts made by experimentalists and theoreticians. Previous results of dipion cross section $\sigma_{\pi\pi} = \sigma(e^+e^-\to\pi^+\pi^-)$ from KLOE have provided comprehensive and substantial studies on the largest experimental input from hadronic contribution. In order to deepen the understand of theoretical uncertainty for $a_{\mu}$, it is natural to extent the studies to three pion cross section, which is the second largest hardronic contribution to $a_{\mu}$.
The initial state radiation (ISR) process $e^{+}e^{-}\to3\pi$ has been studied at a center-of-mass energy $\sqrt{s}\approx1.019$ GeV close to the $\phi$ resonance using a $1.7~{\rm fb}^{-1}$ data sample collected with KLOE detector at the DA$\Phi$NE year 2004/2005. In this analysis, we have studied the visible section $\sigma^{\rm vis}_{3\pi}$ of process $e^{+}e^{-}\to\pi^{+}\pi^{-}\pi^{0}$ for the effective center-of-mass energy $\sqrt{s'}$ corresponds to omega mass range $M_{3\pi}\in[720, 900]$ ${\rm MeV}/c^{2}$. With the same dataset, a further study of $\mathcal{C}$-violating decay $e^{+}e^{-}\to\phi\to\omega\gamma$ is being performed based on a careful investigation of the ISR process, which is the major background with identical $3\pi$ final state.
