PoS - Proceedings of Science
Volume 310 - XVII International Conference on Hadron Spectroscopy and Structure (Hadron2017) - Session 6: QCD and hadron structure
Charge Symmetry Breaking in the Reaction $dd\to \,^4{\rm He} \, \pi^0$ with WASA-at-COSY
M. Zurek* on behalf of the WASA-at-COSY Collaboration
*corresponding author
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Pre-published on: February 16, 2018
Published on: March 20, 2018
The presented analysis concentrates on the charge symmetry breaking reaction $dd \rightarrow {}^4\text{He}\pi^0$. The aim is to provide experimental results for comparison with chiral perturbation theory (ChPT) to study effects induced by quark masses on the hadronic level. In this paper the second measurement of the $dd \rightarrow {}^4\text{He}\pi^0$ reaction at $Q = 60$ MeV using an improved WASA detector setup aiming at higher statistics is described. The total and differential cross sections have been determined. The preliminary result of the total cross section is $\sigma^{\text{tot}}_{\text{prel}} = (74.3 \pm 6.8 (\text{stat.}) ^{+1.2}_{-10.1}(\text{syst.}) \pm 7.7 (\text{norm.})) \text{pb}$. The angular distribution has been described up to second order in $\cos\theta^*$ with a function of the form $\text{d}\sigma/\text{d}\Omega = a + b\cos^{2}\theta^*$, where $\theta^*$ is the scattering angle of the pion in the c.m. coordinate system. The obtained preliminary parameters $a$ and $b$ are $a_{\text{prel}} = \left(1.55 \pm 0.46 (\text{stat}) ^{+0.32}_{-0.8} (\text{syst})\right) \text{pb/sr}$ and $b_{\text{prel}} = \left(13.1 \pm 2.1 (\text{stat}) ^{+1.0}_{-2.7} (\text{syst})\right)\text{pb/sr}$.
DOI: https://doi.org/10.22323/1.310.0157
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