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We use a sequential $R$-matrix model to describe the breakup of the Hoyle state into three $alpha$ particles via the ground state of $^8mathrm{Be}$. It is shown that even in a sequential picture, features resembling a direct breakup branch appear in the phase-space distribution of the $alpha$ particles. We construct a toy model to describe the Coulomb interaction in the three-body final state and its effects on the decay spectrum are investigated. The framework is also used to predict the phase-space distribution of the $alpha$ particles emitted in a direct breakup of the Hoyle state and the possibility of interference between a direct and sequential branch is discussed. Our numerical results are compared to the current upper limit on the direct decay branch determined in recent experiments.
Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound O26 can provide information on the ground-state wave function, which has been predicted to have a dineutron co
Electron scattering off the first excited 0+ state in 12C (the Hoyle state) has been performed at low momentum transfers at the S-DALINAC. The new data together with a novel model-independent analysis of the world data set covering a wide momentum tr
The interaction of an $E/A$=57.6-MeV $^{17}$Ne beam with a Be target was used to populate levels in $^{16}$Ne following neutron knockout reactions. The decay of $^{16}$Ne states into the three-body $^{14}$O+$p$+$p$ continuum was observed in the High
The first excited $J^pi=0^+$ state of $^{12}$C, the so-called Hoyle state, plays an essential role in a triple-$alpha$ ($^4$He) reaction, which is a main contributor to the synthesis of $^{12}$C in a burning star. We investigate the Coulomb screening
Stellar carbon synthesis occurs exclusively via the $3alpha$ process, in which three $alpha$ particles fuse to form $^{12}$C in the excited Hoyle state, followed by electromagnetic decay to the ground state. The Hoyle state is above the $alpha$ thres