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Roberto J. Liotta

Publications and source records attributed to Roberto J. Liotta.

6 recordsLinked to original sources
arXiv2026

Generalized gauge-space rotations in atomic nuclei: A critical insight

We critically reexamine the concepts of pairing rotations and moments of inertia in gauge space extracted from experimental binding energies. Our analysis focuses on pairing correlations among like nucleons, neutron-proton pairing, and $α$-type correlations. By investigating $α$ separation energies and binding-energy differences along chains of fixed isospin projection and subtracting macroscopic contributions, we reveal a remarkably smooth and nearly universal behavior in the residual $α$ correlation energy. These results exhibit the parabolic trends characteristic of collective rotations in gauge space. We demonstrate that the standard definition of the gauge-space moment of inertia for like-nucleon pairing is dominated by macroscopic contributions from Coulomb and symmetry energies. Once these are removed, the remaining moment of inertia becomes negative. This suggests that the observed behavior reflects the loss of correlation energy due to Pauli-blocking effect. Our results indicate that $α$ correlations constitute a genuine collective mode associated with quartetting dynamics arising from the coherent coupling of two superfluid components.

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arXiv2026

Three-Body Barrier Dynamics of Double-Alpha Decay in Heavy Nuclei

The simultaneous emission of two $α$ particles--double-$α$ decay--represents a long-predicted but unobserved mode of nuclear radioactivity. Here we formulate this process as a genuine three-body problem within the hyperspherical coordinate framework and evaluate decay probabilities by numerically solving the corresponding hyperradial Schrödinger equation, combined with large-scale random sampling of the potential parameters; the latter treatment ensures that the present results are more convincing. Inspired by this, we demonstrate that the penetrability ratio between simultaneous and sequential $α$ emission exhibits a strikingly linear dependence on $ZQ_{αα}^{-1/2}$, extending the barrier penetration dynamics into the correlated few-body regime. The nuclei $^{108}$Xe, $^{218}$Ra, $^{224}$Pu, $^{222}$U, $^{216}$Rn, and $^{220}$Th are suggested as the most promising candidates for the observation of double-$α$ decay, with predicted half-lives potentially accessible within present detection limits. Our results provide a unified framework for multi-$α$ decay and open a pathway to probing nuclear clustering and few-body correlations in heavy nuclei.

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arXiv2012

Effects of formation properties in one-proton radioactivity

It is shown that the proton formation probability, extracted from experimental data corresponding to one-proton radioactivity, is divided into two regions when plotted as a function of an universal parameter. This parameter is derived from a microscopic description of the decay process. In this way we explain the systematics of proton emission half-lives. At the same time the formation probability is shown to be a useful quantity to determine the deformation property of the mother nucleus.

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arXiv2009

Microscopic mechanism of charged-particle radioactivity and generalization of the Geiger-Nuttall law

A linear relation for charged-particle emissions is presented starting from the microscopic mechanism of the radioactive decay. It relates the logarithms of the decay half-lives with two variables, called $χ'$ and $ρ'$, which depend upon the $Q$-values of the outgoing clusters as well as the masses and charges of the nuclei involved in the decay. This relation explains well all known cluster decays. It is found to be a generalization of the Geiger-Nuttall law in $α$ radioactivity and therefore we call it the universal decay law. Predictions on the most likely emissions of various clusters are presented by applying the law over the whole nuclear chart. It is seen that the decays of heavier clusters with non-equal proton and neutron numbers are mostly located in the trans-lead region. The emissions of clusters with equal protons and neutrons, like $^{12}$C and $^{16}$O, are possible in some neutron-deficient nuclei with $Z\geq54$.

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arXiv2009

Universal decay law in charged-particle emission and exotic cluster radioactivity

A linear universal decay formula is presented starting from the microscopic mechanism of the charged-particle emission. It relates the half-lives of monopole radioactive decays with the $Q$-values of the outgoing particles as well as the masses and charges of the nuclei involved in the decay. This relation is found to be a generalization of the Geiger-Nuttall law in $α$ radioactivity and explains well all known cluster decays. Predictions on the most likely emissions of various clusters are presented.

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