We investigate the preformation probability of the light particle that formed in the preliminary stage of the ternary fission process of the ${}^{252}\mathrm{Cf}$ nucleus. Considering the equatorial cluster tripartition kinematics, the relative yields of the ternary fission channels with ${}^{4,6}\mathrm{He}, {}^{10}\mathrm{Be}$ and ${}^{14}\mathrm{C}$ as light third nucleus, are calculated. We use the Wentzel-Kramers-Brillouin approximation to calculate the penetrability of the different nuclei involved in the ternary fission process, based on microscopic Skyrme potentials. The obtained results indicate the optimum total excitation energy of the heavy nuclei produced in the $\alpha$ ternary fission channels to be within the range of 3–4 MeV. The estimated $\alpha$-preformation probability corresponding to this range is comparable with that estimated for the spontaneous $\alpha$ decays of the participating heavy nuclei. While the extracted preformation probability at excitation energy less than its indicated optimum values exhibits unphysical large values, the calculations based on the higher excitation energies indicate extremely small values. In the ternary fission process, the preformation probability of the emitted light particles heavier than the $\alpha$ particle exponentially decreases with increasing its mass number. A phenomenological expression is suggested based on the obtained results to estimate the preformation probability of an emitted cluster of a given mass number.

The multiphase transport model is used to investigate the longitudinal broadening of the transverse momentum two-particle correlator $C_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$, and its utility to extract the specific shear viscosity, $\eta /s$, of the quark-gluon plasma formed in ultrarelativistic heavy ion collisions. The results from these model studies indicate that the longitudinal broadening of $C_2(\mathrm{\Delta }\eta ,\mathrm{\Delta }\phi )$ is sensitive to the value of $\eta /s$. However, reliable extraction of the longitudinal broadening of the correlator requires the suppression of possible self-correlations associated with the definition of the collision centrality.

Background: The ${}^6\mathrm{Li}(p,\gamma ){}^7\mathrm{Be}$ cross section influences a variety of astrophysical scenarios, including big-bang and stellar nucleosynthesis. In recent years, conflicting results of direct measurements have been published, reporting contradictory low-energy trends.

Purpose: To shed light on the contradiction between the existing data sets, the reaction was studied using the asymptotic normalization coefficient (ANC) technique which was up-to-now never used for this reaction.

Methods: To derive the ANC, the ${}^6\mathrm{Li}({}^3\mathrm{He},d){}^7\mathrm{Be}$ transfer reaction, studied at the Department of Physics and Astronomy of the University of Catania and at the John. D. Fox Superconducting Accelerator Laboratory at Florida State University, was re-analyzed, focusing on the proton transfer mechanism [the $\alpha$ transfer process is discussed by Kiss et al. [Phys. Lett. B 807, 135606 (2020)]. The energy of the ${}^3\mathrm{He}$ beam impinging on a ${}^6\mathrm{Li}$ target was $E_{\mathrm{lab}}=3$ MeV and $E_{\mathrm{lab}}=5$ MeV. The yield of the emitted deuterons was measured with high precision by using silicon $\mathrm{\Delta }E-E$ telescopes.

Results: From the DWBA analysis of the angular distributions of the emitted deuterons populating the ground ($E^{*}=0.0$ MeV; ${\frac{3}{2}}^{-}$) and the first excited ($E^{*}=0.429\mathrm{MeV}$; ${\frac{1}{2}}^{-}$) states of ${}^7\mathrm{Be}$, the ANCs for the ${}^6\mathrm{Li}+p\to {}^7\mathrm{Be}$ system were deduced. Furthermore, the recently measured ${}^6\mathrm{Li}(p,\gamma ){}^7\mathrm{Be}$ reaction cross sections [Piatti et al., Phys. Rev. C 102, 052802 (2020)] were also analyzed within this theoretical framework. Excellent agreement was found between ANC values derived indirectly and those determined from the direct data, which strengthens the conclusion of the present work. The astrophysical $S$ factor—at energies characterizing the Sun—for the ${}^6\mathrm{Li}(p,\gamma ){}^7\mathrm{Be}$ reaction was calculated using the weighted mean of the experimentally derived ANC values.

Conclusions: The result of the present comprehensive study supports the extrapolation of Piatti et al. [Phys. Rev. C 102, 052802 (2020)], Dong et al. [J. Phys. G Nucl. Partic. 44, 045201 (2017)], and Gnech and Marcucci [Nucl. Phys. A 987, 1 (2019)], and thus disfavors the conclusions drawn by He et al. [Phys. Lett. B 725, 287 (2013)] and Xu et al. [Nucl. Phys. A 918, 61 (2013)].

Recent experiments performed in neutron-rich copper isotopes have revealed a crossing in the nucleus ${}^{75}\mathrm{Cu}$ between the $3/2^{-}$ and $5/2^{-}$ levels, which correspond to the ground state and the first excited state in isotopes with mass number below $A=75$. Due to the strong single-particle character of these states, this scenario can be investigated through the analysis of the proton spectrum provided by mean-field models in nickel isotopes with neutron numbers between $N=40$ and $N=50$. In this work, we show that the aforementioned crossing is mainly driven by the mean field provided by the effective nucleon-nucleon and spin-orbit interactions. We also analyze the impact of the tensor interaction and find that in some mean-field models it is essential to reproduce the crossing of the $2p_{3/2}$ and $1f_{5/2}$ proton single-particle levels, as in the case of the SAMi-T Skyrme force and the D1M Gogny interaction, whereas in other cases, as for example the SLy5 Skyrme force, a reasonable tensor force appears to be unable to modify the mean-field enough to reproduce this level crossing. Finally, in the calculations performed with the so-called simple effective interaction (SEI), it is shown that the experimental data in nickel and copper isotopes considered in this work can be explained satisfactorily without any explicit consideration of the tensor interaction.

The nuclear matrix elements of neutrinoless double-$\beta$ decay for nuclei ${}^{76}\mathrm{Ge}$, ${}^{82}\mathrm{Se}$, ${}^{100}\mathrm{Mo}$, ${}^{130}\mathrm{Te}$, and ${}^{150}\mathrm{Nd}$ are studied within the triaxial projected shell model, which incorporates simultaneously the triaxial deformation and quasiparticle configuration mixing. The low-lying spectra, the $B(E2:0^{+}\to 2^{+})$ values, and the occupancies of single-particle orbits are reproduced well. The effects of the quasiparticles configuration mixing, the triaxial deformation, and the closure approximation on the nuclear matrix elements are studied in detail. For nuclei ${}^{76}\mathrm{Ge}$, ${}^{82}\mathrm{Se}$, ${}^{100}\mathrm{Mo}$, ${}^{130}\mathrm{Te}$, and ${}^{150}\mathrm{Nd}$, the nuclear matrix elements are respectively reduced by the quasiparticle configuration mixing by 6%, 7%, 2%, 3%, and 4%, and enhanced by calculating explicitly the transitions through odd-odd intermediate states by 7%, 4%, 11%, 20%, and 14%. Varying the triaxial deformation $\gamma$ from $0^{\circ }$ to ${60}^{\circ }$ for the mother and daughter nuclei, the nuclear matrix elements change by 41%, 17%, 68%, 14%, and 511%, respectively, for ${}^{76}\mathrm{Ge}$, ${}^{82}\mathrm{Se}$, ${}^{100}\mathrm{Mo}$, ${}^{130}\mathrm{Te}$, and ${}^{150}\mathrm{Nd}$, which indicates the importance of treating the triaxial deformation consistently in calculating the nuclear matrix elements.

Rotational bands in ${}^{109}\mathrm{Rh}$ are investigated in a simple model and in the interacting boson-fermion model. We have developed a solvable extended transitional Hamiltonian by adding a two-configuration mixing term. Results suggest that ${}^{109}\mathrm{Rh}$ is a good candidate for triaxiality and shape coexistence. Mixing between $3/2^{+}$ states with $K=1/2$ and 3/2 is found to be weak, as evidenced by the $E2$ strengths.

The chiral quark-meson coupling (CQMC) models are applied to revisiting static properties of spherical nuclei in comparison with the results from the conventional quantum hadrodynamics (QHD)-like models as well as the available experimental data. They are also used to describe the nuclei off which the electrons scatter to understand their dynamic properties. After calibrating the model parameters at equilibrium nuclear matter density, binding energies, charge radii, single-particle spectra, and density distributions of the nuclei are analyzed and compared. The nonlinear scalar self-interaction in each model is also discussed in consideration of the reproduction of nuclear saturation properties.

Higher order symmetric cumulants of global collective observables in heavy ion collisions are studied. The symmetric cumulants can be straightforwardly constructed for scalar observables: the average transverse momentum, the multiplicity, and the squares of harmonic flow vectors. Third and fourth order cumulants are calculated in the hydrodynamic model. A linear predictor of the average transverse momentum and harmonic flow coefficients in a collision is used to predict the values of the cumulants from the moments of the initial distribution. The symmetric cumulants divided by the averages (or the standard deviations) of the considered observables can be used as a fine tool to study correlations present in the initial state of the collision.

Heavy-ion collisions at the Large Hadron Collider provide the conditions to investigate regions of quark-gluon plasma that reach higher temperatures and that persist for longer periods of time compared with collisions at the Relativistic Heavy Ion Collider. This extended duration allows correlations from charge conservation to better separate during the quark-gluon plasma phase, and thus be better distinguished from correlations that develop during the hadron phase or during hadronization. In this study charge balance functions binned by relative rapidity and azimuthal angle and indexed by species are considered. A detailed theoretical model that evolves charge correlations throughout the entirety of an event is compared with preliminary results from the ALICE Collaboration. The comparison with experiment provides insight into the evolution of the chemistry and diffusivity during the collision. A ratio of balance functions is proposed to better isolate the effects of diffusion and thus better constrain the diffusivity.

To test the contributions of the quark subprocesses to the inclusive diffractive heavy quarkonium photoproduction, we first investigate the inclusive nondiffractive direct and resolved photoproduction of $J/\mathrm{\Psi }$ in the framework of nonrelativistic quantum chromodynamics (NRQCD). We find that the theoretical total cross section of heavy quarkonium productions are in good agreement with the data available at HERA, once the $\gamma q$, $qg$, and $qq$ subprocesses in the heavy quark pair productions are taken into account. Then we predict the inclusive diffractive rapidity and transverse momentum distributions of $J/\mathrm{\Psi }$, $\mathrm{\Psi }\left(2S\right)$, and $\mathrm{{\rm Y}}\left(1S\right)$ in $pp$, $p\mathrm{Pb}$, and $\mathrm{PbPb}$ collisions at the CERN Large Hadron Collider by using our quark improved NRQCD model. We find that the contributions from the quark involved subprocesses to quarkonium photoproduction are about $6\%\text{–}15\%$. The numerical results show that the contributions from quark involved subprocesses are significant modification in inclusive diffractive heavy quarkonium photoproduction.

The isospin-asymmetry nuclear chains with $N-Z$ from 2 to 60 are investigated to find the correlations of $\alpha$-decay properties and isospin asymmetry. Both the proton- and neutron-skin thicknesses of $\alpha$ emitters belonging to different $N-Z$ chains are tightly aligned along straight lines, the slope of which depends on the shell closure. For even-even $\alpha$ emitters, the neutron-skin thickness ${\mathrm{\Delta }}_n$ multiplied by $N-Z$ is a parabolic function of the isospin-asymmetry parameter $I=(N-Z)/A$. For the nuclei of incomplete neutron shells, the $\alpha$-decay half-life $T_{\alpha }$ exponentially increases with ${\mathrm{\Delta }}_n$ in the isospin chain. In the nuclei with valence neutrons and/or protons outside the magic core, $T_{\alpha }$ exponentially decreases with increasing ${\mathrm{\Delta }}_n$. The values of $T_{\alpha }$ and $Q_{\alpha }$ are almost exponential functions of isospin asymmetry.

The recently updated parity doublet structures in ${}^{223}\mathrm{Th}$ are investigated by using the reflection-asymmetric triaxial particle rotor model. The calculated results well reproduce the available data of the energy spectra and the $B\left(E1\right)/B\left(E2\right)$ ratios for both medium spin region and the newly established higher spin region, as well as the average value of $B\left(M1\right)/B\left(E2\right)$ for spins $9/2\hslash$ and $11/2\hslash$ in the positive-parity band. The main components of the intrinsic wave functions are analyzed to investigate the intrinsic wave functions and their evolutions with spin. The parity doublet bands are mainly based on a single neutron configuration, in which the largest component of the intrinsic wave function is $\nu (g_{9/2},j_{15/2})[\mathrm{\Omega }=5/2]$ and the second largest one is $\nu (g_{9/2},j_{15/2})[\mathrm{\Omega }=3/2]$. The amplitude of the largest component decreases whereas the second largest one increases with increasing spin, and the signature splitting behavior for the parity doublet bands could be understood by the variation of these main components with spin.

Background: Spin-triplet $(S=1)$ proton-neutron $\left(pn\right)$ pairing in nuclei has been under debate. It is well known that the dynamical pairing affects the nuclear matrix element of the Gamow-Teller (GT) transition and the double $\beta$ decay.

Purpose: We investigate the effect of the $pn$-pair interaction in the $T=0,S=1$ channel on the low-lying spin-dipole (SD) transition. We then aim at clarifying the distinction of the role in between the SD and GT transitions.

Method: We perform a three-body model calculation for the transition ${}^{80}\mathrm{Ni}\to {}^{80}\mathrm{Cu}$, where ${}^{78}\mathrm{Ni}$ is taken as a core. The strength of the pair interaction is varied to see the effect on the SD transition-strength distribution. To fortify the finding obtained by the three-body model, we employ the nuclear energy-density functional method for the SD transitions in several nuclei, where one can expect a strong effect.

Results: The effect of the $S=1pn$-pair interaction depends on the spatial overlap of the $pn$ pair and the angular momentum of the valence nucleons; the higher the angular momentum of the orbitals, the more significant the effect.

Conclusions: The dynamical $S=1$ pairing is effective even for SD states, although the spatial overlap of the $pn$ pair can be smaller than GT states. The SD transition involving high-$\ell$ orbitals with the same principal quantum number is strongly affected by the dynamical $S=1$ pairing.

In this paper, the excitation function utilizing the nuclear reaction ${}^{\mathrm{nat}}\mathrm{V}(p,X)$ ${}^{44}\mathrm{Ti}$ was determined. The seven investigated metallic vanadium disks were proton irradiated within an energy range of 111–954 MeV between 1995 to 1996. The experiments' cross sections were validated using two independent measurements by combining $\gamma$ spectrometry with both a low-energy germanium detector and a high-purity germanium detector. The maximum cross section was observed for energies of 145 $\pm$ 1.2 and 150.2 $\pm$ 1.2 MeV with values of 803 $\pm$ 28 and 805 $\pm$ 27 $\mu \mathrm{b}$, respectively. In this regard, it was demonstrated that our data were in good agreement with the former, however, unpublished results which were investigated over a similar energy range. Thus, combined with these earlier measurements, a consistent data set for the ${}^{\mathrm{nat}}\mathrm{V}(p,X)$ ${}^{44}\mathrm{Ti}$ excitation function from 111 to 1350 MeV is provided. Model calculations using Liège Intranuclear Cascade (INCL)/ABLA reproduce the shape of the excitation function correctly but overpredict the absolute values by factors of 2 to 3. Some considerations regarding this already earlier observed systematic overestimation of neutron-poor residues are given. The results will trigger new approaches in code development in order to improve the predictions.

We evaluate the cross section for gamma production by neutrinos through a meson exchange effect which derives from the concept of axial-vector mixing. The resulting cross section leads to some increase of the gamma production cross section by neutrinos, especially at low neutrino energies, which may influence the understanding of the low-energy excess of electron-like events seen in the MiniBooNE experiment.

We develop a model for the $pp\to {\pi }^{+}d$ reaction based on the $pp\to \mathrm{\Delta }\left(1232\right)N$ transition followed by $\mathrm{\Delta }\left(1232\right)\to \pi N^{\prime }$ decay and posterior fusion of $N{N}^{\prime }$ to give the deuteron. We show that the triangle diagram depicting this process develops a triangle singularity leading to a large cross section of this reaction compared to ordinary fusion reactions. The results of the calculation also show that the process is largely dominated by the $pp$ system in $L=2$ and $S=0$, which transfers $J=2$ to the final ${\pi }^{+}d$ system. This feature is shown to be well suited to provide $L=2$, $S=1$, and $J^{\mathrm{tot}}=3$ for $np$ in the $np(I=0)\to {\pi }^{-}pp$ reaction followed by the $pp\to {\pi }^{+}d$ reaction, which has been proposed recently, as a means of describing the so far assumed dibaryon $d^{*}\left(2380\right)$ peak.

Decorrelation of the elliptic flow in rapidity is calculated within a hybrid approach which includes event-by-event viscous fluid dynamics and final state hadronic cascade model. The simulations are performed for $\mathrm{Au}+\mathrm{Au}$ collisions at center-of-mass collision energies of 27 and 200 GeV per nucleon pair, as well as various asymmetric colliding systems at 72 GeV per nucleon pair. Initial conditions determined by an extended Monte Carlo Glauber model show better agreement with experimental data than initial conditions from the ultrarelativistic quantum molecular dynamics transport model. We show how the observed decorrelation is connected with the decorrelation of initial state spatial anisotropies. We also study how the effect is increased by the final state hadronic cascade.

We present a study of the reaction ${\pi }^{-}p\to n{e}^{+}{e}^{-}$ for $\sqrt{s}=1.49\mathrm{GeV}$, including nonresonant Born terms and contributions of the $N\left(1440\right), N\left(1520\right), N\left(1535\right)$ resonances ($\mathrm{R}$), using an effective-Lagrangian model, which we extended by a phenomenological phase factor at the $\mathrm{R}N\rho$ vertex function. We give predictions for both the differential cross section $d\sigma /d{m}_{\mathrm{inv}}$ and the spin density matrix elements of the virtual photon that decays into the lepton pair. In the studied energy range, the cross section is dominated by the Born and $N\left(1520\right)$ contributions.

We compute the density dependence of the quark condensate and how it changes under the influence of isospin-asymmetric nuclear matter. This is achieved by the calculation of the relevant Feynman diagrams using in-medium chiral perturbation theory. We find that the absolute value of the quark condensate decreases in nuclear matter by around $35\%$ at normal nuclear density, in agreement with previous model-independent calculations. We also present an quantitative estimation of the difference of up- and down-quark in-medium condensates.