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We discuss the evolution of single particle state (SPS) energies by the deformation within a deformed Woods–Saxon potential. Since the SPS energy (SPSE) is based on the concept of one-body potential, we decompose it into kinetic and potential energy, and consider the modification of total binding energy (TBE) beyond the one-body potential by the pairing correlations. Evolution of each energy is detailed numerically. The TBEs of $$N = Z$$ nuclei in s–d shell are obtained in terms of the $$\beta _2$$ deformation by minimizing the TBE. Our results infer that a simple summation of the SPSE is not enough to explain experimental TBEs, so that we suggest how to properly obtain the TBE and the reasonable deformation beyond the deformed Woods–Saxon potential by including realistic pairing interactions by G-Matrix.

We study the Gamow-Teller (GT) and the M1 spin transitions of the s — d shell nuclei 24Mg, 26Mg, 28Si, 32S, and 36Ar by using a quasiparticle random phase approximation (QRPA) scheme that comprises neutron-proton (np), neutron-neutron (nn) and proton-proton (pp) QRPA owing to the inclusion of the np pairing, as well as nn and pp pairing correlations. At present, we work in spherical symmetry under the assumption that the deformations of the nuclei considered in this work are small enough to neglect, as was customary in past applications. For the GT transition, as well as single and double beta decays, the neutron-proton QRPA (np QRPA) is usually employed. For the M1 spin transition, the pp and nn QRPA is needed due to its neutral current property. The np pairing correlations couple the np QRPA to the nn and pp QRPA. Therefore, the coupled np + nn + pp QRPA enables us to investigate simultaneously the GT and the M1 spin transitions. In particular, in this work, detailed analyses of particle-particle and particle-hole interactions at the QRPA stage are performed for the GT and the M1 spin transitions of the well-known s — d shell N ≃ Z nuclei, and the results are compared to available data. The roles of the np pairing correlations are also discussed for those transitions.

We investigate the tensor force (TF) effect on the Gamow–Teller (GT) transition strength distributions in 42Ca, 46Ti, and 18O, which are known to have strong low-energy GT states, the so-called low-energy super GT (LeSGT) transition, peculiar to nuclei retaining a neutron number N = Z + 2. The TF is explicitly taken into account in the pairing channels of the residual interaction on top of the mean field described by a deformed Woods–Saxon potential. The pairing matrix elements (PMEs) comprising isoscalar and isovector parts, which consistently describe both the ground and the GT excited states, are calculated by a Brückner G-matrix based on the charge-dependent Bonn potential. By switching the TF on and off in the PMEs, we deduce meaningful correlations between the TF and the GT strength distributions. It is found that an attractive TF affects not only the ground state but also plays a crucial role in shifting the main GT peak to the low excitation-energy region leading to the LeSGT.

We investigate the cosmic evolutions in the extended Starobinsky model (eSM) obtained by adding one RabRab term to the Starobinsky model. We discuss the possibility of various cosmic evolutions with a special focus on the radiation-dominated era (RDE). Using simple assumptions, a second-order non-linear differential equation describing the various cosmic evolutions in the eSM is introduced. By solving this non-linear equation numerically, we show that the various cosmic evolutions, such as the standard cosmic evolution (a ∝ t 1/2) and a unique oscillating cosmic evolution, are feasible due to the effects of higher-order terms introduced beyond Einstein's gravity. Furthermore, we consider big bang nucleosynthesis (BBN), which is the most important observational result in the RDE, to constrain the free parameters of the eSM. The primordial abundances of the light elements, such as 4He, D, 3He, 7Li, and 6Li by the cosmic evolutions are compared with the most recent observational data. It turns out that most non-standard cosmic evolutions can not easily satisfy these BBN constraints, but a free parameter of the viable models with the oscillating cosmic evolution is shown to have an upper limit by the constraints. In particular, we find that the free parameter is most sensitive to deuterium and 4He abundances, which are being precisely measured among other elements. Therefore, more accurate measurements in the near future may enable us to distinguish the eSM from the standard model as well as other models.

We have studied the large-scale dynamo forced with helical magnetic energy. Compared to the kinetic forcing process, the magnetic process is not clearly observed nor intuitive. However, it may represent the actual B field amplification in the stellar corona, accretion disk, plasma lab, or other magnetically dominated systems where the strong kinetic effect does not exist. The interaction between the magnetic field and the plasma is essentially nonlinear. However, when the plasma system is driven by helical energy, whether kinetic or magnetic, the nonlinear process can be linearized with pseudotensors a, β and the large-scale magnetic field B ¯ . Conventionally, the α effect is thought to be the main dynamo effect converting kinetic energy into magnetic energy and transferring it to the large-scale regime. In contrast, β effect has been thought to diffuse magnetic energy. However, these conclusions are not based on the exact definition of α and β. In this paper, instead of the analytic definition of α and β, we derive a semi-analytic equation and apply it to the simulation data. The half analytic and numerical result shows that the averaged α effect is not so important in amplifying the B ¯ field. Rather, it is the negative β effect combined with the Laplacian (∇2 → −k 2) that plays a key role in the dynamo process. Further, the negative magnetic diffusivity accounts for the attenuation of the plasma kinetic energy E ¯ V in large scales. We discuss this process using the theoretical method and the intuitive field structure model.

We report that the standard evolution of radiation-dominated era (RDE) universe a∝t1/2 is a sufficient condition for solving a sixth order gravitational field equation derived from the Lagrangian containing BRabRab+CRR;cc as well as a polynomial f(R) for a spatially flat radiation FLRW universe. By virtue of the similarity between RabRab and R2 models up to the background order and of the vanishing property of R;cc for H=1/(2t), the analytical solution can be obtained from a special case to general one. This proves that the standard cosmic evolution is valid even within modified gravitational theory involving higher-order terms. An application of this background solution to the tensor-type perturbation reduces the complicated equation to the standard second order equation of gravitational wave. We discuss the possible ways to discriminate the modified gravity model on the observations such as the gravitational wave from the disturbed universe and primordial abundances.

We investigate roles of the tensor force (TF) on the pairing correlations in the ground-state structure of C 12 , O 16 , Ne 20 , and S 32 nuclei within a deformed BCS model. For pairing matrix elements, we exploit the Brueckner G matrix derived from the charge-dependent Bonn potential. In particular, the isoscalar (IS) neutron-proton ( n p ) pairing is studied in detail in relation to spin-triplet even TF in the nucleon-nucleon interaction. Detailed analyses of the n p pairing and possible enhancement of the IS channel are performed by focusing on roles of attractive spin-triplet even and repulsive spin-triplet odd channels in the TF for the ground states of the nuclei with some deformation. It is also shown that the TF may play a crucial role of properly interpreting the experimental data of a two-nucleon knockout reaction from C 12 .

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.

Within the framework of an optical model, the quasielastic channel experimental data for the $$^{11}$$ Be + $$^{197}$$ Au system measured at energies below and around the Coulomb barrier are analyzed. For the analysis of the $$^{11}$$ Be + $$^{197}$$ Au system, we include Coulomb dipole excitations and long-range nuclear potential to account for a long-range effects of this halo nuclear system. Using the parameters obtained from $$\chi ^{2}$$ analysis, we successfully reproduce the quasielastic experimental angular distributions for the $$^{11}$$ Be + $$^{197}$$ Au system.

We study neutrino and antineutrino emission from the direct Urca process in neutron-star matter in the presence of strong magnetic fields. We calculate the neutrino emissivity of the direct Urca process, whereby a neutron converts to a proton, an electron and an antineutrino, or a proton-electron pair converts to a neutron-neutrino pair. We solve exact wave functions for protons and electrons in the states described with Landau levels. We find that the direct Urca process can satisfy the kinematic constraints even in density regions where this process could not normally occur in the absence of a magnetic field., Comment: 15 pages, 5 figures

We investigate ground states properties of Pb isotopes located between neutron and proton drip-lines estimated by two-neutron (two-proton) separation energies and Fermi energies within the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). First, we report some candidates of nuclear shape coexistence in the isotope chain. They are accessed by calculating total energy as a function of the deformation parameter $\beta_2$, and for the coexistence candidates we take a couple of the deformation region bringing about minima of the energy within energy difference $\Delta E < $ 1 MeV. Second, the Pb isotopes near neutron drip-lines are also investigated and compared to the results by other nuclear mass models. We find out eleven neutron emitters, $^{278 - 296, 300}$Pb, giving rise to the Pb peninsular near the neutron drip-line. Finally, by exploiting the neutron and proton density we deduce the neutron skin thickness (NST) of the Pb isotopes and compare to the available experimental data. The recent data regarding the shape coexistence of $^{184,186,188}$Pb and the NST of $^{208}$Pb are shown to be well matched with the present results.

We investigate the properties of $\Lambda$ hyperon in $\Lambda$-hypernuclei using an effective nuclear density functional theory which is based on the low-energy effective field theory. It expands the energy density in the power of Fermi momentum, and consequently has multiple density dependence for the effective many-body interactions. Starting from the effective density functional for nucleons, we determine the parameters for the two- and many-body $\Lambda$-$N$ interactions added to the nucleon energy density functional by fitting to $\Lambda$-hypernuclear data. The experimental data consist of the energy levels of a $\Lambda$ hyperon in the $p$-, and $d$-states as well as $s$-state of $\Lambda$-hypernuclei in the mass range from $_\Lambda^{16}$O to $_\Lambda^{208}$Pb. The results turn out to properly explain the data relevant to hypernuclei owing to the effective many-body interaction apart from a few data in light hypernuclei. This hyperon functional is applied to study the $\Lambda$ hyperon binding energy of the neutron-rich $^{124-136}_\Lambda$Sn isotopes which are under consideration for the measurement at J-PARC. Our results are shown to be insensitive to the density dependence of symmetry energy. We also examine the nuclear matter including $\Lambda$ hyperon. We note that the hyperon threshold density depends on the nuclear matter properties., Comment: 22 pages, 3 tables, 8 figures

Many regions of the universe are in a state of hot, magnetized, and ionized X-ray emitting plasmas. We numerically simulated the energy spectrum of this highly viscous and conductive system. Without magnetic field, the fluctuating plasma motion decays in a relatively large viscous scale l ν (∼1/k ν ). However, the magnetic field extends the viscous scale to the magnetic diffusivity one l η (∼1/k η ) yielding a unique energy spectrum. Numerical simulation shows that kinetic and magnetic energy spectrum are E V ∼ k −3.7 and E M ∼ k −0.85 in the extended viscous scale regime. To explain this extraordinary power law, we set up two simultaneous differential equations for E V and E M and solved them using Eddy Damped Quasi Normal Markovianized approximation. Focusing on the most dominant terms, we analytically derived the spectrum relation E M 2 ∼ k 2 E V consistent with the simulation data. We also simulated the same system with helical energy. The inversely cascaded magnetic energy makes the spectrum steeper. This inverse energy transfer, in addition to the external magnetic field and instabilities, provides us a clue to the diversified spectra characterized by E V ∼ k −3.8 − k −3.07 and E M ∼ k −2.17 − k −0.27 with large magnetic Prandtl number.

Using the relativistic mean-field model with nonlinear couplings between the isoscalar and isovector mesons, we study the properties of isospin-asymmetric nuclear matter. Not only the vector mixing, $\omega_{\mu}\omega^{\mu}\mathbf{\rho}_{\nu}\mathbf{\rho}^{\nu}$, but also the quartic interaction due to the scalar mesons, $\sigma^{2}\mathbf{\delta}^{2}$, is taken into account to investigate the density dependence of nuclear symmetry energy, $E_{\rm sym}$, and the neutron-star properties. It is found that the $\delta$ meson increases $E_{\rm sym}$ at high densities, whereas the $\sigma$-$\delta$ mixing makes $E_{\rm sym}$ soft above the saturation density. Furthermore, the $\delta$ meson and its mixing have a large influence on the radius and tidal deformability of a neutron star. In particular, the $\sigma$-$\delta$ mixing reduces the neutron-star radius, and, thus, the present calculation can simultaneously reproduce the dimensionless tidal deformabilities of a canonical $1.4M_{\odot}$ neutron star observed from the binary neutron star merger, GW170817, and from the compact binary coalescence, GW190814., Comment: 11 pages, 14 figures, 2 tables

We have proposed a short-lived radioisotope 98Tc as the nuclear cosmochronometer to evaluate the time from the last supernova neutirno-process to the solar system formation (SSF). We have calculated the supernova neutirno-process using a SN 1987A model with neutrino-induced reaction cross sections. The calculated result is consistent with the observed upper limit of 98Tc/98Ru at the SSF.

The neutrino process ($\nu$-process) for the production of 7Li and 11B in core-collapse supernovae (SNe) is extensively investigated. Initial abundances of s-nuclei and other physical conditions are derived from an updated calculation of the SN 1987A progenitor. The nuclear reaction network including neutrino reactions is constructed with the variable order Bader-Deuflhard integration method. We find that yields of 7Li and 11B significantly depend on the stellar metallicity while they are independent of the weak s-process during the stellar evolution. When the metallicity is high, there are more neutron absorbers, i.e., 56Fe, 14N (from initial CNO nuclei), and 54Fe, and the neutron abundance is small during the $\nu$-process. Since 7Be is predominantly destroyed via 7Be(n,p)7Li, a change in the neutron abundance results in different 7Be yields. Then, the calculated yield ratio 7Li/11B=0.93 for the solar metallicity is larger than that for the SN 1987A 7Li/11B=0.80 by 16 % in the inverted mass hierarchy case. We analyze contributions of respective reactions as well as abundance evolution, and clarify the $\nu$-process of 7Li and 11B.

We discuss angular distributions of elastic, inelastic, and break-up cross-sections for the $$^{11}\hbox {Be} + ^{197}\hbox {Au}$$ system, measured at energies below and around the Coulomb barrier. To this end, we employ Coulomb dipole excitations and a long-range nuclear (LRN) potential in order to account for long-range effects of the halo nuclear system and break-up effects of the weakly bound structure. We then analyze recent experimental data, comprising three channels, viz., elastic, inelastic, and break-up cross-sections, at $$E_{\text {c.m.}}=29.6\hbox { MeV}$$ and $$E_{\text {c.m.}}=37.1\hbox { MeV}$$. From the parameter sets extracted using a $$\chi ^{2}$$ analysis, we successfully reproduce the experimental angular distributions of the elastic, inelastic, and break-up cross-sections for the $$^{11}\hbox {Be+}^{197}\hbox {Au}$$ system simultaneously. Finally, we discuss the necessity of the LRN potential around the Coulomb barrier from a detailed analysis of the experimental data.

The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24\,m short baseline at J-PARC. The JSNS$^{2}$ inner detector is filled with 17 tons of gadolinium-loaded liquid scintillator (LS) and both the intermediate $\gamma$-catcher and the optically separated outer veto are filled with un-loaded LS. Optical photons from scintillation are observed by 120 Photomultiplier Tubes (PMTs). A total of 130 PMTs for the JSNS2 experiment were both donated by other experiments and purchased from Hamamatsu. Donated PMTs were purchased around 10 years ago, therefore JSNS$^{2}$ did pre-calibration of the PMTs including the purchased PMTs. 123 PMTs demonstrated acceptable performance for the JSNS$^{2}$ experiment, and 120 PMTs were installed in the detector.

We suggest a hybrid model for neutron star matter to discuss the hyperon puzzle inherent in the 2.0 M$_{\odot}$ of the neutron star. For the nucleon–nucleon ($NN$) interaction, we employ the Skyrme–Hartree–Fock approach based on various Skyrme interaction parameter sets, and take the Brueckner–Hartree–Fock approach for the interactions related to hyperons. For the many-body interactions including hyperons, we make use of the multi-pomeron-exchange model, whose parameters have been adjusted to the data deduced from various hypernuclei properties. For clear understanding of the physics in the hybrid model, we discuss fractional functions of related particles, symmetry energies, and chemical potentials in dense matter. Finally, we investigate the equations of state and mass–radius relation of neutron stars, and show that the hybrid model can properly describe the 2.0 M$_{\odot}$ neutron star mass data with the many-body interaction employed in the hybrid model. Recent tidal deformability data from the gravitational wave observation are also compared to our calculations, especially in terms of the neutron skin of $^{208}$Pb and nuclear incompressibility.

We discuss the role of deformation of the target nucleus in the fusion reaction of the $^{15}$C + $^{232}$Th system at energies around the Coulomb barrier, for which $^{15}$C is a well-known one-neutron halo nucleus. To this end, we construct the potential between $^{15}$C and $^{232}$Th with the double folding procedure, assuming that the projectile nucleus is composed of the core nucleus, $^{14}$C, and a valance neutron. By taking into account the halo nature of the projectile nucleus as well as the deformation of the target nucleus, we simultaneously reproduce the fusion cross sections for the $^{14}$C + $^{232}$Th and the $^{15}$C + $^{232}$Th systems. Our calculation indicates that the net effect of the breakup and the transfer channels is small for this system., Comment: 7 pages, 5 figures

We study the v\bar v\-pair emission from electrons and protons in a relativistic quantum approach. In this work we calculate the luminosity of the v\bar v\-pairs emitted from neutron-star-matter with a strong magnetic field, and find that this luminosity is much larger than that in the modified Urca process. The v\bar v\-pair emission processes in strong magnetic fields significantly contribute to the cooling of the magnetars.

We calculate Galactic Chemical Evolution (GCE) of Mo and Ru by taking into account the contribution from $\nu p$-process nucleosynthesis. We estimate yields of $p$-nuclei such as $^{92,94}\mathrm{Mo}$ and $^{96,98}\mathrm{Ru}$ through the $\nu p$-process in various supernova (SN) progenitors based upon recent models. In particular, the $\nu p$-process in energetic hypernovae produces a large amount of $p$-nuclei compared to the yield in ordinary core-collapse SNe. Because of this the abundances of $^{92,94}\mathrm{Mo}$ and $^{96,98}\mathrm{Ru}$ in the Galaxy are significantly enhanced at [Fe/H]=0 by the $\nu p$-process. We find that the $\nu p$-process in hypernovae is the main contributor to the elemental abundance of $^{92}$Mo at low metallicity [Fe/H$], Comment: 15 pages, 5 figures, accepted for publication in ApJ

The short-lived unstable isotopes with half-lives of 0.1–10 My have been used as nuclear cosmochronometers to evaluate from an astrophysical event such as supernova (SN) explosion or AGB s-process to the solar system formation. We have proposed shorted-lived radioisotopes of 92Nb and 98Tc as the nuclear cosmochronometers for supernova neutrino-process

Using the optical model (OM) potential, we perform simultaneous χ2 analysis of the elastic scattering and the breakup reaction data for 11Li + 208Pb system. We introduce Coulomb dipole excitation (CDE) and long-range nuclear (LRN) potentials to consider effects of long range interaction. By the simultaneous χ2 analysis, we obtain a variety of the parameter set with a large diffuseness parameter which is inferred by two valence neutrons of 11Li located in two different orbits moving into a wide region. From the extracted best parameter set, finally, we calculate the breakup, total fusion, and total reaction cross sections. The total reaction and the breakup reaction cross sections obtained from our present work well reproduced experimental data within 5% and 10%, respectively, whereas the total fusion cross sections overestimate experimental data. Detailed discussions regarding the disagreement with the fusion data are also addressed.

We discuss the role of two-neutron transfer processes in the fusion reaction of the $^{9,11}$Li + $^{208}$Pb systems. We first analyze the $^{9}$Li + $^{208}$Pb reaction by taking into account the coupling to the $^{7}$Li + $^{210}$Pb channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in $^{210}$Pb and solve the coupled-channels equations with the two channels. By adjusting the coupling strength and the effective $Q$-value, we successfully reproduce the experimental fusion cross sections for this system. We then analyze the $^{11}$Li + $^{208}$Pb reaction in a similar manner, that is, by taking into account three effective channels with $^{11}$Li + $^{208}$Pb, $^{9}$Li + $^{210}$Pb, and $^{7}$Li + $^{212}$Pb partitions. In order to take into account the halo structure of the $^{11}$Li nucleus, we construct the potential between $^{11}$Li and $^{208}$Pb with a double folding procedure, while we employ a Wood-Saxon type potential with the global Aky\"uz-Winther parameters for the other channels. Our calculation indicates that the multiple two-neutron transfer process plays a crucial role in the $^{11}$Li + $^{208}$Pb fusion reaction at energies around the Coulomb barrier.

We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar., Comment: 14 pages, 3 figures

We calculate the total fusion cross sections for the 6He + 209Bi, 6Li + 209Bi,9Be + 208Pb, 10Be + 209Bi, and 11Li + 208Pb systems by using a coupled-channel (CC) method and compare the results with the experimental data. In the CC approach for the total fusion cross sections, we exploit a globally determined Wood-Saxon potential with Akyuz-Winther parameters and couplings of the ground state to the low-lying excited states in the projectile and the target nuclei. The total fusion cross sections obtained with the CC are compared with those obtained without the CC couplings. The latter approach is tantamount to a one-dimensional barrier penetration model. Finally, our approach is applied to understand new data for the 11Li+208Pb system. Possible ambiguities inherent in those approaches are discussed in detail for further applications to the fusion system of halo and/or neutron-rich nuclei.

The roles of strange axial form factor and axial mass for both neutral-current and charged-current reactions are investigated in the quasi-elastic neutrino-nucleus scattering within a relativistic single-particle model. The calculation is performed for various target nuclei like $^{12}\mathrm{C}$, $^{40}\mathrm{Ca}$, $^{56}\mathrm{Fe}$, and $^{208}\mathrm{Pb}$ at the incident neutrino (antineutrino) energies of 1.0 and 2.0 GeV. Then we discuss the dependence of differential cross section on the role of axial mass and strange axial form factor with different target nuclei on both neutral-current and charged-current reactions. Finally we compare our results with the MiniBooNE, T2K, and $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ experimental data for the double-differential cross section and the scaled total cross section.

We perform systematic calculations regarding the effects by Coulomb and/or spin-orbit (SO) interaction on like- and unlike-pairing correlations in $sd$-, $pf$-, and $sdgh$-shell $N=Z$ nuclei. The former two interactions are comprised in a deformed mean-field potential and the latter pairing correlations are treated by residual interactions in the mean field. We make use of two different pairing matrix elements (PMEs) for the residual interactions : constant and state-dependent Brueckner $G$ matrix. The constant PME may give rise to meaningful information on the pairing correlations under the Wigner spin-isospin SU(4) symmetry in the absence of the Coulomb and the SO interaction. The state-dependent Brueckner PME takes into account the nuclear medium effect based on a realistic nucleon-nucleon interaction. In this work, through the analyses of the Coulomb and the SO interaction effects on the pairing correlations, we discuss in detail the isoscalar pair condensation and the coexistence of the isoscalar and the isovector pairs in the unlike pairing of the $N=Z$ nuclei. Our results show that the Coulomb and the SO interaction as well as nuclear deformation affect the single-particle state evolution in a deformed mean field and, as a result, give significant impacts on the pairing correlations and the smearing of occupation probabilities near Fermi energy. In particular, the pairing gaps in the heavy nuclei are largely disturbed by the Coulomb interaction as well as the SO interaction.

We propose a correction of the standard Big Bang nucleosynthesis (BBN) scenario to resolve the primordial lithium problem by considering a possibility that the primordial plasma can deviate from the ideal state. In the standard BBN, the primordial plasma is assumed to be ideal, with particles and photons satisfying the Maxwell-Boltzmann and Planck distribution, respectively. We suggest that this assumption of the primordial plasma being ideal might oversimplify the early Universe and cause the lithium problem. We find that deviation of photon distribution from the Planck distribution, which is parameterised with the help of Tsallis statistics, can resolve the primordial lithium problem when the particle distributions of the primordial plasma still follow the MaxwellBoltzmann distribution. We discuss how the primordial plasma can be weakly non-ideal in this specific fashion and its effects on the cosmic evolution., Comment: 8 pages, 6 figures, version to appear in A&A

Taking into account the terrestrial experiments and the recent astrophysical observations of neutron stars and gravitational-wave signals, we impose restrictions on the equation of state (EoS) for isospin-asymmetric nuclear matter. Using the relativistic mean-field model with SU(3) flavor symmetry, we investigate the impacts of effective nucleon mass, nuclear incompressibility, and slope parameter of nuclear symmetry energy on the nuclear and neutron-star properties. It is found that the astrophysical information of massive neutron stars and tidal deformabilities as well as the nuclear experimental data plays an important role to restrict the EoS for neutron stars. Especially, the softness of the nuclear EoS due to the existence of hyperons in the core gives stringent constraints on those physical quantities. Furthermore, it is possible to put limits on the curvature parameter of nuclear symmetry energy by means of the nuclear and astrophysical calculations., Comment: 15 pages, 13 figures

Using the Lorentz-covariant decomposition of nucleon self-energies with relativistic mean-field approximation, we study the effect of Fock terms on the density dependence of nuclear symmetry energy, E sym. It is found that the Fock contribution suppresses the potential part of E sym at higher densities, and the constraint from the heavy-ion collision data is in favor of the present result including exchange terms with the cutoff parameters given by the CD-Bonn potential. In addition, not only the isovector-vector (ρ) meson but also the isoscalar (σ, ω) and π mesons give influence on the potential part of E sym through the exchange diagram.

We investigate the pairing correlations on N = Z nuclei. In particular, the isoscalar (IS) pairing mode in neutron-proton (np) pairing is discussed in detail because the IS np pairing is closely related to the tensor force in the nucleon-nucleon interaction. Recent experiments demonstrated that the IS pairing might be enhanced from the M1 spin strength distribution data and deuteron, which is a consequence of the IS pairing, can be detected in 16O(p,p’d)14N reaction. The present study illustrates that the IS np pairing can be condensed not only in S=0, L = odd states but also in S=1, L=even states. The former is usually treated as T=0 np pairing. The latter is associated with deuteron and has not been fully treated in the BCS theory for the nuclear structure. In particular, the latter np pairing can be ejected as deuteron from the energetic probes in the experiments. Detailed analyses of the np pairing are performed mainly on 16O and extended to other N = Z nuclei.

We study the ν ν ¯ -pair synchrotron emission from electrons and protons in a relativistic quantum approach. This process occurs only in the presence of a strong magnetic field, and it is considered to be one of effective processes for neutron star cooling. In this work we calculate the luminosity of the ν ν ¯ -pairs emitted from neutron-star-matter with a magnetic field of about 1015 G. We find that the energy loss is much larger than that of the modified Urca process. The ν ν ¯ -pair emission processes in strong magnetic fields is expected to contribute significantly to the cooling of the magnetars.

Using the Lorentz-covariant decomposition of nucleon self-energies based on the Hugenholtz–Van Hove theorem, we study the effect of Fock terms on the nuclear symmetry energy and its slope parameter within relativistic Hartree-Fock approximation. It is found that the exchange contribution suppresses the nuclear symmetry energy and prevents the slope parameter from increasing monotonically at high densities. Furthermore, not only the isovector-vector (ρ) meson but also the isoscalar mesons (σ,ω) and pion give significant influence on the potential term of nuclear symmetry energy through the exchange diagrams. Keywords: Asymmetric nuclear matter, Nuclear symmetry energy, Relativistic Hartree-Fock approximation

The isotope $^{98}\mathrm{Tc}$ decays to $^{98}\mathrm{Ru}$ with a half-life of $4.2\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }\text{ }\mathrm{yr}$ and could have been present in the early Solar System. In this Letter, we report on the first calculations of the production of $^{98}\mathrm{Tc}$ by neutrino-induced reactions in core-collapse supernovae (the $\ensuremath{\nu}$ process). Our predicted $^{98}\mathrm{Tc}$ abundance at the time of solar system formation is not much lower than the current measured upper limit raising the possibility for its detection in the not too distant future. We show that, if the initial abundance were to be precisely measured, the $^{98}\mathrm{Tc}$ nuclear cosmochronometer could be used to evaluate a much more precise value of the duration time from the last core-collapse supernova to the formation of the solar system. Moreover, a unique and novel feature of the $^{98}\mathrm{Tc}$ $\ensuremath{\nu}$-process nucleosynthesis is the large contribution ($\ensuremath{\sim}20%$) from charged current reactions with electron antineutrinos. This means that $^{98}\mathrm{Tc}$ becomes a unique new $\ensuremath{\nu}$-process probe of the temperature of the electron antineutrinos.

We investigated neutron-proton pairing correlations effects on the shell evolution of ground-state energies by the deformation for $N=Z$ nuclei in $pf$ shell, such as $^{44}\mathrm{Ti}$, $^{48}\mathrm{Cr}$, $^{52}\mathrm{Fe}$, $^{64}\mathrm{Ge}$, $^{68}\mathrm{Se}$, $^{72}\mathrm{Kr}$, and $^{76}\mathrm{Sr}$. We started from a simple shell-filling model constructed by a deformed Woods-Saxon potential with ${\ensuremath{\beta}}_{2}$ deformation, and included pairing correlations in the residual interaction, which give rise to smearing of the Fermi surface revealing interesting evolution of the Fermi energy along the shell evolution. In this work, like-pairing and unlike-pairing correlations decomposed as isovector $T=1$ and isoscalar $T=0$ components are explicitly taken into account. Finally, we estimate ground-state energies comprising the mean-field energy, the pairing energy, and the self-energy due to the pairing correlations, in terms of the deformation. The enhanced $T=0$ pairing interaction supports oblate deformations for $^{72}\mathrm{Kr}$ and $^{68}\mathrm{Se}$, whose features are different from other $pf$-shell $N=Z$ nuclei considered in this work.

Recently, a tetraquark mixing framework has been proposed for light mesons and applied more or less successfully to the isovector resonances, $a_0(980), a_0(1450)$, as well as to the isodoublet resonances, $K^*_0(800), K^*_0(1430)$. In this work, we present a more extensive view on the mixing framework and extend this to the isoscalar resonances, $f_0 (500)$, $f_0(980)$, $f_0 (1370)$, $f_0(1500)$. Tetraquarks in this framework can have two spin configurations containing either spin-0 diquark or spin-1 diquark and each configuration forms a nonet in flavor space. The two spin configurations are found to mix strongly through the color-spin interactions. Their mixtures, which diagonalize the hyperfine masses, can generate the physical resonances constituting the two nonets, which, in fact, coincide roughly with the experimental observation. We identify that $f_0 (500)$, $f_0(980)$ are the isoscalar members in the light nonet, and $f_0 (1370)$, $f_0(1500)$ are the similar members in the heavy nonet. This means that the spin configuration mixing, as it relates the corresponding members in the two nonets, can generate $f_0 (500), f_0 (1370)$ among the members in light mass, and $f_0(980), f_0(1500)$ in heavy mass. The complication arises because the isoscalar members of each nonet are subject to an additional flavor mixing known as OZI rule so that $f_0 (500), f_0 (980)$, and similarly $f_0 (1370), f_0 (1500)$, are the mixture of two isoscalar members belonging to an octet and a singlet in SU$_f$(3). The tetraquark mixing framework including the flavor mixing is tested for the isoscalar resonances in terms of the mass splitting and the fall-apart decay modes., Comment: 16 pages, 2 figures, slightly modified, 2 references added