Using the recently published data from the BONuS (Barely Off-shell Nucleon Structure) experiment at Jefferson Lab, which utilized a spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron $F_2$ structure function. The data are used to reconstruct the lowest few ($N=2$, 4, and 6) moments of $F_2$ in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark-hadron duality holds locally for the neutron in the second and third resonance regions down to $Q^2\approx 1{\mathrm{GeV}}^2$, with violations possibly up to 20% observed in the first resonance region.

Nucleon self-energies and interaction potentials in supernova (SN) matter, which are known to have an important effect on nucleosynthesis conditions in SN ejecta are investigated. Corresponding weak charged-current interaction rates with unbound nucleons that are consistent with existing SN equations of state (EOSs) are specified. The nucleon self-energies are made available online as electronic tables. The discussion is mostly restricted to relativistic mean-field models. In the first part of the article, the generic properties of this class of models at finite temperature and asymmetry are studied. It is found that the quadratic expansion of the EOS in terms of asymmetry works reasonably well at finite temperatures and deviations originate mostly from the kinetic part. The interaction part of the symmetry energy is found to be almost temperature independent. At low densities, the account of realistic nucleon masses requires the introduction of a linear term in the expansion. Finally, it is shown that the important neutron-to-proton potential difference is given approximately by the asymmetry of the system and the interaction part of the zero-temperature symmetry energy. The results of different interactions are then compared with constraints from nuclear experiments and thereby the possible range of the potential difference is limited. In the second part, for a certain class of SN EOS models, the formation of nuclei is considered. Only moderate modifications are found for the self-energies of unbound nucleons that enter the weak charged-current interaction rates. This is because in the present approach the binding energies of bound states do not contribute to the single-particle energies of unbound nucleons.

We study the effects of strangeness on the quark sector of a hybrid-star equation of state. Since the model we use to describe quarks is the same as the one we use to describe hadrons, we can also study the effects of strangeness on the chiral symmetry restoration and deconfinement phase transitions (first order or crossover). Finally, we analyze the combined effects of hyperons and quarks on global properties of hybrid stars such as mass, radius, and cooling profiles. It is found that a large amount of strangeness in the core is related to the generation of twin-star solutions, which can have the same mass as the lower or zero strangeness counterpart, but with smaller radii.

The equation of state of neutron star matter is calculated within the lowest order constrained variational (LOCV) method using different two-body interactions and an Urbana type three-body force. The core of the neutron star is modelled by $\beta$-stable matter. The corresponding neutron star mass-radius relations are presented and the effect of using a three-body interaction on the maximum gravitational mass of the star is also discussed. It is shown that including the three-body force generally increases the maximum gravitational mass.

The quasi-SU(3) sequence of the positive parity $\nu g_{9/2},d_{5/2},s_{1/2}$ orbitals above the $N=40$ shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe $\left(Z=26\right)$ and Cr $\left(Z=24\right)$ isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of ${}^{68}\mathrm{Ni} (Z=28,N=40)$ through the ${}^{66}\mathrm{Ni}(d,p){}^{67}\mathrm{Ni}$ one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball $\gamma$-array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-$\mu \mathrm{s}$ isomer at 1007 keV in ${}^{67}\mathrm{Ni}$. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the $\nu g_{9/2}$ (1007 keV) and $\nu d_{5/2}$ (2207 keV and 3277 keV) positive-parity neutron states and negative parity $\left(\nu pf\right)$ states have been observed at low excitation energy. The extracted relative spectroscopic factors, based on a distorted-wave Born approximation analysis, show that the $\nu d_{5/2}$ single-particle strength is mostly split over these two excited states. The results are also compared to the distribution of the proton single-particle strength in the ${}^{90}\mathrm{Zr}$ region $(Z=40,N=50)$.

In this work, based on one updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model in which the Skyrme-like (parabolic) isospin- and momentum-dependent interaction is included, the effect of the neutron-proton effective mass splitting (NPEMS) on flows in heavy-ion collisions at the Fermi-energy domain (between 40 and 100 MeV/nucleon) is focused. Using various Skyrme interactions (all exhibiting similar values of isoscalar incompressibility but very different NPEMS), both rapidity- and transverse-momentum-dependent directed and elliptic flows of free neutrons and protons are calculated. Our calculations show that the effect of NPEMS on the flows of free nucleons is more obvious at $E_{\mathrm{lab}}=100\mathrm{MeV}/\mathrm{nucleon}$ than at $40 \mathrm{MeV}/\mathrm{nucleon}$. At $E_{\mathrm{lab}}=100\mathrm{MeV}/\mathrm{nucleon}$, the directed flows of both neutrons and protons are easily affected by the NPEMS, while the elliptic flow of protons is not very sensitive to the NPEMS at both energies. It is suggested that the directed flow is better than the elliptic flow for probing the NPEMS.

A linear Boltzmann transport model within perturbative QCD is developed for the study of parton propagation inside the quark-gluon plasma. Both leading partons and thermal recoil partons are tracked so that one can also study jet-induced medium excitations. In this study, we implement the complete set of elastic parton scattering processes and investigate elastic parton energy loss, transverse momentum broadening, and their nontrivial energy and length dependence. We further investigate medium modifications of the jet shape and fragmentation functions of reconstructed jets. Contributions from thermal recoil partons are found to have significant influences on jet shape, fragmentation functions, and angular distribution of reconstructed jets.

We analyze in detail the possibility of Bose-Einstein condensation of pions produced in heavy-ion collisions at the beam energy $\sqrt{s_{NN}}=2.76$ TeV. Our approach is based on the chemical nonequilibrium thermal model of hadron production which has been generalized to include separately the contribution from the local zero-momentum state. In order to study both the hadronic multiplicities and the transverse-momentum spectra, we use the Cracow freeze-out model which parameterizes the flow and space-time geometry of the system at freeze-out in a very economic way. Our analysis indicates that about 5% of all pions may form the Bose-Einstein condensate.

A potential explanation [U. D. Jentschura, Phys. Rev. A 88, 062514 (2013)] of the proton radius puzzle originating from the nonperturbative lepton-pair content of the proton is studied. Well-defined quantities that depend on this lepton-pair content are evaluated. Each is found to be of the order of $10{\left(\frac{\alpha }{\pi }\right)}^2$, so that such a lepton-pair content does exist in the proton. However, I argue that this relatively large result and general features of loop diagrams rule out the possibility of lepton-pair content as an explanation of the proton radius puzzle. The contributions of a class of potential explanations of the proton radius puzzle (for which the dependence on the $\mu p$ relative distance is as contact interaction) are shown to be increase very rapidly with atomic number.

A quartet is a tightly bound cluster of two protons and two neutrons, similar to the $\alpha$ particle but occasionally with nonzero spin and/or isospin. If the interaction between two quartets is weak in given states, such states are concluded to be well represented by a quartet structure. In this paper, we study the quartet structure of eight valence nucleons in two cases. The first is a single $j$ shell, demonstrating that the so-called stretch scheme [M. Danos and V. Gillet, Phys. Rev. Lett. 17, 703 (1966)] is very good for low-spin states with a quadruple-quadruple interaction, and is reasonably good under realistic interactions. The second case is the ground state of ${}^{92}\mathrm{Pd}$ in the $p_{1/2}{p}_{3/2}{f}_{5/2}{g}_{9/2}$ shell with the JUN45 effective interaction. We show that the quartet correlation is essential in the ground state of ${}^{92}\mathrm{Pd}$.

In this paper we study low-lying states of atomic nuclei with random interactions, within the framework of the nuclear shell model. The distributions of $R_6$ versus $R_4$ (where $R_I\equiv E_{I_1^{+}}/E_{2_1^{+}}$), empirical proton-neutron interaction, and charge radius are investigated by using a two-body random ensemble. The Mallmann plot exhibits statistical correlations between $R_6$ and $R_4$. The proton-neutron interaction between the last proton and the last neutron in even-$A$ nuclei is found to be stronger than that in odd-$A$ nuclei, and that in $N=Z$ nuclei is even stronger. Simple relations of nuclear charge radii for neighboring nuclei are found to survive remarkably for the random ensemble.

We express the transport coefficients appearing in the second-order evolution equations for bulk viscous pressure and shear stress tensor using Bose-Einstein, Boltzmann, and Fermi-Dirac statistics for the equilibrium distribution function and Grad's 14-moment approximation as well as the method of Chapman-Enskog expansion for the nonequilibrium part. Focusing on the case of transversally homogeneous and boost-invariant longitudinal expansion of the viscous medium, we compare the results obtained using the above methods with those obtained from the exact solution of the massive 0+$1d$ relativistic Boltzmann equation in the relaxation-time approximation. We show that compared to the 14-moment approximation, the hydrodynamic transport coefficients obtained by employing the Chapman-Enskog method lead to better agreement with the exact solution of the relativistic Boltzmann equation.

In this article we study the dynamics of a first-order phase transition from nucleonic to quark matter in neutron stars. Using standard equations of state for these two phases we find the density range where such a transition is possible. Then we study the transformation of the star assuming that the quark core is formed via a spherical shock wave. The thermodynamical conditions in the quark core are found from the conservation laws across the transition region. Their dependence on the density and velocity of the incoming nuclear matter are studied. It is found that the shock is especially violent in the beginning of the conversion process when the velocity of the in-falling matter is especially high. As the shock propagates further from the center, the front velocity first increases and reaches a maximum value when the incoming velocity is around $0.2$. Finally, the front velocity quickly goes to zero when incoming matter velocity approaches zero. We have shown that the density and pressure jumps are especially large in the beginning of the transition process. Such a shocklike phase transition in the compact star can manifest a neutrino burst and gravitational waves.

The electric quadrupole transitions between $0^{+},2^{+}$, and $4^{+}$ states in ${}^{12}\mathrm{C}$ are investigated in a $3\alpha$ model. The three-body wave functions are obtained by means of the hyperspherical adiabatic expansion method, and the continuum is discretized by imposing a box boundary condition. Corresponding expressions for the continuum three-body $\left(3\alpha \right)$ bremsstrahlung and photon dissociation cross sections are derived and computed for two different $\alpha \text{−}\alpha$ potentials. The available experimental energy dependence is reproduced and a series of other cross sections are predicted. The transition strengths are defined and derived from the cross sections, and compared to schematic rotational model predictions. The computed properties of the ${}^{12}\mathrm{C}$ resonances suggest that the two lowest bands are made, respectively, by the states $\{0_1^{+},2_1^{+},4_2^{+}\}$ and $\{0_2^{+},2_2^{+},4_1^{+}\}$. The transitions between the states in the first band are consistent with the rotational pattern corresponding to three alphas in an equilateral triangular structure. For the second band, the transitions are also consistent with a rotational pattern, but with the three alphas in an aligned arrangement.

The structure of the neutron-rich $\mathrm{\Lambda }$ hypernucleus, ${}_{\mathrm{\Lambda }}{}^7\mathrm{He}$ is studied within the framework of an $\alpha +\mathrm{\Lambda }+n+n$ four-body cluster model. We predict second $3/2^{+}$ and $5/2^{+}$ states, corresponding to a $0s\mathrm{\Lambda }$ coupled to the second $2^{+}$ state of ${}^6\mathrm{He}$, as narrow resonant states with widths of $\mathrm{\Gamma }\sim 1$ MeV to be at 0.03 and 0.07 MeV with respect to the $\alpha +\mathrm{\Lambda }+n+n$ threshold. From a separate estimate of the differential cross section for the ${}^7\mathrm{Li}(\gamma ,K^{+}){}_{\mathrm{\Lambda }}{}^7\mathrm{He}$ reaction, we suggest a possibility to observe these states at the Thomas Jefferson National Accelerator Facility (JLab) in the future. We also calculate the second $2^{+}$ state of ${}^6\mathrm{He}$ as a resonant state within the framework of an $\alpha +n+n$ three-body cluster model. Our result is $2.81$ MeV with $\mathrm{\Gamma }=4.63$ MeV with respect to the $\alpha +n+n$ threshold. This energy position is $\sim 1$ MeV higher, and with a much broader decay width, than the recent SPIRAL data. We suggest that an experiment at JLab to search for the second $3/2^{+}$ and $5/2^{+}$ states of ${}_{\mathrm{\Lambda }}{}^7\mathrm{He}$ would provide an opportunity to confirm the second $2^{+}$ state of the core nucleus ${}^6\mathrm{He}$.

Excited $0^{+}$ states in ${}^{160}\mathrm{Gd}$ have been examined with the $\left(n,n^{\prime }\gamma \right)$ reaction at incident neutron energies up to 2.8 MeV. Gamma-ray excitation functions and angular distribution measurements allow the confirmation of the existence of $0^{+}$ states at 1379.70 keV and 1558.30 keV, but we reject the assignments of additional previously suggested $0^{+}$ candidates. Limits on the level lifetimes of the observed $0^{+}$ states permit an evaluation of the collectivity of these states.

Elastic-scattering angular distributions were measured for the ${}^7\mathrm{Li}+{}^{159}\mathrm{Tb}$ system at various energies; namely, 24, 26, 28, 30, 35, 40, and 44 MeV. The optical-model analysis was performed to investigate the energy dependence of real and imaginary potentials, employing a Woods–Saxon form of potential. The dispersion-relation analysis were also carried out to check the consistency of real and imaginary parts of the potentials. The energy dependence of real and imaginary potentials does not follow the trend of conventional threshold anomaly but rather represents unusual behavior of the increase of imaginary part of the potential and corresponding decrease in real part of the potential near the Coulomb barrier energy. The effect of breakup coupling on elastic-scattering angular distributions was studied by a continuum-discretized coupled-channels (CDCC) calculation. The behavior of dynamic polarization potentials obtained due to the breakup coupling is discussed. The total reaction cross sections for the present and various other systems are also compared involving ${}^7\mathrm{Li}$ projectile on different target nuclei in the mass range $A=16$ to 232.

To test the relevance of the most common assumptions in the calculation of beta $\left(\beta \right)$ and neutrino $\left(\nu \right)$ spectra, a database of measured shape factors was created, containing 130 distinct transitions. Some analysis parameters were defined to characterize the quality of the calculated spectra. Results from this systematic comparison between theory and experiment are presented in detail. The ${\lambda }_k=1$ approximation for forbidden unique transitions is shown to be systematically worse than the correct calculation of the theoretical shape factors, where the energy dependence of the ${\lambda }_k$ parameters is included. Regarding forbidden nonunique transitions, the $\xi$ approximation is found to be valid for only about half of the first forbidden nonunique transitions and incorrect in all other cases. The criterion $2\xi /E_0\gg 1$ is proved to be insufficient in itself if $2\xi /E_0<100$.

The analytic quadrupole octupole axially symmetric model, which had successfully predicted ${}^{226}\mathrm{Ra}$ and ${}^{226}\mathrm{Th}$ as lying at the border between the regions of octupole deformation and octupole vibrations in the light actinides using an infinite well potential (AQOA-IW), is made applicable to a wider region of nuclei exhibiting octupole deformation, through the use of a Davidson potential, ${\beta }^2+{\beta }_0^4/{\beta }^2$ (AQOA-D). Analytic expressions for energy spectra and $B\left(E1\right),B\left(E2\right),B\left(E3\right)$ transition rates are derived. The spectra of ${}^{222\text{–}226}\mathrm{Ra}$ and ${}^{224,226}\mathrm{Th}$ are described in terms of the two parameters ${\varphi }_0$ (expressing the relative amount of octupole vs quadrupole deformation) and ${\beta }_0$ (the position of the minimum of the Davidson potential), while the recently determined $B\left(EL\right)$ transition rates of ${}^{224}\mathrm{Ra}$, presenting stable octupole deformation, are successfully reproduced. A procedure for gradually determining the parameters appearing in the $B\left(EL\right)$ transitions from a minimum set of data, thus increasing the predictive power of the model, is outlined.