We present a modified color screening model for $J/\psi$ suppression in the quark-gluon plasma (QGP) using the quasiparticle model (QPM) as the equation of state (EOS). Other theoretical ingredients incorporated in the model are feed-down from higher resonances, namely, ${\chi }_c$, and $\psi {}^{\prime }$, dilated formation time for quarkonia, and viscous effects of the QGP medium. By assuming further that the QGP is expanding with Bjorken's hydrodynamical expansion, the present model is used to analyze the centrality dependence of the $J/\psi$ suppression in the mid-rapidity region and compare it with the data obtained from Super Proton Synchrotron, Relativistic Heavy Ion Collider, and Large Hadron Collider experiments. We find that the centrality dependence of the data for the survival probability at all energies is well reproduced by our model. We further compare our model predictions with the results obtained from the bag model EOS for QGP which has usually been used earlier in all such calculations.

We present measured $J/\psi$ production rates in $d+\text{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV over broad ranges of transverse momentum ($p_T=0$–14 GeV/$c$) and rapidity ($-2.2<y<2.2$). We construct the nuclear-modification factor $R_{d\mathrm{Au}}$ for these kinematics and as a function of collision centrality (related to impact parameter for the $d+\mathrm{Au}$ collision). We find that the modification is largest for collisions with small impact parameters and observe a suppression ($R_{d\mathrm{Au}}<1$) for $p_T<4$ GeV/$c$ at positive rapidities. At negative rapidity we observe a suppression for $p_T<2$ GeV/$c$ then an enhancement ($R_{d\mathrm{Au}}>1$) for $p_T>2$ GeV/$c$. The observed enhancement at negative rapidity has implications for the interpretation of the observed modification in heavy-ion collisions at high $p_T$.

The $\beta$-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of ${}^{86}$Ge ($226\pm 21$ ms) was determined for the first time, while those of ${}^{84,85}$Ge and ${}^{84-87}$As were remeasured. The results are compared to theoretical predictions of the gross theory of $\beta$ decay, the finite-range droplet model, and the new calculations using the energy density functional DF3a with continuum quasiparticle random-phase approximation (CQRPA). We confirm the robustness and good predictive power of the latter model for nuclei near closed shells. These DF3a+CQRPA calculations were used recently to analyze $r$-process isobaric abundances.

The ${}^{147}$Ba nucleus has been studied in prompt $\gamma$-ray spectroscopy using the EUROGAM2 Ge array. Spin and parity of the ground state has been determined to be $5/2^{-}$. The unexpected, $5/2^{-}$ ground state results from interaction with other negative-parity configurations. A new ground-state band has been established in ${}^{147}$Ba and some previously reported levels have been arranged into a $3/2^{-}$ band, which may correspond to the $3/2^{-}$[532] configuration. The new spin assignments in ${}^{147}$Ba suggest that the theoretical predictions of static octupole deformation in the ground state of ${}^{147}$Ba may not be be valid. No candidates for parity doublets have been found in ${}^{147}$Ba. Instead, an octupole band built on the ground state has been proposed.

Background: Neutron-induced fission cross-section data are needed in various fields of applied and basic nuclear science. However, cross sections of short-lived nuclei are difficult to measure directly due to experimental constraints.

Purpose: The first experimental determination of the neutron-induced fission cross section of ${}^{239}$Np at nonthermal energies was performed. This minor actinide is the waiting point to ${}^{240}$Pu production in a nuclear reactor.

Method: The surrogate ratio method was employed to indirectly deduce the ${}^{239}\text{Np}(n,f)$ cross section. The surrogate reactions used were ${}^{236}\text{U}{(}^3\text{He},p)$ and ${}^{238}\text{U}{(}^3\text{He},p)$ with the reference cross section given by the well-known ${}^{237}\text{Np}(n,f)$ cross section. The ratio of observed fission reactions resulting from the two formed compound nuclei, ${}^{238}$Np and ${}^{240}$Np, was multiplied by the directly measured ${}^{237}\text{Np}(n,f)$ cross section to determine the ${}^{239}\text{Np}(n,f)$ cross section.

Results: The ${}^{239}\text{Np}(n,f)$ cross section was determined with an uncertainty ranging between 4$\%$ and 30$\%$ over the energy range of 0.5–20 MeV. The resulting cross section agrees closest with the JENDL-4.0 evaluation.

Conclusions: The measured cross section falls in between the existing evaluations, but it does not match any evaluation exactly (with JENDL-4.0 being the closest match); hence reactor codes relying on existing evaluations may under- or overestimate the amount of ${}^{240}$Pu produced during fuel burnup. The measurement helps constrain nuclear structure parameters used in the evaluations.

The angular distribution of proton-${}^9$C elastic scattering at 277–300 MeV/nucleon was measured with a newly designed recoil proton spectrometer. The angular distribution was analyzed using the relativistic impulse approximation. The root-mean-square matter radius of ${}^9$C was deduced to be $2.{43}_{-0.28}^{+0.55}$ fm with different two-parameter Fermi density distributions for protons and neutrons.

The extension of the Boltzmann-Uehling-Uhlenbeck model of nucleus-nucleus collision is presented. The isospin-dependent nucleon-nucleon cross sections are estimated using the proper volume extracted from the equation of state of the nuclear matter transformed into the form of the Van der Waals equation of state. The results of such simulations demonstrate the dependence on symmetry energy, which typically varies strongly from the results obtained using only the isospin-dependent mean field. The evolution of the $n/p$ multiplicity ratio with angle and kinetic energy, in combination with the elliptic flow of neutrons and protons, provides a suitable set of observables for determination of the density dependence of the symmetry energy. The model thus provides an environment for testing of equations of state that are used for various applications in nuclear physics and astrophysics.

Synthesis of element 120 in the ${}^{249}$Cf(${}^{50}$Ti,$xn$)${}^{299-x}$120 and ${}^{248}$Cm(${}^{54}$Cr,$xn$)${}^{302-x}$120 fusion evaporation reactions has been evaluated by means of a modified fusion by diffusion model. It is found that the fusion probability of the system ${}^{54}$Cr+${}^{248}$Cm is two times smaller than that of ${}^{50}$Ti+${}^{249}$Cf. On the other hand, the survival probability of the former is obviously greater than that of the latter. As a result, the loss in the fusion probability of the ${}^{54}$Cr+${}^{248}$Cm reaction is compensated by its gain in survival probability. The calculated maximum evaporation residue cross sections in the ${}^{249}$Cf(${}^{50}$Ti,3$n$)${}^{296}$120 and ${}^{248}$Cm(${}^{54}$Cr,4$n$)${}^{298}$120 reactions are quite close: 0.034 and 0.024 pb, respectively. Besides, as compared to the system ${}^{50}$Ti+${}^{249}$Cf, the ${}^{54}$Cr+${}^{248}$Cm combination has two advantages. First, ${}^{248}$Cm is much easier accumulate a sufficient amount for the target material than ${}^{249}$Cf. Second, the isotope ${}^{298}$120 has 178 neutrons, two neutrons more than the isotope ${}^{296}$120. Therefore, the ${}^{54}$Cr+${}^{248}$Cm combination should be one of most favorable candidates to produce superheavy element 120.

Two measurements of $\gamma$ rays from the slow-neutron capture reaction on a ${}^{101}\mathrm{Ru}$ target were performed at the PF1B cold-neutron facility and the DuMond GAMma Spectrometer GAMS5 of ILL Grenoble, to study in detail excitations in the transitional nucleus ${}^{102}\mathrm{Ru}$. A band structure on top of the $0_2^{+}$ level has been identified and its nature is discussed. Mixing between the $0_1^{+}$ and $0_2^{+}$ levels in Ru isotopes with $50<N<66$ neutrons and its role in the development of deformation in the ground state of the Ru nuclei have been studied.

Both isoscalar and isovector spin-dipole excitations of ${}^4$He are studied using realistic nuclear forces in the complex scaling method. The ground state of ${}^4$He and discretized continuum states with $J^{\pi }=0^{-},1^{-},2^{-}$ for $A=4$ nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non-energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of ${}^4$He.

In this paper we derive the analytical formulas of the number of spin-$I$ states (denoted as $D_I$) for three identical particles, in a unified form for both fermions and bosons. This is done by using $\overline{n}$ virtual bosons with spin $3/2$, where $\overline{n}$ equals $2j-2$ if one studies fermions in a single-$j$ shell or $2l$ if one studies bosons with spin $l$. We first obtain a reduction rule from U(4) to O(3) for such virtual bosons and thereby derive the formulas of $D_I$. The formulas thus obtained are proved to be consistent with previous empirical formulas.

Background: Reliable cross sections for the neutrino-nucleus scattering off relevant nuclei for supernova neutrinos are essential for various applications in neutrino physics and astrophysics (e.g., supernova mechanisms). Studies of the nuclear responses for the stable molybdenum isotopes are of great interest for the planned MOON (Mo Observatory of Neutrinos) experiment.

Purpose: The purpose of the present work is, thus, to perform a detailed study of the charged-current nuclear responses to supernova neutrinos for the stable odd molybdenum isotopes. A special effort will be devoted to discuss in detail the structures of the most relevant final states in the corresponding proton-odd nucleus.

Method: The cross sections are computed by using the well-established framework for studies of semileptonic processes in nuclei developed by Donnelly and Walecka. The nuclear wave functions of the initial and the final nuclear states are computed by using the microscopic quasiparticle-phonon model. The nuclear responses to supernova neutrinos are subsequently estimated by folding the cross sections with realistic energy profiles for the incoming neutrinos.

Results: We present results for the cross sections of the charged-current neutrino and antineutrino scatterings off ${}^{95}\text{Mo}$ and ${}^{97}\text{Mo}$. Nuclear responses to supernova neutrinos (both nonoscillating and oscillating ones) are also given. The inclusion of neutrino oscillations enhances significantly the neutrino and antineutrino cross sections.

Conclusions: We have found that the most important transitions are the Gamow-Teller–like ones which are mediated by the $1^{+}$ multipole. Furthermore, the three-quasiparticle degrees of freedom are essential in order to describe quantitatively the neutrino-nucleus scattering off odd open-shell nuclei.

This paper studies baryons and baryonic matter in the combined large $N_c$ and heavy quark mass limits of QCD in 1+1 dimension. This regime allows for a simple physical picture, which is computationally tractable. In this nonrelativistic limit, baryons are composed of $N_c$ quarks that interact, at leading order in $N_c$, through a color Coulomb potential. Using variational techniques, single baryon masses and interaction energies of low-density baryon crystal are calculated. The single baryon calculations are very accurate and can be used as a crosscheck to the general numerical approach based on Hamiltonian methods for baryons and baryonic matter in 1+1 dimension for arbitrary quark mass recently proposed by Bringoltz, which is based on a lattice in a finite box. It is noteworthy that the Bringoltz method differs from a previous approach developed by Salcedo et al. in its treatment of an effect due to the finite box size with periodic boundary conditions—namely, the existence of gauge configurations which wind around the box. As these are finite volume effects, one might expect them to be small for boxes that are large enough so that the baryon density approaches zero to high accuracy at the edges of the box. However, the effects of these windings appear to be quite large even in such boxes. The large mass infinite volume calculations performed here are consistent with the results of numerical calculations using the Bringoltz approach and confirm the importance of gauge fields that wrap around for finite systems. The calculation of the baryon crystal interaction energy requires the assumption that at low-densities the ground state is composed of individual baryons, each in color-singlet states, with wave functions orthogonal to one another. While plausible, this assumption is somewhat ad hoc in that one can construct configurations in which the entire state is color-singlet but cannot be broken into individual color-singlet baryons. However, the interaction energy of low-density baryon crystals calculated with this assumption is consistent with numerical results based on Bringoltz's approach. This suggests that the assumptions regarding the color structure is justified in 1+1 dimension. This is useful, as it supports a similar assumption that was made in 3+1 dimensions, where there is no alternative means of calculation.

Guided by the relativistic local density approximation, we explore a phenomenological formula for the coupling strength of the Coulomb field to effectively take into account the Coulomb exchange term in the relativistic Hartree approximation. Its validity for finite nuclei is examined by comparing with the exact treatment of the Coulomb exchange energies in the relativistic Hartree-Fock-Bogoliubov approach. It is found that the exact Coulomb exchange energies can be reproduced by employing the phenomenological formula with the relative deviations less than $1\%$ for semimagic Ca, Ni, Sn, and Pb isotopes. Furthermore, we check the applicability of the phenomenological formula for the effective interactions in the relativistic Hartree approach by investigating the binding-energy differences of mirror nuclei.

Background: Excited-state transitions in double-$\beta$ decays are a powerful tool to validate and tune calculations of nuclear matrix elements.

Purpose: The experimental lower half-life limits for double-$\beta$ decays of ${}^{110}\mathrm{Pd}$ and ${}^{102}\mathrm{Pd}$ into the excited $2_1^{+}$ and $0_1^{+}$ states are improved. Furthermore, the first limits of transitions into the $2_2^{+}$, $0_2^{+}$, and $2_3^{+}$ states are published for ${}^{110}\mathrm{Pd}$ as well as a first limit for the $2_2^{+}$ state transition in ${}^{102}\mathrm{Pd}$.

Methods: The Pd sample was measured with two HPGe detectors in sandwich configuration in the HADES underground laboratory during 44.77 d of lifetime. The analysis was performed with the frequentist Feldman-Cousins method.

Results: Lower half-life limits of $1.98\times {10}^{20}$ and $1.72\times {10}^{20}$ yr (95$\%$ CL) were found for the first $0^{+}$ and $2^{+}$ excited states in ${}^{110}\mathrm{Pd}$, respectively. This is an improvement by more than a factor of 3 with respect to previous measurements. In ${}^{102}\mathrm{Pd}$, the lower half-life limit could be improved to $5.95\times {10}^{18}$ yr (95$\%$ CL) for the first $0^{+}$ excited state. Furthermore, first experimental lower half-life limits were found for all possible excited states in the ${}^{110}\mathrm{Pd}$ and ${}^{102}\mathrm{Pd}$ systems.

Conclusions: Previous half-life limits were improved and experimental results were obtained for all theoretical calculations of palladium double-$\beta$ decays into excited states.

An exclusive measurement of the excitation function for the $dd\to {}^3\mathrm{He}p{\pi }^{-}$ reaction was performed at the Cooler Synchrotron COSY-Jülich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/$c$ crossing the kinematic threshold for the $\eta$-meson production in the $dd\to {}^4\mathrm{He}\eta$ reaction at 2.336 GeV/$c$. The corresponding excess energy with respect to the ${}^4$He-$\eta$ system varied from $-$51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the $dd\to {}^3\mathrm{He}n$ reaction. The shape of the excitation function for the $dd\to {}^3\mathrm{He}p{\pi }^{-}$ reaction was examined. No signal of the ${}^4$He-$\eta$ bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process $dd\to {({}^4\mathrm{He}-\eta )}_{\mathrm{bound}}\to {}^3\mathrm{He}p{\pi }^{-}$ was determined on the 90$\%$ confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively.

We present the first results for the neutron matter equation of state (EOS) using nucleon-nucleon and three-nucleon chiral effective field theory interactions that are consistently evolved in the framework of the similarity renormalization group (SRG). The dependence of the EOS on the SRG resolution scale is greatly reduced when induced three-nucleon forces (3NF) are included, and the residual variation, which in part is from missing induced four-body interactions, is comparable to estimated many-body perturbation theory truncation errors. The relative growth with decreasing resolution of the 3NF contributions to the energy per neutron is of natural size, but it accelerates at the lowest resolutions where strong renormalization of the long-range 3NF matrix elements is also observed.

The electron capture decay branch of ${}^{116}$In has been measured to be $[2.46\pm 0.44(\mathrm{stat}.)\pm 0.39(\mathrm{syst}.)]\times {10}^{-4}$ using Penning trap-assisted decay spectroscopy. The corresponding Gamow-Teller transition strength is shown to be compatible with the most recent value extracted from the $(p,n)$ charge-exchange reaction, providing a resolution to longstanding discrepancies. This transition can now be used as a reliable benchmark for nuclear-structure calculations of the matrix element for the neutrinoless double-$\beta$ decay of ${}^{116}$Cd and other nuclides.

We have performed shell-model calculations for the two one-valence-neutron isotones ${}^{135}$Te and ${}^{137}$Xe and the two one-valence-proton isotopes ${}^{135,137}$Sb. The main aim of our study has been to investigate the evolution of single-particle states with increasing nucleon number. To this end, we have focused attention on the spectroscopic factors and the effective single-particle energies. In our calculations, we have employed a realistic low-momentum two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential that has already proved quite successful in describing the spectroscopic properties of nuclei in the ${}^{132}$Sn region. Comparison shows that our results reproduce very well the available experimental data. This gives confidence in the evolution of the single-particle states predicted by the present study.

The pairing correlation energy for two-nucleon configurations with the spin-parity and isospin of $J^{\pi }=0^{+}$, $T=1$ and $J^{\pi }=1^{+}$, $T=0$ are calculated with $T=1$ and $T=0$ pairing interactions, respectively. To this end, we consider the $\left(1f2p\right)$-shell-model space, including single-particle angular momenta of $l=3$ and $l=1$. It is pointed out that a two-body matrix element of the spin-triplet $T=0$ pairing is weakened substantially for the $1f$ orbits, even though the pairing strength is much larger than that for the spin-singlet $T=1$ pairing interaction. In contrast, the spin-triplet pairing correlations overcome the spin-singlet pairing correlations for the $2p$ configuration, for which the spin-orbit splitting is smaller than that for the $1f$ configurations, if the strength for the $T=0$ pairing is larger than that for the $T=1$ pairing by 50$\%$ or more. Using the Hartree-Fock wave functions, it is also pointed out that the mismatch of proton and neutron radial wave functions is at most a few percent level, even if the Fermi energies are largely different in the proton and neutron mean-field potentials. These results imply that the configuration with $J^{\pi }=0^{+}$, $T=1$ is likely in the ground state of odd-odd $pf$-shell nuclei even under the influence of the strong spin-triplet $T=0$ pairing, except at the middle of the $pf$ shell, in which the odd proton and neutron may occupy the $2p$ orbits. These results are consistent with the observed spin-parity $J^{\pi }=0^{+}$ for all odd-odd $N=Z$ $pf$-shell nuclei except for ${}_{29}^{58}$Cu, which has $J^{\pi }=1^{+}$. The magnetic moment of a $(J^{\pi },T)=(1^{+},0)$ state is also discussed in order to show a manifestation of the change of the shell-model scheme from $jj$ coupling to $LS$ coupling.