We study ground- and excited-state properties of all $sd$-shell nuclei with neutron and proton numbers $8\le N,Z\le 20$, based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties of nuclear matter. We focus on estimating the theoretical uncertainties due to variation of the resolution scale, the low-energy couplings, as well as from the many-body method. The experimental two-neutron and two-proton separation energies are reasonably well reproduced, with an uncertainty range of $\sim 5\text{MeV}$. The first excited $2^{+}$ energies also show overall agreement, with a more narrow uncertainty range of $\sim 500\text{keV}$. In most cases, this range is dominated by the uncertainties in the Hamiltonian.

We present the results from an experiment dedicated to search for quadrupole-collective isovector valence-shell excitations, states with so-called mixed proton-neutron symmetry (MSS), of ${}^{212}\mathrm{Po}$. This nucleus was studied in an $\alpha \text{-transfer}$ reaction. The lifetimes of two short-lived excited states, candidates for the one-phonon MSS, were determined by utilizing the Doppler shift attenuation method. The experimental results are in qualitative agreement with a simple $\text{single-}j$ shell model calculation, which, together with the observed lack of quadrupole collectivity, indicates that the isovector nature of low-lying states is a property of the leading single-particle valence shell configuration.

We report the measurement of cumulants ($C_n,n=1,...,4$) of the net-charge distributions measured within pseudorapidity ($\left|\eta \right|<0.35$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=7.7–200\mathrm{GeV}$ with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., $C_1/C_2, C_3/C_1$) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of $C_1/C_2$ and $C_3/C_1$ can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. The extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.

The isotope ${}^{135}\mathrm{Cs}$ is quoted as having a half-life of 2.3 Myr. However, there are three published values ranging from 1.8 to 3 Myr. This research reviews previous measurements and reports a new measurement of the half-life using newly developed accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICPMS) techniques along with $\beta$ and $\gamma$ radiometric analysis. The half-life was determined to be $(1.6\pm 0.6)\times {10}^6$ yr by AMS and $(1.3\pm 0.2)\times {10}^6$ yr by ICPMS with 95% confidence. The two values agree with each other but differ from the accepted value by $\sim 40\%$.

When the quark-gluon plasma emerges in the wake of a heavy-ion collision, a magnetic field created by the valence charges has already permeated the entire interaction region. Evolution of this “initial” field in the plasma is governed by the Maxwell equations in an electrically conducting medium. As the plasma expands, external valence charges induce a magnetic field that also contributes to the total magnetic field in the plasma. I solve the initial value problem describing these processes and argue that the initial magnetic field often dominates over the one induced by the valence charges. In particular, it grows approximately proportional to the collision energy, unlike the induced component, which is energy independent. As a result, the magnetic field has a significant phenomenological influence on the quark-gluon plasma at CERN Large Hadron Collider energies over its entire lifetime.

We study the possibility that partonic matter produced at an early stage of ultrarelativistic heavy-ion collisions is out of chemical equilibrium. It is assumed that initially this matter is mostly composed of gluons, but quarks and antiquarks are produced at later times. The dynamical evolution of partonic system is described by the Bjorken-like ideal hydrodynamics with a time-dependent quark fugacity. The results of this model are compared with those obtained by assuming the complete chemical equilibrium of partons already at the initial stage. It is shown that in a chemically nonequilibrium scenario the entropy gradually increases, and about 25% of the total final entropy is generated during the hydrodynamic evolution of deconfined matter. We argue that the (anti)quark suppression included in this approach may be responsible for reduced (anti)baryon-to-meson ratios observed in heavy-ion collisions at energies available at the CERN Large Hadron Collider.

Elliptic flow $\left(v_2\right)$ values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at $\sqrt{s_{NN}}=7.7–62.4$ GeV are presented for three centrality classes. The centrality dependence and the data at $\sqrt{s_{NN}}=14.5$ GeV are new. Except at the lowest beam energies, we observe a similar relative $v_2$ baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger $v_2$ for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.

Recently we have published a paper [Irgaziev, Phys. Rev. C 91, 024002 (2015)] where the $S$-matrix pole method (SMP), which is only valid for resonances, has been developed to derive an explicit expression for the asymptotic normalization coefficient (ANC) and is applied to the low-energy resonant states of $\mathrm{nucleon}+\alpha$ and $\alpha +{}^{12}\mathrm{C}$ systems. The SMP results are compared with the effective-range expansion method (EFE) results. In the present paper the SMP and EFE plus the Padé approximation are applied to study the excited $2^{+}$ resonant states of $\mathrm{Be}$. A contradiction is found between descriptions of the experimental phase shift data for $\alpha \alpha$ scattering and of the $\mathrm{Be}$ resonant energy for $2^{+}$ state. Using the EFE method, we also calculate the ANC for the $\mathrm{Be}$ ground $0^{+}$ state with a very small width. This ANC agrees well with the value calculated using the known analytical expression for narrow resonances. In addition, for the $\alpha +{}^{12}\mathrm{C}$ states $1^{-}$ and $3^{-}$ the SMP results are compared with the Padé approximation results. We find that the Padé approximation improves a resonance width description compared with the EFE results. The EFE method is also used to calculate the ANCs for the bound $\mathrm{O}$ ground $0^{+}$ state and for the excited $1^{-}$ and $2^{+}$ levels, which are situated near the threshold of $\alpha +{}^{12}\mathrm{C}$ channel.

In this paper, we study the role of the symmetry energy on the neutron-drip transition in both nonaccreting and accreting neutron stars, allowing for the presence of a strong magnetic field as in magnetars. The density, pressure, and composition at the neutron-drip threshold are determined using the recent set of the Brussels-Montreal microscopic nuclear mass models, which mainly differ in their predictions for the value of the symmetry energy $J$ and its slope $L$ in infinite homogeneous nuclear matter at saturation. Although some correlations between on the one hand the neutron-drip density, the pressure, the proton fraction, and on the other hand $J$ (or equivalently $L$) are found, these correlations are radically different in nonaccreting and accreting neutron stars. In particular, the neutron-drip density is found to increase with $L$ in the former case, but decreases in the latter case depending on the composition of ashes from x-ray bursts and superbursts. We have qualitatively explained these different behaviors using a simple mass formula. We have also shown that the details of the nuclear structure may play a more important role than the symmetry energy in accreting neutron-star crusts.

The $1i_{\frac{13}{2}}\to 1h_{\frac{9}{2}}\left(M2\right)$ and $3s_{\frac{1}{2}}\to 2f_{\frac{7}{2}}\left(E3\right)$ reduced proton transition probabilities in ${}_{83}{}^{209}\mathrm{Bi}$ have been determined from the direct half-life measurements of the ${\frac{13}{2}}_1^{+}$ and ${\frac{1}{2}}_1^{+}$ states using the Romanian array for $\gamma$-ray SPectroscopy in HEavy ion REactions (RoSPHERE). The ${\frac{13}{2}}_1^{+}$ and ${\frac{1}{2}}_1^{+}$ states were found to have $T_{\frac{1}{2}}=0.120\left(15\right)$ ns and $T_{\frac{1}{2}}=9.02\left(24\right)$ ns respectively. Angular distribution measurements were used to determine an $E3/M2$ mixing ratio of $\delta =-0.184\left(13\right)$ for the 1609 keV $\gamma$-ray transition deexciting the ${\frac{13}{2}}_1^{+}$ state. This value for $\delta$ was combined with the measured half-life to give reduced transition probabilities of $B(E3,{\frac{13}{2}}_1^{+}\to {\frac{9}{2}}_1^{-})=12\left(2\right)\times {10}^3{e}^2{\mathrm{fm}}^6$ and $B(M2,{\frac{13}{2}}_1^{+}\to {\frac{9}{2}}_1^{-})=38\left(5\right){\mu }_N^2{\mathrm{fm}}^2$. These values are in good agreement with calculations within the finite Fermi system. The extracted value of $B(E3,{\frac{1}{2}}_1^{+}\to {\frac{7}{2}}_1^{-})=6.3\left(2\right)\times {10}^3{e}^2{\mathrm{fm}}^6$ can be explained by a small ($\sim 6\%$) admixture in the wave function of the ${\frac{1}{2}}_1^{+}$ state.

The ${}^{241}\mathrm{Am}\left(n,2n\right){}^{240}\mathrm{Am}$ reaction cross section has been measured at four energies, 10.0, 10.4, 10.8, and 17.1 MeV, by means of the activation technique, relative to the ${}^{27}\mathrm{Al}\left(n,\alpha \right){}^{24}\mathrm{Na}$ reaction reference cross section. Quasi-monoenergetic neutron beams were produced via the ${}^2\mathrm{H}\left(d,n\right){}^3\mathrm{He}$ and the ${}^3\mathrm{H}\left(d,n\right){}^4\mathrm{He}$ reactions at the 5.5 MV Tandem T11/25 accelerator laboratory of NCSR “Demokritos”. The high purity ${}^{241}\mathrm{Am}$ targets were provided by JRC-IRMM, Geel, Belgium. The induced $\gamma$-ray activity of ${}^{240}\mathrm{Am}$ was measured with high-resolution high-purity germanium (HPGe) detectors. Auxiliary Monte Carlo simulations were performed with the mcnp code. The present results are in agreement with data obtained earlier and predictions obtained with the empire code.

The cross section for the ${}^{169}\text{Tm}\left(n,3n\right){}^{167}\text{Tm}$ reaction was measured from 17 to 22 MeV using quasimonoenergetic neutrons produced by the ${}^2\text{H}\left(d,n\right){}^3\text{He}$ reaction. This energy range was studied to resolve the discrepancy between previous $\left(n,3n\right)$ cross-section measurements. In addition, the absolute $\gamma$-ray branching ratios following the electron-capture decay of ${}^{167}\text{Tm}$ were measured. These results provide more reliable nuclear data for an important diagnostic that is used at the National Ignition Facility to estimate the yield of reaction-in-flight neutrons produced via the inertial-confinement-fusion plasma in deuterium-tritium capsules.

The rare-earth region of the nuclear table around the quasi-doubly magic nucleus ${}^{146}\text{Gd}$ is one of the very few places in which the Gamow-Teller (GT) resonance can be populated in $\beta$ decay. The appropriate technique to study such a phenomenon is total absorption spectroscopy, thanks to which one can measure the $B$(GT) distribution in $\beta$-decay experiments even when it is very fragmented and lies at high excitation energy in the daughter nucleus. Results on the GT resonance measured in the $\beta$ decay of the odd-$Z, N=83$ nuclei ${}^{148}\text{Tb}, {}^{150}\text{Ho}$, and ${}^{152}\text{Tm}$ are presented in this work and compared with shell-model calculations. The tail of the resonance is clearly observed up to the limit imposed by the $Q$ value. This observation is important in the context of the understanding of the “quenching” of the GT strength.

Low-spin states in the neutron-rich, $N=90$ nuclide ${}^{146}\mathrm{Ba}$ were populated following $\beta$ decay of ${}^{146}\mathrm{Cs}$, with the goal of clarifying the development of deformation in barium isotopes through delineation of their nonyrast structures. Fission fragments of ${}^{146}\mathrm{Cs}$ were extracted from a 1.7-Ci ${}^{252}\mathrm{Cf}$ source and mass selected using the CAlifornium Rare Ion Breeder Upgrade (CARIBU) facility. Low-energy ions were deposited at the center of a box of thin $\beta$ detectors, surrounded by a highly efficient high-purity Ge array. The new ${}^{146}\mathrm{Ba}$ decay scheme now contains 31 excited levels extending up to $\sim 2.5$ MeV excitation energy, double what was previously known. These data are compared to predictions from the interacting boson approximation (IBA) model. It appears that the abrupt shape change found at $N=90$ in Sm and Gd is much more gradual in Ba and Ce, due to an enhanced role of the $\gamma$ degree of freedom.

In this paper we study the number of states with given spin for identical particles, denoted as $D_I^n\left(l\right)$ for bosons and as ${\mathcal{D}}_I^n\left(j\right)$ for fermions, where $I$ is the total angular momentum of the system, $n$ is the particle number, $l$ is the spin of a single boson, and $j$ is the spin of a single fermion. We derive relations of $D_I^n\left(l\right)$ and ${\mathcal{D}}_I^n\left(j\right)$; in particular, we obtain recursive and explicit formulas of $D_I^n\left(l\right)$ and ${\mathcal{D}}_I^n\left(j\right)$ in terms of those for $n-1$ particles and apply them to systems of two, three, and five identical particles.

Leading three-baryon forces are derived within SU(3) chiral effective field theory. Three classes of irreducible diagrams contribute: three-baryon contact terms, one-meson exchange, and two-meson exchange diagrams. We provide the minimal nonrelativistic terms of the chiral Lagrangian that contribute to these diagrams. SU(3) relations are given for the strangeness $S=0$ and $-1$ sectors. In the strangeness-zero sector we recover the well-known three-nucleon forces from chiral effective field theory. Explicit expressions for the $\mathrm{\Lambda }NN$ chiral potential in isospin space are presented.

We investigate the extent to which theories of collective motion can capture the physics that determines the nuclear matrix elements governing neutrinoless double-$\beta$ decay. To that end we calculate the matrix elements for a series of isotopes in the full $pf$ shell, omitting no spin-orbit partners. With the inclusion of isoscalar pairing, a separable collective Hamiltonian that is derived from the shell model effective interaction reproduces the full shell-model matrix elements with good accuracy. A version of the generator coordinate method that includes the isoscalar pairing amplitude as a coordinate also reproduces the shell model results well, an encouraging result for theories of collective motion, which can include more single-particle orbitals than the shell model. We briefly examine heavier nuclei relevant for experimental double-$\beta$ decay searches, in which shell-model calculations with all spin-orbit partners are not feasible; our estimates suggest that isoscalar pairing also plays a significant role in these nuclei, though one we are less able to quantify precisely.

We analyze ${}^{16}\mathrm{O}\text{−}{}^{16}\mathrm{O}$ and ${}^{12}\mathrm{C}\text{−}{}^{12}\mathrm{C}$ scattering with the microscopic coupled-channels method and investigate the coupled-channels and three-nucleon-force (3NF) effects on elastic and inelastic cross sections. In the microscopic coupled-channels calculation, the Melbourne $g$-matrix interaction modified according to the chiral 3NF effects is used. It is found that the coupled-channels and 3NF effects additively change both the elastic and inelastic cross sections. As a result, the coupled-channels calculation including the 3NF effects significantly improves the agreement between the theoretical results and the experimental data. The incident-energy dependence of the coupled-channels and 3NF effects is also discussed.