The study of nuclear physics using lattice QCD is hindered by an exponentially large signal-to-noise problem that is conventionally alleviated by raising the quark masses to unphysically high values. We propose a novel form of partial quenching for calculations involving nucleons in which the sea quark masses are taken to be smaller than the valence quark masses. It is shown that lowering the sea quark masses toward their physical values actually improves signal-to-noise. An optimized approach to the physical point in the ($m_s$, $m_v$) plane is proposed, with a full analysis of the cost benefit. Improvements in computing time of $~$${10}^{2(A-1)}$, where $A$ is the number of nucleons in the system, are shown to be possible.

Using the finite-temperature quasiparticle random phase approximation (FTQRPA) on the basis of the finite-temperature Skyrme-Hartree-Fock$\hspace{0.5em}+\hspace{0.5em}$Bardeen-Cooper-Schrieffer (BCS) method, we study ${\beta }^{-}$-decay half-lives for even-even neutron magic nuclei with $N=82$ in a finite-temperature environment. We find that the ${\beta }^{-}$-decay half-life first decreases as the temperature increases for all the nuclei we study, although the thermal effect is found to be small at temperatures relevant to $r$-process nucleosynthesis. Our calculations indicate that the half-life begins to increase at high temperatures for open-shell nuclei. We discuss this behavior in connection to the pairing phase transition.

We show that the gravitational binding energy of a neutron star of a given mass is correlated with the slope of the nuclear symmetry energy at 1–2 times nuclear saturation density for equations of state without significant softening (i.e., those that predict maximum masses $M_{\max }>1.44M_{\odot }$ in line with the largest accurately measured neutron star mass). Applying recent laboratory constraints on the slope of the symmetry energy to this correlation we extract a constraint on the baryon mass of the lower mass member of the double pulsar binary system, PSR J0737-3039B. We compare with independent constraints derived from modeling the progenitor star of J0737-3039B up to and through its collapse under the assumption that it formed in an electron capture supernova. The two sets of constraints are consistent only if $L\lesssim$ 70 MeV.

Low-lying collectively excited states of ${}^{128}\mathrm{Xe}$ were investigated by $\gamma$-ray spectroscopy following the ${}^{12}\mathrm{C}({}^{128}\mathrm{Xe},{}^{128}\mathrm{Xe}{}^{*}){}^{12}\mathrm{C}$ projectile Coulomb excitation reaction. Nineteen absolute $E2$ transition strengths were obtained including the first measurement of the critical $B(E2)$ decays from the second and third $J^{\pi }=0^{+}$ states. These data are compared with the theoretical predictions of the critical point symmetry E(5) and allow us to conclude that ${}^{128}\mathrm{Xe}$ is not an E(5) nucleus as previously suggested, leaving ${}^{130}\mathrm{Xe}$ as the most likely candidate among the Xe isotopes.

The reaction $\gamma p\to K^{+}\Lambda$ has been investigated over the center-of-momentum energy, $W$, range from threshold up to $2.2$ GeV in a tree-level effective Lagrangian model that incorporates most of the well-established baryon resonances with spins equal to or below $\frac{5}{2}$. Four less well-established nucleon resonances of higher mass are also included. The fitted parameters consist, for each resonance included, of the products of the coupling strengths at the electromagnetic and strong interaction vertices and, for the less-established nucleon resonances, of the total decay width. For the well-established nucleon resonances, the energy and momentum dependence of the widths are treated within a dynamical model that is normalized to give the empirical decay branching ratios on the resonance mass shells. For the less-established resonances, the total decay width is treated as a single parameter independent of the reaction kinematics. The model is used to fit recent data for the unpolarized differential cross section (CLAS), the induced hyperon polarization asymmetry, $P$ (CLAS, GRAAL, SAPHIR), the beam spin asymmetry, $\Sigma$ (LEPS and GRAAL), and the double-polarization observables $C_x$ and $C_z$ (CLAS). The model results were also compared with LEPS data for the unpolarized differential cross section, but those data were not included in the fit. Two different fits were obtained: one that incorporates SU(3)-symmetry constraints on the Born contributions to the reaction amplitude and one in which these constraints are relaxed. Explicit numerical results are given only for the first fit because the two fits gave nearly identical results for the observables and the ${\chi }^2$ per degree of freedom obtained with the second fit was only marginally better than that of the first fit ($<1\%$ better). Results are presented for the fitted observables at several different energies and center-of-momentum (CM) frame kaon angles.

We present a theory of neutrino interactions with nuclei aimed at the description of the partial cross sections, namely quasielastic and multinucleon emission, coherent and incoherent single-pion production. For this purpose, we use the theory of nuclear responses treated in the random-phase approximation, which allows a unified description of these channels. It is particularly suited for the coherent pion production where collective effects are important, whereas they are moderate in the other channels. We also study the evolution of the neutrino cross sections with the mass number from carbon to calcium. We compare our approach to the available neutrino experimental data on carbon. We put a particular emphasis on the multinucleon channel, which at present is not easily distinguishable from the quasielastic events. This component turns out to be quite relevant for the interpretation of experiments (K2K, MiniBooNE, SciBooNE). It can account in particular for the unexpected behavior of the quasielastic cross section.

Proton-deuteron radiative capture and two- and three-body photodisintegration of ${}^3\mathrm{He}$ at low energy are described using realistic hadronic dynamics and including the Coulomb force. The sensitivity of the observables to the relativistic corrections of the one-nucleon electromagnetic current operator is studied. Significant effects of the relativistic spin-orbit charge are found for the vector-analyzing powers in the proton-deuteron radiative capture and for the beam-target parallel-antiparallel spin asymmetry in the three-body photodisintegration of ${}^3\mathrm{He}$.

Excited states in ${}^{142}\mathrm{Cs}$ and ${}^{144}\mathrm{Cs}$, populated in the spontaneous fission of ${}^{248}\mathrm{Cm}$ and ${}^{252}\mathrm{Cf}$ and in thermal neutron-induced fission of ${}^{235}\mathrm{U}$ and ${}^{242}\mathrm{Am}$ were studied by means of $\gamma$ spectroscopy using the EUROGAM2 and Gammasphere multidetector Ge arrays and the LOHENGRIN fission-fragment separator, respectively. In ${}^{142}\mathrm{Cs}$, a band and an isomer with a half-life of $T_{1/2}=11(3)$ ns have been identified. Spins and parities have been proposed for excited levels in this nucleus. In ${}^{144}\mathrm{Cs}$ excited levels have been observed. A $T_{1/2}=1.1(1)$ $\mu$s isomer was found with a $\gamma$ cascade, which probably feeds this isomer. There is also an indication of a nanosecond isomer in ${}^{144}\mathrm{Cs}$. Quasiparticle-rotor model calculations done in this work allowed proton-neutron configurations to be proposed for levels in ${}^{142}\mathrm{Cs}$ and ${}^{144}\mathrm{Cs}$.

The giant resonance region from $9$ MeV $<E_x<60$ MeV in ${}^{24}\mathrm{Mg}$ has been studied with inelastic scattering of $240$-MeV $\alpha$ particles at small angles, including $0^{°}$. Isoscalar $E0$, $E1$, $E2$, and $E3$ strength was identified from $9$ MeV $<E_x<40$ MeV and the effects of differing continua studied.

Based on an exact formalism, we study the effects of isospin-symmetry-breaking interactions on superallowed $0^{+}\to 0^{+}$ transitions. We calculate the second-order renormalization of the Fermi matrix element due to radial contributions and show that radial excitations neglected in the treatment of Towner and Hardy are significant. These are estimated to decrease the isospin-symmetry-breaking corrections. Our results provide a correction term that can be included in existing approaches.

Using Monte Carlo generators of the PYTHIA model for hadron-hadron collisions and a multiphase transport (AMPT) model for nucleus-nucleus collisions, the longitudinal boost invariance of charge balance function and its transverse-momentum dependence are carefully studied. It shows that the charge balance function is boost invariant in both $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions in these two models, consistent with experimental data. The balance function properly scaled by the width of the pseudorapidity window is independent of the position or the size of the window and is corresponding to the balance function of the whole pseudorapidity range. This longitudinal property of balance function also holds for particles in small transverse-momentum ranges in the PYTHIA and the AMPT default models, but is violated in the AMPT with string melting. The physical origin of the results is discussed.

The HARP Collaboration has presented measurements of the double-differential ${\pi }^{\pm }$ production cross section in the range of momentum $100\hspace{0.5em}\text{MeV}/c⩽p⩽800\hspace{0.5em}\text{MeV}/c$ and angle $0.35\hspace{0.5em}\text{rad}⩽\theta ⩽2.15\hspace{0.5em}\text{rad}$ with proton beams hitting thin nuclear targets. In many applications the extrapolation to long targets is necessary. In this article the analysis of data taken with long (one interaction length) solid cylindrical targets made of carbon, tantalum, and lead is presented. The data were taken with the large-acceptance HARP detector in the T9 beam line of the CERN proton synchrotron. The secondary pions were produced by beams of protons with momenta of 5, 8, and $12\text{GeV}/c$. The tracking and identification of the produced particles were performed using a small-radius cylindrical time projection chamber placed inside a solenoidal magnet. Incident protons were identified by an elaborate system of beam detectors. Results are obtained for the double-differential yields per target nucleon ${\mathrm{d}}^2\sigma /\mathrm{d}p\mathrm{d}\theta$. The measurements are compared with predictions of the MARS and GEANT4 Monte Carlo simulations.

The productions of thorium and uranium are key ingredients in $r$-process nucleo-cosmochronology. With the combination of improved nuclear and stellar data, we have made a detailed investigation of the $r$-process abundance pattern in the very metal-poor halo stars based on the classical $r$-process approach. It is found that the results are almost independent of specified simulations to observed abundances. The influence from nuclear mass uncertainties on a Th/U chronometer can approach 2 Gyr. Moreover, the ages of the metal-poor stars HE $1523-0901$, CS $31082-001$, and BD $+{17}^{°}3248$ are determined as $11.8\pm 3.7$, $13.5\pm 2.9$, and $10.9\pm 2.9$ Gyr, respectively. The results can serve as an independent check for age estimates of the Universe.

A scenario is suggested in which the three light quark flavors are sequentially deconfined under increasing pressure in cold asymmetric nuclear matter as found, for example, in neutron stars. The basis for this analysis is a chiral quark matter model of Nambu–Jona-Lasinio (NJL) type with diquark pairing in the spin-1 single-flavor, spin-0 two-flavor, and three-flavor channels. Nucleon dissociation sets in at about the saturation density, $n_0$, when the down-quark Fermi sea is populated ($d$-quark drip line) because of the flavor asymmetry induced by $\beta$ equilibrium and charge neutrality. At about $3n_0$, $u$-quarks appear and a two-flavor color superconducting (2SC) phase is formed. The $s$-quark Fermi sea is populated only at still higher baryon density, when the quark chemical potential is of the order of the dynamically generated strange quark mass. Two different hybrid equations of state (EOSs) are constructed using the Dirac-Brueckner Hartree-Fock (DBHF) approach and the EOS of Shen et al. [H. Shen, H. Toki, K. Oyamatsu, and K. Sumiyoshi, Nucl. Phys. A637, 435 (1998)] in the nuclear matter sector. The corresponding hybrid star sequences have maximum masses of 2.1 and 2.0 ${\mathrm{M}}_{\odot }$, respectively. Two- and three-flavor quark-matter phases exist only in gravitationally unstable hybrid star solutions in the DBHF case, whereas the Shen-based EOSs produce stable configurations with a 2SC phase component in the core of massive stars. Nucleon dissociation via $d$-quark drip could act as a deep crustal heating process, which apparently is required to explain superbursts and cooling of x-ray transients.

New experimental information has been recently obtained on the odd-odd nucleus ${}^{134}\mathrm{I}$. We interpret the five observed excited states up to the energy of $~3$ MeV on the basis of a realistic shell-model calculation and make spin-parity assignments accordingly. A very good agreement is found between the experimental and calculated energies.

The contribution of the low-lying nucleon resonances $P_{33}(1232)$, $P_{11}(1440)$, $D_{13}(1520)$, and $S_{11}(1535)$ to the invariant-mass spectra of di-electrons stemming from the exclusive processes $\mathit{pp}\to \mathit{pp}\hspace{0.5em}{e}^{+}{e}^{-}$ and $\mathit{pn}\to \mathit{pn}\hspace{0.5em}{e}^{+}{e}^{-}$ is investigated within a fully covariant and gauge-invariant diagrammatical approach. We employ, within the one-boson exchange approximation, effective nucleon-meson interactions including the exchange mesons $\pi$, $\eta$, $\sigma$, $\omega$, and $\rho$ as well as excitations and radiative decays of the above low-lying nucleon resonances. The total contribution of these resonances is dominant; however, bremsstrahlung processes in $\mathit{pp}$ and, in particular, $\mathit{pn}$ collisions at beam energies of $1–2$ GeV are still significant in certain phase-space regions.

We study the validity of pair truncation of the nuclear shell model by using the semimagic nucleus ${}^{46}\mathrm{Ca}$. We present low-lying states and their $E2$ transition rates based on both nucleon pair approximation (NPA) and exact shell-model (SM) calculations. We also calculate overlaps between wave functions of low-lying states calculated by using the NPA and those calculated by using the SM. Our calculated results show a remarkable agreement between the NPA results and the SM results, although the NPA is a drastic truncation of the SM.

The computation of radiative energy loss in a finite-size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultrarelativistic heavy-ion collisions. We here present a theoretical formalism for the calculation of the first order in opacity radiative energy loss of a quark jet traveling through a finite-size dynamical QCD medium. We show that, while each individual contribution to the energy loss is infrared divergent, the divergence is naturally regulated once all diagrams are taken into account. Finite-size effects are shown to induce a nonlinear path-length dependence of the energy loss, recovering both the incoherent Gunion-Bertsch limit, as well as destructive Landau-Pomeanchuk-Migdal limit. Finally, our results suggest a remarkably simple general mapping between energy-loss expressions for static and dynamical QCD media.

Single-particle state assignments in ${}^{251}\mathrm{Cf}$ and ${}^{249}\mathrm{Cm}$ at $~1$ MeV excitation have been deduced from cross sections previously measured for the ${}^{250}\mathrm{Cf}(d,p){}^{251}\mathrm{Cf}$ and ${}^{248}\mathrm{Cm}({}^4\mathrm{He},{}^3\mathrm{He}){}^{249}\mathrm{Cm}$ reactions. The assignments are supported by observed cross-section signatures and intraband level spacings. The observed energies of these single-particle states, after pairing effects are removed, are in good agreement with values calculated using a Woods-Saxon single-particle potential. Neutron level diagrams, showing level spacings as a function of ${\nu }_2,{\nu }_4,$ and ${\nu }_6$, are extended to include neutron orbitals above $N=164$.