Parity ($P$) and time-reversal ($T$) violating nuclear forces create $P,T$-odd moments in expansion of the nuclear electrostatic potential. We derive expression for the nuclear electric octupole field which includes the electron screening correction (similar to the screening term in the Schiff moment). Then we calculate the $Z^2{\alpha }^2$ corrections to the Schiff moment which appear due to the finite nuclear size. Such corrections are important in heavy atoms with nuclear charge $Z>50$. The Schiff and octupole moments induce atomic electric dipole moments and $P,T$-odd interactions in molecules which are measured in numerous experiments to test $CP$-violation theories.

The prompt $\gamma$-$\gamma$ coincidence technique has been used to carry out the spectroscopic study of the level schemes and to derive the relative isotopic yield distributions of fission fragment nuclei employing the ${}^{235}$U($n_{th}$, $f$) reaction for the first time. From the coincidence rates of various Ba isotopes with ${}^{90}$Kr nucleus and of Sr isotopes with ${}^{138}$Xe nucleus, it has been found that either the $2n$ or $3n$ neutron evaporation channels dominate during the fission process. The average angular momenta for three complementary pairs have been estimated. The yrast and near-yrast level structures in several isotopes of six elements (Sr, Xe, Kr, Ba, Zr, and Te) have been deduced. The level schemes obtained are compared with earlier reported works, where different reactions or spontaneous fission (SF) data were used.

Background: ${}^{139}$Pr is located in a transitional region of neutron number close to the $N=82$ shell. The study of its high-spin states and collective bands is important for systematically understanding the nuclear structural characteristics in this region.

Purpose: To investigate the high-spin levels and to search for oblate bands in ${}^{139}$Pr.

Methods: The high-spin states of ${}^{139}$Pr have been studied via the reaction ${}^{124}$Sn(${}^{19}$F,4$n$) at a beam energy of 80 MeV. The experiment was carried out at the HI-13 Tandem Accelerator at the China Institute of Atomic Energy (CIAE). The data analysis was done by using the $\gamma$-$\gamma$ coincidence method.

Results: The level scheme of ${}^{139}$Pr has been expanded with spin up to 45/2$\hslash$. A total of 39 new levels and 45 new transitions are identified. Four collective band structures at high-spin states have been newly established. From systematic analysis, one of the bands is proposed as a double decoupled band; two bands are proposed as oblate bands with $\gamma \sim -{60}^{\circ }$; another band is suggested as an oblate-triaxial band with $\gamma \sim -{90}^{\circ }$. The other characteristics for these bands are discussed.

Conclusions: A new level scheme in ${}^{139}$Pr has been established and the collective bands at high spin have been identified. The result shows that the strong oblate shape-driving effect is caused by neutrons at the high-spin states in ${}^{139}$Pr.

The phonon damping model is extended to include the effect of angular momentum at finite temperature. The model is applied to the study of damping of the giant dipole resonance (GDR) in hot and noncollectively rotating spherical nuclei. The numerical results obtained for ${}^{88}$Mo and ${}^{106}$Sn show that the GDR width increases with both temperature $T$ and angular momentum $M$. At $T>$ 4 MeV and $M⩽$ 60$\hslash$ the increase in the GDR width slows down for ${}^{106}$Sn, whereas at $M⩾$ 80$\hslash$ the GDR widths in both nuclei nearly saturate. By adopting the nuclear shear viscosity extracted from fission data at $T=$ 0, it is shown that the maximal value of the angular momentum for ${}^{88}$Mo and ${}^{106}$Sn should be around 46$\hslash$ and 55$\hslash$, respectively, so that the universal conjecture for the lower bound of the specific shear viscosity for all fluids is not violated up to $T=$ 5 MeV.

We study boron, carbon, nitrogen, and oxygen isotopes with a newly constructed shell-model Hamiltonian developed from a monopole-based universal interaction ($V_{MU}$). The present Hamiltonian can reproduce well the ground-state energies, energy levels, electric quadrupole properties, and spin properties of these nuclei in full $psd$ model space including $(0-3)\hslash \omega$ excitations. Especially, it correctly describes the drip lines of carbon and oxygen isotopes and the spins of the ground states of ${}^{10}$B and ${}^{18}$N while some former interactions such as WBP and WBT fail. We point out that the inclusion of $2\hslash \omega$ excitations is important in reproducing some of these properties. In the present $(0+2)\hslash \omega$ calculations small but constant $E2$ effective charges appear to work quite well. As the inclusion of the $2\hslash \omega$ model space makes a rather minor change, this seems to be related to the smallness of the ${}^4$He core. Similarly, the spin $g$ factors are very close to free values. The applicability of tensor and spin-orbit forces in free space, which are taken in the present Hamiltonian, is examined in shell-model calculations.

Cross sections for ($p$,$t$) and ($t$,$p$) reactions near neutron-shell closures depend sensitively on the amount of intruder configuration in the relevant states. For several nuclei in the “island of inversion,” I present calculated cross section ratios for the first two 0${}^{+}$ states as functions of the intruder-normal-state mixing.

Five scaling relations familiar from analyses of inclusive electron scattering spectra on complex nuclei are applied to 65 inclusive continuum spectra of protons, positive kaons, and pions incident upon carbon. Beam energies range from 300 MeV to 18.3 GeV with momentum transfers such that the conditions for quasifree scattering are met, similar to those for many electron scattering analyses. Several very strong assumptions need to be made to apply these scaling analyses to hadrons, and so the requirement that these spectra come into agreement under a scaling analysis is a severe test of these assumptions. Scaling is found in the sense that the responses of four of the five systems considered do agree over a significant range of momentum transfers for the three hadron species over a wide range of beam energies. Responses other than those for quasifree scattering destroy the validity of scaling systems for hadrons at large angles or momentum transfers or high beam energies.

Experimental photoabsorption cross sections for the nuclei ${}^{92,94,96,98,100}$Mo, ${}^{88}$Sr, ${}^{90}$Zr, and ${}^{139}$La are used as an input for calculations of $(\gamma ,n)$, $(\gamma ,p),$ and $(\gamma ,\alpha )$, as well as $(n,\gamma )$, $(p,\gamma ),$ and $(\alpha ,\gamma )$ cross sections and reaction rates at energies and temperatures relevant for nucleosynthesis network models and transmutation projects. The calculations are performed with the statistical-model code talys. The results are compared with those obtained by using different analytic standard parametrizations of $\gamma$-ray strength functions implemented in talys and with an energy-damped double-Lorentzian model. The radiative capture reaction cross sections are enhanced by the pygmy resonances in ${}^{88}$Sr, ${}^{90}$Zr, and ${}^{139}$La.

Measuring nucleon-nucleon short range correlations (SRCs) has been a goal of the nuclear physics community for many years. They are an important part of the nuclear wave function, accounting for almost all of the high-momentum strength. They are closely related to the EMC effect. While their overall probability has been measured, measuring their momentum distributions is more difficult. In order to determine the best configuration for studying SRC momentum distributions, we measured the ${}^3$He$(e,e^{\prime }pp)n$ reaction, looking at events with high-momentum protons ($p_p>0.35$ GeV/c) and a low-momentum neutron ($p_n<0.2$ GeV/c). We examined two angular configurations: either both protons emitted forward or one proton emitted forward and one backward (with respect to the momentum transfer, $\vec{q}$). The measured relative momentum distribution of the events with one forward and one backward proton was much closer to the calculated initial-state $pp$ relative momentum distribution, indicating that this is the preferred configuration for measuring SRC.

The symmetry energy, the neutron pressure, and the asymmetric compressibility of deformed neutron-rich even-even nuclei are calculated for the examples of Kr and Sm isotopes within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related to the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the self-consistent Skyrme-Hartree-Fock plus BCS method. Results for an extended chain of Pb isotopes are also presented. A remarkable difference is found in the trend followed by the different isotopic chains: the studied correlations reveal a smoother behavior in the Pb case than in the other cases. We also notice that the neutron skin thickness obtained for ${}^{208}$Pb with the SLy4 force is found to be in a good agreement with recent data.

Background: An asymptotic normalization coefficient (ANC) characterizes the asymptotic form of a one-nucleon overlap integral required for description of nucleon-removal reactions.

Purpose: We investigate the impact of the particle continuum on proton and neutron ANCs for mirror systems from $p$- and $sd$-shell regions.

Method: We use the real-energy and complex-energy continuum-shell-model approaches.

Results: We studied the general structure of the single-particle ANCs as a function of the binding energy and orbital angular momentum. We computed ANCs in mirror nuclei for different physical situations, including capture reactions to weakly bound and unbound states.

Conclusions: We demonstrated that the single-particle ANCs exhibit generic behavior that is different for charged and neutral particles. We verified the previously proposed relation [7] between proton and neutron mirror ANCs. We find minor modifications if the spectroscopic strength is either localized in a single state or broadly distributed. For cases when several states couple strongly to the decay channel, these modifications may reach 30$\%$.

Background: Neutron-induced backgrounds are a significant concern for experiments that require extremely low levels of radioactive backgrounds such as direct dark matter searches and neutrinoless double-$\beta$ decay experiments. Unmeasured neutron scattering cross sections are often accounted for incorrectly in Monte Carlo simulations.

Purpose: The purpose of this article is to determine partial $\gamma$-ray production cross sections for ($n,xn\gamma$) reactions in natural argon for incident neutron energies between 1 and 30 MeV.

Methods: The broad-spectrum neutron beam at the Los Alamos Neutron Science Center (LANSCE) was used used for the measurement. Neutron energies were determined using time of flight, and resulting $\gamma$ rays from neutron-induced reactions were detected using the GErmanium Array for Neutron Induced Excitations (GEANIE).

Results: Partial $\gamma$-ray cross sections were measured for six excited states in ${}^{40}$Ar and two excited states in ${}^{39}$Ar. Measured ($n,xn\gamma$) cross sections were compared to the talys and CoH${}_3$ nuclear reaction codes.

Conclusions: These new measurements will help to identify potential backgrounds in neutrinoless double-$\beta$ decay and dark matter experiments that use argon as a detection medium or shielding. The measurements will also aid in the identification of neutron interactions in these experiments through the detection of $\gamma$ rays produced by ($n,xn\gamma$) reactions.

The reaction $K^{-}d\to \pi \Sigma n$ is investigated taking into account single scattering and the two-step process owing to $\overline{K}N\to \pi \Sigma$ rescattering. The influence of some common approximations are examined. It is found that the treatment of the kinematics in the Green's function that appears in the loop integral of the rescattering process has a rather strong impact on the resulting lineshape of the $\pi \Sigma$ invariant mass spectrum. Specifically, a calculation with correct kinematics where the three-body unitarity cut owing to the $n{K}^{-}p$ threshold occurs at the physical value yields a pronounced peak in the invariant mass spectrum at this threshold and, at the same time, suppresses the signal in the region of the $\Lambda$(1405) resonance. On the other hand, an approximation applied in past calculations shifts that threshold down and, consequently, leads to an accidental and therefore erroneous enhancement of the signal of the $\Lambda$(1405) in the $\pi \Sigma$ invariant mass spectrum.

Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have commonly been viewed as constant empirical mass scales that fill all space-time, are instead wholly contained within hadrons; i.e., they are a property of hadrons themselves and expressed, e.g., in their Bethe-Salpeter or light-front wave functions. We explain that this paradigm is consistent with empirical evidence and incidentally expose misconceptions in a recent Comment.

It has recently been proposed that ${}_{41}^{92}$Nb and ${}_{43}^{98}$Tc may have been formed in the $\nu$-process. We investigate the neutrino induced reactions related to the $\nu$-process origin of these two odd-odd nuclei. We find that the main neutrino reactions to produce ${}_{41}^{92}$Nb are the charged-current (CC) ${}^{92}$Zr(${\nu }_e,e^{-}$)${}^{92}$Nb and the neutral-current (NC) ${}^{93}$Nb[$\nu \left(\overline{\nu }\right),{\nu }^{\prime }{\left(\overline{\nu }\right)}^{\prime }$ $n$]${}^{92}$Nb reactions. Similarly, the main reactions for ${}_{43}^{98}$Tc, are the CC reaction ${}^{98}$Mo(${\nu }_e,e^{-}$)${}^{98}$Tc and the NC reaction ${}^{99}$Ru[$\nu \left(\overline{\nu }\right),{\nu }^{\prime }{\left(\overline{\nu }\right)}^{\prime }$$p$]${}^{98}$Tc. Our calculations are carried out using the quasiparticle random phase approximation. Numerical results are presented for the energy and temperature dependent cross sections. Since charge exchange reactions by neutrons may also lead to the formation of ${}_{41}^{92}$Nb and ${}_{43}^{98}$Tc, we also discuss the feasibility of the ${}^{92}$Mo($n,p$)${}^{92}$Nb and ${}^{98}$Ru($n,p$)${}^{98}$Tc reactions to produce these nuclei.

We discuss the role of running coupling on the thermal photon yield from quark gluon plasma. It is shown that the photon production rate from the partonic phase is considerably enhanced when running coupling is considered with respect to a fixed value. However, we show by explicit evaluation that although this difference survives the space-time evolution the experimental data cannot distinguish between the two once the hard contribution, which is an essential component of the photon production mechanism, is added.

The high spin states in ${}^{195}$Bi were studied by $\gamma$-ray spectroscopic method using the ${}^{181}$Ta(${}^{20}$Ne, 6$n$) fusion-evaporation reaction at 130 MeV. The $\gamma \gamma$ coincidence data were taken using an array of eight clover high-purity germanium detectors. The spin and parity assignments of the excited states were made from the measured directional correlation from oriented states ratios and integrated polarization asymmetry ratios. The results show, for the first time, the evidence of a rotational-like band based on a 13/2${}^{+}$ bandhead in this nucleus, indicating the onset of deformation at the neutron number $N=112$ for the bismuth isotopes. The results obtained were found to be consistent with the prediction of the total Routhian surface calculations using the Woods-Saxon potential. The same calculations also predicted a change in shape from oblate to triaxial in ${}^{195}$Bi at high rotational frequency.

The charged-current quasi-elastic scattering of muon neutrinos on calcium and argon targets is calculated for neutrino energy up to 2.8 GeV. The calculations are done within the framework of the relativistic distorted-wave impulse approximation, which was earlier successfully applied to describe electron-nucleus data. The model is first tested against experimental data for electron scattering off calcium and then it is applied to calculate (anti)neutrino cross sections on ${}^{40}$Ca and ${}^{40}$Ar. We show that reduced exclusive cross sections for neutrino and electron scattering are similar. A significant nuclear model dependence of both inclusive and total cross sections for energy about 1 GeV was found. From the comparison of the (anti)neutrino differential and total cross sections per (proton)neutron, calculated for the carbon, oxygen, and argon targets it is evident that the cross sections decrease slowly with the mass number of the target due to nuclear effects.

The complete spectrum of collective modes of the triplet order parameter in the superfluid neutron matter is examined in the BCS approximation below the pair-breaking threshold. The dispersion equations both for the unitary and nonunitary excitations are derived and solved in the limit of $q\to 0$ by taking into account the anisotropy of the energy gap for the case of $P$-wave pairing. By our analysis, there is only one Goldstone mode which is associated with the broken gauge symmetry. We found no additional Goldstone modes associated with the broken rotational symmetry but found that the oscillations of the total angular momentum are qualitatively similar to the “normal-flapping” mode in the A phase of superfluid helium. There are also two collective modes associated with internal vibrations of the structure of the order parameter oscillating with $\omega (T=0)=1.20{\Delta }_0$ and $\omega (T=0)=0.61{\Delta }_0$.