A sample of two-proton and no-pion events selected in the ArgoNeuT neutrino scattering experiment on a liquid argon target [Phys. Rev. D 90, 012008 (2014)] is analyzed with the nuwro Monte Carlo event generator. An attempt is made to estimate how likely it is to obtain observed numbers of laboratory frame and reconstructed back-to-back nucleon pairs. For laboratory frame back-to-back events, a clear data/Monte Carlo discrepancy is seen. For the reconstructed nucleon pairs, a good agreement is reported. We provide a simple kinematical argument that explains why this accordance is expected.

The highly selective, intermediate-energy heavy-ion-induced neutron-pickup reaction, in combination with $\gamma$-ray spectroscopy using the $\gamma$-ray energy-tracking in-beam nuclear array (GRETINA), is shown to provide reliable relative spectroscopic strengths for high-$\ell$ orbitals in nuclei more neutron rich than the projectile. The reaction mechanism gives a significant final-state-spin alignment that is validated through $\gamma$-ray angular-distribution measurements enabled by the position sensitivity of GRETINA. This is the first time that $\gamma$-ray angular distributions could be extracted from a high-luminosity, fast-beam reaction other than inelastic scattering. This holds great promise for the restriction and assignment of $J^{\pi }$ quantum numbers in exotic nuclei. We advance this approach to study the crucial $N=28$ shell closure and extract the ratio $g_{9/2}:f_{5/2}$ of bound neutron single-particle strengths in ${}^{49}\mathrm{Ca}$, a benchmark for emerging multi-shell ab initio and configuration-interaction theories that are applicable along the Ca isotopic chain.

Inspired by the preliminary experimental data by the CLAS Collaboration, the $K^{*0}\mathrm{\Lambda }$ photoproduction off a neutron is studied within an effective Lagrangian approach. The contributions from the Born terms including $s, u$, and $t$ channels are considered to calculate the amplitude, with which the cross sections are calculated and compared with preliminary CLAS data. The theoretical results indicate that the contribution from the $t$-channel $K$ exchange plays a dominant role for the $K^{*0}\mathrm{\Lambda }$ photoproduction. The contribution from the $\kappa$ exchange is found one order of magnitude smaller than that from the $K$ exchange. Both the Regge model and the Feynman model are applied to treat the $t$-channel contribution. The discrepancy between two models is found small in the energy range of CLAS data and predicted to become obvious at energies higher than 3 GeV. More precise experimental data especially at backward angles will be helpful to further understand the interaction mechanism of the $K^{*0}\mathrm{\Lambda }$ photoproduction.

The low-lying collective states in ${}^{128}\mathrm{Ba}$ are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. Calculated level structures and electromagnetic properties are compared with the experimental data. Theoretical structures of the collective wave functions are illustrated in detail for $0_1^{+},0_2^{+},0_3^{+},2_1^{+},2_2^{+}$, and $2_3^{+}$ states. In the present results, the main contribution to the $0_2^{+}$ state of ${}^{128}\mathrm{Ba}$ comes from the three-phonon component, and the two-phonon component is rather dominant in the $0_3^{+}$ state. The description of the wave functions is compared to the results of the general collective model.

Background: Nuclear excitation by electronic transition (NEET) is a rare nuclear excitation that can occur in isotopes containing a low-lying nuclear excited state. Over the past 40 yr, several experiments have attempted to measure NEET of ${}^{235}\mathrm{U}$ and those experiments have yielded conflicting results.

Purpose: An experiment was performed to determine whether NEET of ${}^{235}\mathrm{U}$ occurs and to determine its excitation rate.

Method: A pulsed Nd:YAG laser operating at 1064 nm with a pulse energy of 790 mJ and a pulse width of 9 ns was used to generate a uranium plasma. The plasma was collected on a catcher plate and electrons from the catcher plate were accelerated and focused onto a microchannel plate detector. An observation of a decay with a 26-min half-life would suggest the creation of ${}^{235\text{m}}\mathrm{U}$ and the possibility that NEET of ${}^{235}\mathrm{U}$ occurred.

Results: A 26-min decay consistent with the decay of ${}^{235\text{m}}\mathrm{U}$ was not observed and there was no evidence that NEET occurred. An upper limit for the NEET rate of ${}^{235}\mathrm{U}$ was determined to be ${\lambda }_{\text{NEET}}<1.8\times {10}^{-4} {\mathrm{s}}^{-1}$, with a confidence level of 68.3%.

Conclusions: The upper limit determined from this experiment is consistent with most of the past measurements. Discrepancies between this experiment and past measurements can be explained by assuming that past experiments misinterpreted the data.

Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying $E1$ excitations is the coupling of quadrupole and octupole phonons.

Purpose: In this work, the $\gamma$-decay behavior of candidates for the ${(2_1^{+}\otimes 3_1^{-})}_{1^{-}}$ state in the doubly magic nucleus ${}^{40}\mathrm{Ca}$ and in the heavier and semimagic nucleus ${}^{140}\mathrm{Ce}$ is investigated.

Methods: $(\vec{\gamma },{\gamma }^{\prime })$ experiments have been carried out at the High Intensity $\gamma$-ray Source $\left(\mathrm{HI}\gamma \mathrm{S}\right)$ facility in combination with the high-efficiency $\gamma$-ray spectroscopy setup ${\gamma }^3$ consisting of HPGe and ${\mathrm{LaBr}}_3$ detectors. The setup enables the acquisition of $\gamma \text{−}\gamma$ coincidence data and, hence, the detection of direct decay paths.

Results: In addition to the known ground-state decays, for ${}^{40}\mathrm{Ca}$ the decay into the $3_1^{-}$ state was observed, while for ${}^{140}\mathrm{Ce}$ the direct decays into the $2_1^{+}$ and the $0_2^{+}$ state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for $N=82$ isotones. In addition, negative parities for two $J=1$ states in ${}^{44}\mathrm{Ca}$ were deduced simultaneously.

Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the $1_1^{-}$ excitation in the light-to-medium-mass nucleus ${}^{40}\mathrm{Ca}$ as well as in the stable even-even $N=82$ nuclei.

The theory of $K$-shell ionization during $\alpha$ decay of the ${}_{84}\mathrm{Po}$ isotopes is considered in detail as a part of our general study of the inner shell ionization probability of heavy and superheavy nuclei. Calculations of $K$-shell ionization with allowance made for the $\alpha$-particle tunneling through the atomic Coulomb barrier have been performed in the framework of the fully quantum mechanical treatment developed for the first time by Anholt and Amundsen. Further information is available [Anholt and Amundsen, Phys. Rev. A 25, 169 (1982)]. As distinct from all previous the $K$-shell ionization calculations where the Dirac hydrogenlike wave functions have been used, we have found the discrete and continuum electron wave functions in the framework of the relativistic self-consistent Dirac-Fock method. In addition, we have taken into consideration accurately terms associated with the $\alpha$-particle tunneling. Our exact calculations show that the tunneling contribution to the ionization probability is of great importance while Anholt and Amundsen have asserted that the contribution is small. We have obtained that the $K$-shell ionization probability during $\alpha$ decay of five isotopes of ${}_{84}\mathrm{Po}$ correlate better with the available experimental data providing the tunneling is included in calculations. New calculations for $K$-shell ionization during $\alpha$ decay of superheavy elements ${}_{100}{}^{249}\mathrm{Fm},{}_{102}{}^{253}\mathrm{No},{}_{111}{}^{272}\mathrm{Rg}$, as well as ${}_{86}{}^{222}\mathrm{Rn}$ are also presented. The data may be of importance in the combined $\alpha ,\gamma ,$ and conversion-electron spectroscopy used in the superheavy element synthesis analysis.

We study the structure of the number-projected BCS (PBCS) wave function in the particle-hole basis, displaying its similarities with coupled clusters theory (CCT). The analysis of PBCS together with several modifications suggested by the CCT wave function is carried out for the exactly solvable Richardson model involving a pure pairing Hamiltonian acting in a space of equally spaced, doubly degenerate levels. We point out the limitations of PBCS to describe the nonsuperconducting regime and suggest possible avenues for improvement.

Fusion data for ${}^{40}\mathrm{Ca}+{}^{96}\mathrm{Zr}$ are analyzed by coupled-channels calculations that are based on a standard Woods-Saxon potential and include couplings to multiphonon excitations and transfer channels. The couplings to multiphonon excitations are the same as those used in a previous work. The transfer couplings are calibrated to reproduce the measured neutron transfer data. This type of calculation gives a poor fit to the fusion data. However, by multiplying the transfer couplings with a $\sqrt{2}$ one obtains an excellent fit. The scaling of the transfer strengths is supposed to simulate the combined effect of neutron and proton transfer, and the calculated one- and two-nucleon transfer cross sections are indeed in reasonable agreement with the measured cross sections.

We study charm production in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV in the parton-hadron-string-dynamics (PHSD) transport approach and the charm dynamics in the partonic and hadronic medium. The charm quarks are produced through initial binary nucleon-nucleon collisions by using the pythia event generator, taking into account the (anti-)shadowing incorporated in the eps09 package. The produced charm quarks interact with off-shell massive partons in the quark-gluon plasma and are hadronized into $D$ mesons through coalescence or fragmentation close to the critical energy density, and then interact with hadrons in the final hadronic stage with scattering cross sections calculated in an effective Lagrangian approach with heavy-quark spin symmetry. The PHSD results show a reasonable $R_{\mathrm{AA}}$ and elliptic flow of $D$ mesons in comparison to the experimental data for $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV from the ALICE Collaboration. We also study the effect of temperature-dependent off-shell charm quarks in relativistic heavy-ion collisions. We find that the scattering cross sections are only moderately affected by off-shell charm degrees of freedom. However, the position of the peak of $R_{\mathrm{AA}}$ for $D$ mesons depends on the strength of the scalar partonic forces which also have an impact on the $D$ meson elliptic flow. The comparison with experimental data on the $R_{\mathrm{AA}}$ suggests that the repulsive force is weaker for off-shell charm quarks as compared to that for light quarks. Furthermore, the effects from radiative charm energy loss appear to be low compared to the collisional energy loss up to transverse momenta of $\sim 15$ GeV/$c$.

The effects of kinematic cuts on electric charge fluctuations in a gas of charged particles are discussed. We consider a very transparent example of an ideal pion gas with quantum statistics, which can be viewed as a multicomponent gas of Boltzmann particles with different charges, masses, and degeneracies. Cumulants of net electric charge fluctuations ${\chi }_n^Q$ are calculated in a static and expanding medium with flow parameters adjusted to the experimental data. We show that the transverse momentum cut, $p_{t_{\text{min}}}\le p_t\le p_{t_{\text{max}}}$, weakens the effects of Bose statistics, i.e., contributions of effectively multicharged states to higher order moments. Consequently, cuts in $p_t$ modify the experimentally measured cumulants and their ratios. We discuss the influence of kinematic cuts on the ratio of mean and variance of electric charge fluctuations in a hadron resonance gas, in the light of recent data from the STAR and PHENIX Collaborations. We find that the different momentum cuts of $p_{t_{\text{min}}}=0.2$ GeV (STAR) and $p_{t_{\text{min}}}=0.3$ GeV (PHENIX) are responsible for more than 30% of the difference between these two data sets. We argue that the $p_t$ cuts imposed on charged particles will influence the normalized kurtosis ${\kappa }_Q{\sigma }_Q^2={\chi }_4^Q/{\chi }_2^Q$ of the electric charge fluctuations. In particular, the reduction of ${\kappa }_Q{\sigma }_Q^2$ with increasing $p_{t_{\text{min}}}$ will lead to differences between PHENIX and STAR data of $\mathcal{O}(6\%)$, which currently are buried under large statistical and systematic errors. We furthermore introduce the relation between momentum cutoff and finite volume effects, which is of relevance for the comparison between experimental data and lattice QCD calculations.

To explore a possible indirect method for ${}^8\mathrm{Be}$ induced astrophysical reactions, the ${}^9\mathrm{Be}=({}^8\mathrm{Be}+\mathit{n})$ cluster structure has been studied via the Trojan horse method. For the first time a ${}^8\mathrm{Be}$ nucleus having an ultrashort lifetime is studied by the Trojan horse method and a ${}^9\mathrm{Be}$ nucleus in the ground state is used for this purpose. The ${}^9\mathrm{Be}$ nucleus is assumed to have a (${}^8\mathrm{Be}+\mathit{n}$) cluster structure and used as a Trojan horse nucleus. The ${}^8\mathrm{Be}$ nucleus acts as a participant, while the neutron is a spectator to the virtual ${}^8\mathrm{Be}+\mathit{d}\to \alpha +{}^6\mathrm{Li}$ reaction via the 3-body reaction ${}^9\mathrm{Be}+\mathit{d}\to \alpha +{}^6\mathrm{Li}+\mathit{n}$. The experimental neutron momentum distribution inside ${}^9\mathrm{Be}$ has been reconstructed. The agreement between the experimental momentum distribution and the theoretical one indicates that a (${}^8\mathrm{Be}+\mathit{n}$) cluster structure inside ${}^9\mathrm{Be}$ is very likely. Therefore, the experimental study of ${}^8\mathrm{Be}$ induced reactions, for example, the measurement of the ${}^8\mathrm{Be}+\alpha \to {}^{12}\mathrm{C}$ reaction proceeding through the Hoyle state, is possible.

In this work, I take into consideration the Pauli exclusion principle (PEP) in the quasiparticle random-phase approximation (QRPA) calculations for the deformed systems by replacing the traditional quasiboson approximation (QBA) with the renormalized one. With this new formalism, the parametrization of QRPA calculations has been changed and the collapse of QRPA solutions could be avoid for realistic $g_{pp}$ values. I further find that the necessity of the renormalization parameter of particle-particle residual interaction $g_{pp}$ in QRPA calculations is due to the exclusion of PEP. So with the inclusion of PEP, I could easily extend the deformed QRPA calculations to the less-explored region where lack of experimental data prevent effective parametrization of $g_{pp}$ for QRPA methods. With this theoretical improvement, I give predictions of weak decay rates for even-even isotopes in the rare-earth region and compare the results with existing calculations.

Excited states in the neutron-deficient odd-odd proton-unbound nuclide ${}^{158}\mathrm{Ta}$ have been investigated in two separate experiments. In the first experiment, ${}^{166}\mathrm{Ir}$ nuclei were produced in the reactions of 380 MeV ${}^{78}\mathrm{Kr}$ ions with an isotopically enriched ${}^{92}\mathrm{Mo}$ target. The $\alpha$-decay chain of the $9^{+}$ state in ${}^{166}\mathrm{Ir}$ was analyzed. Fine structure in the $\alpha$ decay of the $9^{+}$ state in ${}^{162}\mathrm{Re}$ established a 66 keV difference in excitation energy between the lowest-lying $9^{+}$ and ${10}^{+}$ states in ${}^{158}\mathrm{Ta}$. Higher-lying states in ${}^{158}\mathrm{Ta}$ were populated in the reactions of 255 MeV ${}^{58}\mathrm{Ni}$ ions with an isotopically enriched ${}^{102}\mathrm{Pd}$ target. Gamma-ray decay paths that populate, depopulate, and bypass a ${19}^{-}$ isomeric state have been identified. The general features of the deduced level scheme are discussed and the prospects for observing proton emission branches from excited states are considered.

Forbidden nonunique $\beta$ decays feature shape functions that are complicated combinations of different nuclear matrix elements and phase-space factors. Furthermore, they depend in a very nontrivial way on the values of the weak coupling constants, $g_{\mathrm{V}}$ for the vector part and $g_{\mathrm{A}}$ for the axial-vector part. In this work we include also the usually omitted second-order terms in the shape functions to see their effect on the computed decay half-lives and electron spectra ($\beta$ spectra). As examples we study the fourth-forbidden nonunique ground-state-to-ground-state ${\beta }^{-}$ decay branches of ${}^{113}\mathrm{Cd}$ and ${}^{115}\mathrm{In}$ using the microscopic quasiparticle-phonon model and the nuclear shell model. A striking new feature that is reported in this paper is that the calculated shape of the $\beta$ spectrum is quite sensitive to the values of $g_{\mathrm{V}}$ and $g_{\mathrm{A}}$ and hence comparison of the calculated with the measured spectrum shape opens a way to determine the values of these coupling constants. This article is designed to show the power of this comparison, coined spectrum-shape method (SSM), by studying the two exemplary $\beta$ transitions within two different nuclear-structure frameworks. While the SSM seems to confine the $g_{\mathrm{V}}$ values close to the canonical value $g_{\mathrm{V}}=1.0$, the values of $g_{\mathrm{A}}$ extracted from the half-life data and by the SSM emerge contradictory in the present calculations. This calls for improved nuclear-structure calculations and more measured data to systematically employ SSM for determination of the effective value of $g_{\mathrm{A}}$ in the future.

Lifetimes of excited states in the neutron-deficient odd-odd nucleus ${}^{166}\mathrm{Re}$ have been measured for the first time using the recoil distance Doppler-shift method. The measured lifetime for the $\left(8^{-}\right)$ state; $\tau =480$ (80) ps, enabled an assessment of the multipolarities of the $\gamma$ rays depopulating this state. Information on electromagnetic transition strengths were deduced for the $\gamma$-ray transitions from the $\left(9^{-}\right),\left({10}^{-}\right)$, and $\left({11}^{-}\right)$ states, and in the case of the $\left({10}^{-}\right)$ and $\left({11}^{-}\right)$ states limits on the $B\left(M1\right)$ and $B\left(E2\right)$ strengths were estimated. The results are compared with total Routhian surface predictions and semiclassical calculations. Tilted-axis cranking calculations based on a relativistic mean-field approach (TAC-RMF) have also been performed in order to test the possibility of magnetic rotation in the ${}^{166}\mathrm{Re}$ nucleus. While the TAC-RMF calculations predict a quadrupole-deformed nuclear shape with similar ${\beta }_2$ deformation as obtained by using the TRS model, it was found that the experimental electromagnetic transition rates are in better agreement with a collective-rotational description.

A method is suggested to decompose the statistical and systematic uncertainties from the residues between the calculation of a theoretical model and the observed data. The residues and the parameters of the model can be obtained through the standard statistical fitting procedures. The present work concentrates on the decomposition of the total uncertainty, of which the distribution corresponds to that of the residues. The distribution of the total uncertainty is considered as two normal distributions, statistical and systematic uncertainties. The standard deviation of the statistical part, ${\sigma }_{\mathrm{stat}}$, is estimated through random parameters distributed around their best fitted values. The two normal distributions are obtained by minimizing the moments of the distribution of the residues with the fixed ${\sigma }_{\mathrm{stat}}$. The method is applied to the liquid drop model (LD). The statistical and systematic uncertainties are decomposed from the residues of the nuclear binding energies with and without the consideration of the shell effect in LD. The estimated distributions of the statistical and systematic uncertainties can well describe that of the residues. The normal assumption of the distribution of the statistical and systematic uncertainties is examined through various approaches. The comparison between the distributions of the specific nuclei and those of the statistical and systematic uncertainties are consistent with the physical considerations, although the latter two can be obtained without the knowledge of these considerations. Such as, the LD are more suitable to describe the heavy nuclei. The light and heavy nuclei are indeed distributed mostly inside the distributions of the systematic and statistical uncertainties, respectively. A similar situation is also found for the nuclei close to and far from shell. The present method is also performed for nuclei around the stability line. The results are used to investigate all measured nuclei, which show the usefulness of the uncertainty decomposition method in the exploration of the unmeasured nuclei.

Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor $T^{\mu \nu }$ and four-currents $j^{\mu }$ do not deviate considerably from the equilibrium ideal-fluid form, but the ones constructed from transport do not necessarily possess this property. In this work we investigate the space-time picture of $T^{\mu \nu }$ deviations from equilibrium in Au+Au collisions using a coarse-grained transport approach. The collision energy is varied in the range $E_{\mathrm{lab}}=5–160A\text{GeV}$. The sensitivity of $T^{\mu \nu }$ deviations from equilibrium to collision centrality, and other parameters such as the switching criterion, the amount of statistics used to construct the initial state, and the smearing parameter $\sigma$ are investigated. For low statistics, deviations of $T^{\mu \nu }$ from equilibrium are large and dominated by the effect of finite sampling. For large statistics, the pressure anisotropy plays the most significant role, while the off-diagonal components of $T^{\mu \nu }$ are small in a large volume during the whole evolution. For all considered energies and centralities the pressure anisotropy exhibits a similar feature: there is a narrow interval of time when it rapidly drops in a considerable volume. This allows us to introduce an “isotropization time,” which is found to decrease with energy and slightly increase with centrality. The isotropization times are larger than times typically used for initializing hydrodynamics.

We have recently highlighted the presence of a periodically oscillating 10% modulation in the BABAR Collaboration data on the proton timelike form factors, expressing the deviations from the pointlike behavior of the proton-antiproton electromagnetic current in the reaction $e^{+}+e^{-}\to \overline{p}+p$. Here we deepen our previous data analysis and confirm that in the case of several standard parametrizations it is possible to write the form factor in the form $F_0+F_{\mathrm{osc}}$, where $F_0$ is a parametrization expressing the long-range trend of the form factor (for $q^2$ ranging from the $\overline{p}p$ threshold to 36 ${\mathrm{GeV}}^2$), and $F_{\mathrm{osc}}$ is a function of the form $exp(-Bp)cos\left(Cp\right)$, where $p$ is the relative momentum of the final $\overline{p}p$ pair. Error bars allow for a clean identification of the main features of this modulation for $q^2<10{\mathrm{GeV}}^2$. Assuming this oscillatory modulation to be an effect of final-state interactions between the forming proton and the antiproton, we propose a phenomenological model based on a double-layer imaginary optical potential. This potential is flux absorbing when the distance between the proton and antiproton centers of mass is $\gtrsim 1.7–1.8$ fm and flux generating when it is $\lesssim 1.7–1.8$ fm. The main features of the oscillations may be reproduced with some freedom in the potential parameters, but the transition between the two layers must be sudden (0–0.2 fm) to get the correct oscillation period. The flux-absorbing part of the $\overline{p}p$ interaction is well known in the phenomenology of small-energy antiproton interactions and is due to the annihilation of $\overline{p}p$ pairs into multimeson states. We interpret the flux-creating part of the potential as due to the creation of a $1/q$-ranged state when the virtual photon decays into a set of current quarks and antiquarks. This short-lived compact state may be expressed as a sum of several hadronic states including the ones with large mass $Q_n\gg q$, that may exist for a time $t\sim 1/(Q_n-q)$. The decay of these large-mass states leads to an intermediate-stage regeneration of the $\overline{p}p$ channel.