The nuclear excitation by electron capture (NEET) process may occur when the energy differences between two nuclear levels and between two electronic states are nearly equal, provided the quantum selection rules are fulfilled. These resonant conditions drastically limit the number of possible candidates, even though thermodynamic conditions encountered in hot dense plasmas do modify the orbital electronic binding energy and the resonance conditions. ${}^{201}\mathrm{Hg}$, with a low-lying isomeric state located at $1.565$ keV, can be excited by NEET process in a laser-created plasma. However, its correct calculation requires nonlocal thermodynamic equilibrium (non-LTE) atomic physics treatment because current laser-created plasmas do not reach high-enough temperature in the area at LTE. In this article, we describe the calculation leading to an estimated excitation rate and discuss the influence of LTE$/$non-LTE physics with an average-atom model and the use of a Gaussian variance calculation to estimate the broadening around the mean energy mismatch.

The construction of differential cross sections as a function of excitation energy for systems with a collection of low- and high-lying intrinsic vibrational modes has been attempted in the past. A prescription is proposed here that simplifies the implementation of such calculation schemes with a remarkable reduction in computational time.

We construct the most general, relativistically invariant, contact Lagrangian at order $Q^2$ in the power counting, with $Q$ denoting the low momentum scale. A complete, but nonminimal, set of (contact) interaction terms is identified, which upon nonrelativistic reduction generate two leading independent operator combinations of order $Q^0$ and seven subleading ones of order $Q^2$—a result derived previously in the heavy-baryon formulation of effective field theories (EFTs). We show that Poincaré covariance of the theory requires that additional terms with fixed coefficients be included, to describe the two-nucleon potential in reference frames other than the center-of-mass frame. These terms will contribute in systems with mass number $A>2$, and their impact on EFT calculations of binding energies and scattering observables in these systems should be studied.

We have investigated the isoscalar giant resonances in the Sn isotopes using inelastic scattering of $386$-MeV $\alpha$ particles at extremely forward angles, including $0^{°}$. We have obtained completely “background-free” inelastic-scattering spectra for the Sn isotopes over the angular range $0^{°}$–$9^{°}$ and up to an excitation energy of $31.5$ MeV. The strength distributions for various multipoles were extracted by a multipole decomposition analysis based on the expected angular distributions of the respective multipoles. We find that the centroid energies of the isoscalar giant monopole resonance (ISGMR) in the Sn isotopes are significantly lower than the theoretical predictions. In addition, based on the ISGMR results, a value of $K_{\tau }=-550\pm 100$ MeV is obtained for the asymmetry term in the nuclear incompressibility. Constraints on interactions employed in nuclear structure calculations are discussed on the basis of the experimentally obtained values for $K_{\infty }$ and $K_{\tau }$.

The yrast sequence of the neutron-rich dysprosium isotope ${}^{168}\mathrm{Dy}$ has been studied using multinucleon transfer reactions following collisions between a 460-MeV ${}^{82}\mathrm{Se}$ beam and an ${}^{170}\mathrm{Er}$ target. The reaction products were identified using the PRISMA magnetic spectrometer and the $\gamma$ rays detected using the CLARA HPGe-detector array. The $2^{+}$ and $4^{+}$ members of the previously measured ground-state rotational band of ${}^{168}\mathrm{Dy}$ have been confirmed and the yrast band extended up to ${10}^{+}$. A tentative candidate for the $4^{+}\to 2^{+}$ transition in ${}^{170}\mathrm{Dy}$ was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.

We use the wounded nucleon model to study the forward-backward multiplicity fluctuations measured by the PHOBOS Collaboration in Au $+$ Au collisions at $\sqrt{s_{{}_{\mathit{NN}}}}=200$ GeV. The enhancement of forward-backward fluctuations in Au $+$ Au collisions with respect to the elementary $p+p$ interactions is explained in this model by the asymmetric shape of the pseudorapidity density of produced particles from a single wounded nucleon and the fluctuations of the number of wounded nucleons in the colliding nuclei. The wounded nucleon model describes these experimental data better than the HIJING, AMPT, or UrQMD models do.

Semi-inclusive deep inelastic scattering on nuclear targets is an ideal tool to study the energy loss effect of an outgoing quark in a nuclear medium. By means of the short hadron formation time, the experimental data with quark hadronization occurring outside the nucleus are picked out. A leading-order analysis is performed for the hadron multiplicity ratios as a function of the energy fraction on helium, neon, and copper nuclei relative to deuteron for the various identified hadrons. It is shown that the nuclear effects on parton distribution functions can be neglected. It is found that the theoretical results considering the nuclear modification of fragmentation functions due to quark energy loss are in good agreement with the experimental data. Whether the quark energy loss is linear or quadratic with the path length is not determined. The obtained energy loss per unit length is $0.38\pm 0.03$ GeV/fm for an outgoing quark by the global fit.

We study coherent pion production in neutrino-nucleus scattering in the energy region relevant to neutrino oscillation experiments of current interest. Our approach is based on the combined use of the Sato-Lee model of electroweak pion production on a nucleon and the $\Delta$-hole model of pion-nucleus reactions. Thus we develop a model that describes pion-nucleus scattering and electroweak coherent pion production in a unified manner. Numerical calculations are carried out for the case of the ${}^{12}\mathrm{C}$ target. All the free parameters in our model are fixed by fitting to both total and elastic differential cross sections for $\pi$-${}^{12}\mathrm{C}$ scattering. Then we demonstrate the reliability of our approach by comparing our prediction for coherent pion photoproductions with the data. Finally, we calculate total and differential cross sections for neutrino-induced coherent pion production, and some of the results are compared with recent data from K2K, SciBooNE, and MiniBooNE. We also study the effect of nonlocality of $\Delta$ propagation in the nucleus and compare the elementary amplitudes used in different microscopic calculations.

The $2\nu \beta \beta$-decay running sums for ${}^{76}\mathrm{Ge}$ and ${}^{150}\mathrm{Nd}$ nuclei are calculated within a QRPA approach with account for deformation. A realistic nucleon-nucleon residual interaction based on the Brueckner $G$ matrix (for the Bonn CD force) is used. The influence of different model parameters on the functional behavior of the running sums is studied. It is found that the parameter $g_{\mathit{pp}}$ renormalizing the $G$ matrix in the QRPA particle-particle channel is responsible for a qualitative change in behavior of the running sums at higher excitation energies. For realistic values of $g_{\mathit{pp}}$ a significant negative contribution to the total $2\nu \beta \beta$-decay matrix element is found to come from the energy region of the giant Gamow-Teller resonance. This behavior agrees with results of other authors.

We discuss the effect of pairing on two-neutron space correlations in deformed nuclei. The spatial correlations are described by the pairing tensor in coordinate space calculated in the HFB approach. Calculations are done using the D1S Gogny force. We show that the pairing tensor has a rather small extension in the relative coordinate, a feature observed earlier in spherical nuclei. It is pointed out that in deformed nuclei the coherence length corresponding to the pairing tensor has a pattern similar to what we have found previously in spherical nuclei; that is, it is maximal in the interior of the nucleus and then it decreases rather rapidly in the surface region, where it reaches a minimal value of about 2 fm. This minimal value of the coherence length in the surface is essentially determined by the finite size properties of single-particle states in the vicinity of the chemical potential and has little to do with enhanced pairing correlations in the nuclear surface. It is shown that in nuclei the coherence length is not a good indicator of the intensity of pairing correlations. This feature is contrasted with the situation in infinite matter.

The $g$ factor of the ${}^{44}\mathrm{Cl}$ ground state is measured at the LISE fragment separator at the Grand Accélérateur National d’Ions Lourds (GANIL) using the $\beta$ nuclear magnetic resonance technique, resulting in $g$(${}^{44}\mathrm{Cl}$)$=(-)0.2749(2)$. An analysis of the $g$ factor value and of the theoretical level scheme in the shell-model framework reveals the presence of odd-proton $s_{1/2}$ configurations and neutron excitation across the $N=28$ shell gap in the ground state of ${}^{44}\mathrm{Cl}$. In addition, the measured $g$ factor strongly supports a $2^{-}$ spin assignment for the ${}^{44}\mathrm{Cl}$ ground state.

This work investigates the first correction to the equilibrium phase-space distribution and its effects on spectra and elliptic flow in heavy-ion collisions. We show that the departure from equilibrium on the freeze-out surface is the largest part of the viscous corrections to $v_2(p_T)$. However, the momentum dependence of the departure from equilibrium is not known a priori, and it is probably not proportional to $p_T^2$ as has been assumed in hydrodynamic simulations. At high momentum in weakly coupled plasmas, it is determined by the rate of radiative energy loss and is proportional to $p_T^{3/2}$. The weaker $p_T$ dependence leads to straighter $v_2(p_T)$ curves at the same value of viscosity. Furthermore, the departure from equilibrium is generally species dependent. A species-dependent equilibration rate, with baryons equilibrating faster than mesons, can explain “constituent quark scaling” without invoking coalescence models.

Hamiltonian light-front quantum field theory constitutes a framework for the nonperturbative solution of invariant masses and correlated parton amplitudes of self-bound systems. By choosing the light-front gauge and adopting a basis function representation, a large, sparse, Hamiltonian matrix for mass eigenstates of gauge theories is obtained that is solvable by adapting the ab initio no-core methods of nuclear many-body theory. Full covariance is recovered in the continuum limit, the infinite matrix limit. There is considerable freedom in the choice of the orthonormal and complete set of basis functions with convenience and convergence rates providing key considerations. Here we use a two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall anti-de Sitter/quantum chromodynamics (AdS/QCD) model obtained from light-front holography. We outline our approach and present illustrative features of some noninteracting systems in a cavity. We illustrate the first steps toward solving quantum electrodynamics (QED) by obtaining the mass eigenstates of an electron in a cavity in small basis spaces and discuss the computational challenges.

We investigate the $\gamma p\to K^{*+}\Lambda$ reaction within a Regge approach. For the gauge invariance of the scattering amplitude, we reggeize the $s$ channel and contact-term amplitudes as well as the $t$-channel amplitude. We obtain a decreasing behavior of the total cross section as the CLAS’s preliminary data show. We also calculate spin density matrices and find clear differences between our Regge model and the previous Feynman (isobar) model.

The production of ${}^{22}\mathrm{Na}$ in ONe novae can be influenced by the ${}^{22}\mathrm{Mg}$$(p,\gamma )$${}^{23}\mathrm{Al}$ reaction. To investigate this reaction rate at stellar energies, we have determined the asymptotic normalization coefficient (ANC) for ${}^{22}\mathrm{Mg}$$+p\to$${}^{23}\mathrm{Al}$ through measurements of the ANCs in the mirror nuclear system ${}^{22}\mathrm{Ne}$$+n\to$${}^{23}\mathrm{Ne}$. The peripheral neutron-transfer reactions ${}^{13}\mathrm{C}$(${}^{12}\mathrm{C}$,${}^{13}\mathrm{C}$)${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$(${}^{22}\mathrm{Ne}$,${}^{23}\mathrm{Ne}$)${}^{12}\mathrm{C}$ were studied. The identical entrance and exit channels of the first reaction make it possible to extract independently the ground-state ANC in ${}^{13}\mathrm{C}$. Our experiment gives $C_{p_{1/2}}^2$(${}^{13}\mathrm{C}$)$=2.24\pm 0.11$ fm${}^{-1}$, which agrees with the value obtained from several previous measurements. The weighted average for all the obtained $C_{p_{1/2}}^2$ is $2.31\pm 0.08$ fm${}^{-1}$. This value is adopted to be used in obtaining the ANCs in ${}^{23}\mathrm{Ne}$. The differential cross sections for the reaction ${}^{13}\mathrm{C}$(${}^{22}\mathrm{Ne}$,${}^{23}\mathrm{Ne}$)${}^{12}\mathrm{C}$ leading to the $J^{\pi }=5/2^{+}$ and $1/2^{+}$ states in ${}^{23}\mathrm{Ne}$ have been measured at 12 MeV/u. Optical model parameters for use in the DWBA calculations were obtained from measurements of the elastic scatterings ${}^{22}\mathrm{Ne}+{}^{13}\mathrm{C}$ and ${}^{22}\mathrm{Ne}+{}^{12}\mathrm{C}$. The extracted ANC for the ground state in ${}^{23}\mathrm{Ne}$, $C_{d_{5/2}}^2=0.86\pm 0.08\pm 0.12$ fm${}^{-1}$, is converted to its corresponding value in ${}^{23}\mathrm{Al}$ using mirror symmetry to give $C_{d_{5/2}}^2$(${}^{23}\mathrm{Al}$)$=(4.63\pm 0.77)\times {10}^3$ fm${}^{-1}$. The astrophysical $S$ factor $S(0)$ for the ${}^{22}\mathrm{Mg}$($p,\gamma$) reaction was determined to be $0.96\pm 0.11$ keV b. The consequences for nuclear astrophysics are discussed.

By employing a recently constructed hyperon-nucleon potential the equation of state of $\beta$-equilibrated and charge neutral nucleonic matter is calculated. The hyperon-nucleon potential is a low-momentum potential which is obtained within a renormalization group framework. Based on the Hartree-Fock approximation at zero temperature the densities at which hyperons appear in neutron stars are estimated. For several different bare hyperon-nucleon potentials and a wide range of nuclear matter parameters it is found that hyperons in neutron stars are always present. These findings have profound consequences for the mass and radius of neutron stars.

We use an ensemble of random but spin- and isospin-invariant interactions in a restricted orbital space as a tool for exploration of the shell-model parameter space to understand the source of collective effects. The mean field with the yrast state sequence $0^{+}-2^{+}-4^{+}$, rotational energy ratio $E(4^{+})/E(2^{+}),$ and rigid-rotor relation between the prolate quadrupole moment $Q(2^{+})$ and the transition probability $B(E2;2^{+}\to 0^{+})$ appears with a high probability as a result of mixing of single-particle orbitals split by deformation. For a given set of collective observables, we identify the responsible matrix elements of the effective forces. In this framework, we reanalyze an old problem of the predominance of prolate deformations among well-deformed nuclei.

We update our previous work on a Langevin-with-interaction model for charmonium in heavy-ion collisions by considering the effect owing to recombination. We determine the contribution to $J/\psi$ yields from $\mathrm{c̄}c$ pairs whose constituent quarks originate from two different hard processes. Like the surviving $J/\psi$ states, the recombinant $J/\psi$ also undergo both a stochastic interaction, determined by a hydrodynamical simulation of the heavy-ion collision, and an interaction determined by the $\mathrm{Q̄}Q$ potentials measured on the lattice for appropriate temperatures. From the results of these simulations, we determine both the direct and the recombinant contribution to the $J/\psi$ yields for RHIC conditions and find that, for central collisions, between 30% and 50% of the $J/\psi$ yield is caused by recombinant production. We compare our results with other models and look for how the recombinant contribution differs from the surviving contribution in the differential $p_T$ yields. Including the recombinant contribution improves the agreement with the latest analysis of charmonium at RHIC, which shows an absence of anomalous suppression except in the most central collisions.

Differential elliptic flow $v_2(p_T)$ for identified hadrons is investigated in the FAIR energy regime, employing a hadronic-string transport model (UrQMD) as well as a partonic transport model (AMPT). It is observed that both models show a mass ordering of $v_2$ at low $p_T$ and a switch-over resulting in a baryon-meson crossing at intermediate $p_T$. AMPT generates higher $v_2$ values compared to UrQMD. In addition, constituent quark number scaling behavior of elliptic flow is addressed. Scaling behavior in terms of the transverse momentum $p_T$ is found to be absent for both the partonic and the hadronic model. However, UrQMD and AMPT with a string melting scenario do exhibit an NCQ scaling of $v_2$ to varying degrees, with respect to the transverse kinetic energy ${\mathit{KE}}_T$. But the default AMPT, where partonic scatterings are not included, does not show any considerable scaling behavior. A variable $\alpha$ is defined to quantify the degree of ${\mathit{KE}}_T$ scaling. We found that UrQMD gives better scaling than AMPT at FAIR.

The saturation momentum seen in the nuclear infinite-momentum frame is directly related to transverse momentum broadening of partons propagating through the medium in the nuclear rest frame. Calculation of broadening within the color dipole approach, including the effects of saturation in the nucleus, gives rise to an equation which describes well the data on broadening in the Drell-Yan reaction and heavy quarkonium production.