The inclusive ${}^{93}\mathrm{Nb}$($\vec{p},\alpha$) reaction to the continuum was investigated at an incident energy of 160 MeV. Emission-energy angular distributions for cross sections as well as analyzing powers were explored. A range of scattering angles from 15${}^{\circ }$ to 60${}^{\circ }$ (lab.) was covered and $\alpha$-particle emission energies from $\approx$30 MeV to the kinematic limit were measured. As in our earlier work, the experimental distributions were compared with a multistep direct theory combined with a knockout reaction mechanism as the terminating step in the $\alpha$-particle emission. Reasonable agreement between the theoretical predictions and the experimental double-differential cross section and analyzing-power angular distributions were obtained.

Despite the fact that a system created in relativistic heavy ion collisions is an isolated quantum system, which cannot increase its entropy in the course of unitary quantum evolution, hydrodynamical analysis of experimental data seems to indicate that the matter formed in the collisions is thermalized very quickly. Based on common consideration of hydrodynamics as an effective theory in the domain of slow- and long-length modes, we discuss the physical mechanisms responsible for the decoherence and emergence of the hydrodynamic behavior in such collisions, and demonstrate how such physical mechanisms work in the case of the scalar field model. We obtain the evolution equation for the Wigner function of a long-wavelength subsystem that describes its decoherence, isotropization, and approach to thermal equilibrium induced by interaction with short-wavelength modes. Our analysis supports the idea that decoherence, quantum-to-classical transition, and thermalization in isolated quantum systems are attributed to the experimental context, and are related to a particular procedure of decomposition of the whole quantum system into relevant and irrelevant from an observational viewpoint subsystems.

Initial conditions are required to solve medium modified Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (mDGLAP) evolution equations for modified fragmentation functions due to multiple scatterings and parton energy loss. Such initial conditions should in principle include energy loss for partons at scale $Q_0$ above which mDGLAP evolution equations can be applied. Several models for the initial condition motivated by induced gluon bremsstrahlung in perturbative QCD are used to calculate the modified fragmentation functions in nuclear medium and to extract the jet transport parameter $\widehat{q}$ from fits to experimental data in deeply inelastic scattering (DIS) off nuclei. The model with a Poisson convolution of multiple gluon emissions is found to provide the overall best ${\chi }^2$/d.o.f. fit to the HERMES data and gives a value of ${\widehat{q}}_0\approx 0.020\pm 0.005$ GeV${}^2$/fm at the center of a large nucleus.

Coulomb breakup at high energy in inverse kinematics of proton-rich ${}^{31}\mathrm{Cl}$ was used to constrain the thermonuclear ${}^{30}\mathrm{S}$($p,\gamma$)${}^{31}\mathrm{Cl}$ capture reaction rate under typical Type I x-ray burst conditions. This reaction is a bottleneck during rapid proton-capture nucleosynthesis (rp process), where its rate depends predominantly on the nuclear structure of ${}^{31}\mathrm{Cl}$. Two low-lying states just above the proton-separation threshold of $S_p=296\left(50\right)$ keV in ${}^{31}\mathrm{Cl}$ have been identified experimentally using the R${}^3$B-LAND setup at the GSI Helmholtzzentrum für Schwerionenforschung GmbH. Both states are considered to play a key role in the thermonuclear ${}^{30}\mathrm{S}$($p,\gamma$)${}^{31}\mathrm{Cl}$ capture reaction. Excitation energies of the first $J^{\pi }=1/2^{+},5/2^{+}$ states have been extracted and the reaction rate for proton capture on ${}^{30}\mathrm{S}$ under typical rp-process temperatures has been investigated.

We present a microscopic description of nuclei in the intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through 15 major shells to accommodate particle excitations, which appear critical to highly deformed spatial structures and the convergence of associated observables.

Photofission experiments were performed on targets of ${}^{232}\mathrm{Th}$, ${}^{233,235,238}\mathrm{U},$ ${}^{237}\mathrm{Np}$, and ${}^{239,240}\mathrm{Pu}$ using nearly 100% linearly polarized, high intensity ($\sim 5\times {10}^6\gamma /$s), and nearly-monoenergetic $\gamma$-ray beams having energies between 5.3 and 7.6 MeV at the High Intensity $\gamma$-ray Source (HI$\gamma$S) located at Duke University and Triangle Universities Nuclear Laboratory. An array of 12–18 liquid scintillator detectors was used to measure prompt fission neutron yields parallel and perpendicular to the plane of beam polarization. Polarization asymmetries, the differences between the in-plane and out-of-plane yields divided by their sums, were measured. Asymmetries close to zero were found for ${}^{233,235}$U, ${}^{237}\mathrm{Np}$, and ${}^{239}$Pu while significant asymmetries ($\sim$0.2–0.5) were found for ${}^{232}\mathrm{Th}$, ${}^{238}$U, and ${}^{240}$Pu. Predictions based on previously measured photofission fragment angular distributions combined with a model of prompt neutron emission agree well with the experimental results.

We calculate the centrality dependence of direct photons produced in Au+Au collisions at the invariant collision energy $\sqrt{s_{NN}}=200$ GeV and their transverse momentum spectra within the parton-hadron-string dynamics transport approach. As sources for “direct” photons, we incorporate the interactions of quarks and gluons as well as hadronic interactions ($\pi +\pi \to \rho +\gamma$, $\rho +\pi \to \pi +\gamma$, meson-meson bremsstrahlung $m+m\to m+m+\gamma$, and meson-baryon bremsstrahlung $m+B\to m+B+\gamma$), the decays of $\varphi$ and $a_1$ mesons, and the photons produced in the initial hard collisions. We find that the transverse momentum $p_T$ spectra of the “thermal” photons (i.e., the direct photons after the pQCD contribution is subtracted) deviate from exponential distributions and, consequently, observe a strong dependence of the inverse slope parameter $T_{\mathrm{eff}}$ on the fitting range in $p_T$. On the other hand, all the obtained “effective temperatures” are well above the critical temperature for the deconfinement phase transition even for peripheral collisions, reflecting primarily a “blue shift” due to radial collective motion of hadrons. Our calculations suggest that the channel decomposition of the observed spectrum changes with centrality with an increasing (dominant) contribution of hadronic sources for more peripheral reactions. Furthermore, the thermal photon yield is found to scale roughly with the number of participant nucleons as $N_{\mathrm{part}}^{\alpha }$ with $\alpha \approx$ 1.5, whereas the partonic contribution scales with an exponent ${\alpha }_p\approx 1.75$. Additionally, we provide predictions for the centrality dependence of the direct photon elliptic flow $v_2\left(p_T\right)$. The photons from the hot deconfined matter in the early stages of the collision carry a much smaller elliptic flow than the final hadrons. Consequently, the direct photon $v_2$ in the most central bin is of the order of a few percent. On the other hand, the elliptic flow of direct photons is considerably larger in more peripheral collisions, approaching that of hadrons.

A compilation of recently measured STAR data for elliptic flow ($v_2$) of $\varphi$ mesons in the Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan program and comparison with a multiphase transport model (AMPT) are presented. The experimental data at $\sqrt{s_{NN}}$ $\ge$ 19.6 GeV agree well with the string melting version of the AMPT model. The model includes partonic interactions and quark coalescence as a mechanism of hadronization. This indicates that there is a substantial contribution to collectivity from partonic interactions at $\sqrt{s_{NN}}$ $\ge$ 19.6 GeV. The measured $\varphi$-meson $v_2$ at $\sqrt{s_{NN}}$ = 7.7 and 11.5 GeV are found to be smaller than those obtained from the AMPT model without partonic interactions. This indicates negligible contribution of partonic collectivity to the observed $\varphi$-meson $v_2$ at $\sqrt{s_{NN}}$ $\le$ 11.5 GeV.

We study the electric conductivity as well as the magnetic response of hot QCD matter at various temperatures $T$ and chemical potentials ${\mu }_q$ within the off-shell parton–hadron–string dynamics transport approach for interacting partonic systems in a finite box with periodic boundary conditions. The response of the strongly interacting system in equilibrium to an external electric field defines the electric conductivity ${\sigma }_0$, whereas the response to a moderate external magnetic field defines the induced diamagnetic moment ${\mu }_L$ ($T,{\mu }_q$) as well as the spin susceptibility ${\chi }_S(T,{\mu }_q)$. We find a sizable temperature dependence of the dimensionless ratio ${\sigma }_0/T$ well in line with calculations in a relaxation time approach for $T_c<T<2.5T_c$ as well as an increase of ${\sigma }_0$ with ${\mu }_q^2/T^2$. Furthermore, the frequency dependence of the electric conductivity $\sigma \left(\Omega \right)$ shows a simple functional form well in line with results from the dynamical quasiparticle model. The spin susceptibility ${\chi }_S(T,{\mu }_q)$ is found to increase with temperature $T$ and to rise $\sim$${\mu }_q^2/T^2$ too. The actual values for the magnetic response of the QGP in the temperature range below 250 MeV show that the QGP should respond diamagnetically in actual ultrarelativistic heavy-ion collisions since the maximal magnetic fields created in these collisions are smaller than $B_c\left(T\right)$, which defines a boundary between diamagnetism and paramagnetism.

Mirror energy differences (MEDs) and triplet energy differences (TEDs) in the $T=1$ analogue states are important probes of isospin-symmetry breaking. Inspired by the recent spectroscopic data of ${}^{66}$Se, we investigate these quantities for $A=66–78$ nuclei with large-scale shell-model calculations. For the first time, we find clear evidence suggesting that the isospin nonconserving (INC) nuclear force has a significant effect for the upper $fp$ shell region. Detailed analysis shows that, in addition to the INC force, the electromagnetic spin-orbit interaction plays an important role for the large, negative MED in $A=66$ and 70 and the multipole Coulomb term contributes to the negative TED in all the $T=1$ triplet nuclei. The INC force and its strength needed to reproduce the experimental data are compared with those from the $G$-matrix calculation using the modern charge-dependent nucleon-nucleon forces.

The shapes of neutron-rich exotic Ni isotopes are studied. Large-scale shell model calculations are performed by the advanced Monte Carlo shell model (MCSM) for the $pf$-$g_{9/2}$-$d_{5/2}$ model space. Experimental energy levels are reproduced well by a single fixed Hamiltonian. Intrinsic shapes are analyzed for MCSM eigenstates. Intriguing interplays among spherical, oblate, prolate, and $\gamma$-unstable shapes are seen, including shape fluctuations, E(5)-like situations, the magicity of doubly magic ${}^{56,68,78}$Ni, and the coexistence of spherical and strongly deformed shapes. Regarding the last point, strong deformation and change of shell structure can take place simultaneously, being driven by the combination of the tensor force and changes of major configurations within the same nucleus.

The problem of determining completely the spin amplitudes of photoproduction of two pseudoscalar mesons on a nucleon from observables is studied. The procedure of reconstruction of the scattering matrix elements from a complete set of observables is based on the expressions of all observables as quadratic Hermitian forms in the reaction matrix elements which are derived explicitly. Their inversion allows one to find explicit solutions for the reaction matrix elements in terms of observables. Two methods for finding a complete set of observables are presented. In particular, one set was found that does not contain a triple polarization observable.

Background: Nuclei in the $Z\approx 100$ mass region represent the heaviest systems where detailed spectroscopic information is experimentally available. Although microscopic-macroscopic and self-consistent models have achieved great success in describing the data in this mass region, a fully satisfying precise theoretical description is still missing.

Purpose: By using fine-tuned parametrizations of the energy density functionals, the present work aims at an improved description of the single-particle properties and rotational bands in the nobelium region. Such locally optimized parametrizations may have better properties when extrapolating towards the superheavy region.

Methods: Skyrme Hartree-Fock-Bogolyubov and Lipkin-Nogami methods were used to calculate the quasiparticle energies and rotational bands of nuclei in the nobelium region. Starting from the most recent Skyrme parametrization, UNEDF1, the spin-orbit coupling constants and pairing strengths have been tuned, so as to achieve a better agreement with the excitation spectra and odd-even mass differences in ${}^{251}$Cf and ${}^{249}$Bk.

Results: The quasiparticle properties of ${}^{251}$Cf and ${}^{249}$Bk were very well reproduced. At the same time, crucial deformed neutron and proton shell gaps open up at $N=152$ and $Z=100$, respectively. Rotational bands in Fm, No, and Rf isotopes, where experimental data are available, were also fairly well described. To help future improvements towards a more precise description, small deficiencies of the approach were carefully identified.

Conclusions: In the $Z\approx 100$ mass region, larger spin-orbit strengths than those from global adjustments lead to improved agreement with data. Puzzling effects of particle-number restoration on the calculated moment of inertia, at odds with the experimental behavior, require further scrutiny.

Odd-odd ${}^{138}$La nuclei have been produced in the ${}^{12}$C+${}^{238}$U fusion-fission reaction and their $\gamma$ rays studied with the Euroball array. The high-spin level scheme has been built up to $\sim$4.5 MeV excitation energy and spin $I\sim 16\hslash$ from the triple $\gamma$-ray coincidence data. An isomeric state lying at 739-keV excitation energy has been identified. The configurations of the structures are first discussed by analogy with the proton excitations identified in the semimagic ${}^{139}$La${}_{82}$ nucleus, which involve the three high-$j$ orbits lying above the $Z=50$ gap, $\pi g_{7/2}$, $\pi d_{5/2}$, and $\pi h_{11/2}$. The competition of these three orbits to produce the yrast line is confirmed by the results of shell-model calculations performed in this work.

$\beta$-decay properties of neutron-rich Zr and Mo isotopes are investigated within a microscopic theoretical approach based on the proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual separable particle-hole and particle-particle forces are also included in the formalism. The structural evolution in these isotopic chains including both even and odd isotopes is analyzed in terms of the equilibrium deformed shapes. Gamow-Teller strength distributions, $\beta$-decay half-lives, and $\beta$-delayed neutron-emission probabilities are studied, stressing their relevance to describe the path of the nucleosynthesis rapid neutron capture process.

A simple form of nonlinear self-coupling of the scalar meson field is introduced and suggests a new nucleon-nucleon ($NN$) potential in relativistic mean field theory (RMFT) analogous to the M3Y interaction. We investigate the ability of RMFT to reproduce nuclear ground state properties and the surface phenomena like proton radioactivity simultaneously with the proposed $NN$ interaction. The results obtained agree reasonably well with the widely used M3Y $NN$ interactions and the experimental data in this first application of nucleon-nucleon potential.

It has been shown recently that taking into account strong, weak, electromagnetic, and gravitational interactions, and fulfilling the global charge neutrality of the system, a transition layer will happen between the core and crust of neutron stars, at the nuclear saturation density. We use relativistic mean field theory together with the Thomas-Fermi approximation to study the detailed structure of this transition layer and calculate its surface and Coulomb energy. We find that the surface tension is proportional to a power-law function of the baryon number density in the core bulk region. We also analyze the influence of the electron component and the gravitational field on the structure of the transition layer and the value of the surface tension, to compare and contrast with known phenomenological results in nuclear physics. Based on the above results we study the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. Assuming the core-crust transition at nuclear density ${\rho }_{\mathrm{core}}\approx 2.7\times {10}^{14}$ g cm${}^{-3}$, we find that the instability sets the upper limit to the crust density, ${\rho }_{\mathrm{crust}}^{\mathrm{crit}}\approx 1.2\times {10}^{14}$ g cm${}^{-3}$. This result implies a nonzero lower limit to the maximum electric field of the core-crust transition surface and makes inaccessible a limit of quasilocal charge neutrality in the limit ${\rho }_{\mathrm{crust}}={\rho }_{\mathrm{core}}$. The general framework presented here can be also applied to study the stability of sharp phase transitions in hybrid stars as well as in strange stars, both bare and with outer crust. The results of this work open the way to a more general analysis of the stability of these transition surfaces, accounting for other effects such as gravitational binding, centrifugal repulsion, magnetic field induced by rotating electric field, and therefore magnetic dipole-dipole interactions.

We study inelastic neutrino scattering off hot nuclei for temperatures relevant under supernova conditions. The method we use is based on the quasiparticle random phase approximation extended to finite temperatures within the thermo-field dynamics. The method allows a transparent treatment of upward and downward transitions in hot nuclei, avoiding the application of Brink's hypothesis. For the sample nuclei ${}^{56}$Fe and ${}^{82}$Ge we perform a detailed analysis of thermal effects on the strength distributions of allowed Gamow-Teller (GT) transitions which dominate the scattering process at low neutrino energies. For ${}^{56}$Fe and ${}^{82}$Ge the finite temperature cross sections are calculated by taking into account the contribution of allowed and forbidden transitions. The observed enhancement of the cross section at low neutrino energies is explained by considering thermal effects on the GT strength. For ${}^{56}$Fe we compare the calculated cross sections to those obtained earlier from a hybrid approach that combines large-scale shell-model and RPA calculations.

We calculate the scattering rate of low-energy neutrinos in hot and dense neutron matter encountered in neutrons stars and supernovae in the hydrodynamic regime. We find that the Brillouin peak, associated with the sound mode, and the Rayleigh peak, associated with the thermal diffusion mode, dominate the dynamic structure factor. Although the total scattering cross section is constrained by the compressibility sum rule, the differential cross section calculated using the hydrodynamic response function differs from results obtained in approximate treatments often used in astrophysics such as random phase approximations. We identified these differences and discuss their implications for neutrino transport in supernovae.

Spallation cross sections from thin natural copper and iron targets bombarded by a mixed 120 GeV/c proton/pion beam were measured in an activation experiment at CERN. The beam intensity was monitored by a calibrated ionization chamber and the activity of several spallation products was measured (14 for copper and 16 for iron) by γ spectrometry, allowing the absolute cross section of the mixed hadron beam to be derived. Monte Carlo simulations with the FLUKA code provided the ratio between the proton- and pion-induced reaction cross sections for a given spallation product, allowing us to extrapolate the individual cross sections for the proton- and the pion-induced reactions. Where possible the values were compared with literature data and showed to be generally in agreement with the highest energy data available.