It is shown that polarization transfer measurements $(\vec{e},e^{\prime }\vec{p})$ on a specific target nucleus can provide constraints on the ratio of the in-medium electric to magnetic form factor. Thereby one exploits the fact that proton knockout from single-particle levels exhibit a specific sensitivity to the effective nuclear density. It is shown that in ${}^{12}$C the effective nuclear density for $s$-shell knockout is about twice as high as for $p$-shell knockout. With current model predictions for the in-medium form factors, one obtains measurable modifications of the order of 5$\%$ in the ratios of the double polarization observables between those single-particle levels.

The recently developed “internal” density functional theory provides an existence theorem for a local potential that contains the center-of-mass correlations effects. The knowledge of the corresponding energy functional would provide a much more effective way than projection techniques to treat these correlations. The aim of this article is to construct such a functional. We propose a well-founded method, suitable for fermions as well as for bosons, which does not require any free parameters.

We present an analysis of the $\Lambda \left(1405\right)$ resonance produced in the reaction $p+p\to {\Sigma }^{\pm }+{\pi }^{\mp }+K^{+}+p$ at $3.5\mathrm{GeV}$ kinetic beam energy measured with the High Acceptance Dielectron Spectrometer (HADES) at the Gesellschaft für Schwerionenforschung (GSI). The two charged decay channels $\Lambda \left(1405\right)\to {\Sigma }^{\pm }{\pi }^{\mp }$ have been reconstructed for the first time in $p+p$ collisions. The efficiency and acceptance-corrected spectral shapes show a peak position clearly below $1400\mathrm{MeV}/{\mathrm{c}}^2$. We find a total production cross section of ${\sigma }_{\Lambda \left(1405\right)}=9.2\pm 0.9\pm 0.7_{-1.0}^{+3.3}\mu$b. The analysis of its polar angle distribution suggests that the $\Lambda \left(1405\right)$ is produced isotropically in the $p-p$ center-of-mass system (CMS).

Electromagnetic dipole transitions in ${}^{56}$Fe were measured in photon-scattering experiments with a linearly polarized photon beam. The parity quantum numbers of the excited dipole states were determined by the intensity asymmetry of resonantly scattered $\gamma$ rays with respect to the polarization plane of the incident photon beam. While the summed magnetic dipole ($M1$) strength was determined as $\Sigma B\left(M1\right)\uparrow =3.52\left(17\right)$ ${\mu }_N^2$ at excitation energies between 7 and 10 MeV, the summed electric dipole ($E1$) strength below 10 MeV was obtained as $\Sigma B\left(E1\right)\uparrow =78.0\left(15\right)\times {10}^{-3}$ $e^2$ fm${}^2$. The observed $M1$ strength was compared with shell-model predictions in the $pf$ shell using the GXPF1J and KB3G effective interactions. In addition, the $E1$ strength was compared with random-phase approximation calculations with the Skyrme interaction.

We present results from new spectral prompt $\gamma$-ray measurements from the spontaneous fission of ${}^{252}$Cf. Apart from one recent experiment, about four decades have passed since the last dedicated experiments were reported in the literature. Hence, there was a need for a revision. We have measured prompt fission $\gamma$ rays with both cerium-doped LaBr${}_3$ and CeBr${}_3$ scintillation detectors, both of which exhibit excellent timing and good energy resolution. The emission yield was determined to be ${\nu }_{\gamma }=(8.30\pm 0.08)$/fission and ${\nu }_{\gamma }=(8.31\pm 0.10)$/fission, with the average energy of ${\epsilon }_{\gamma }=(0.80\pm 0.01)$ MeV and ${\epsilon }_{\gamma }=(0.80\pm 0.01)$ MeV and total energy of $E_{\gamma ,\mathrm{tot}}=(6.64\pm 0.08)$ MeV and $E_{\gamma ,\mathrm{tot}}=(6.65\pm 0.12)$ MeV, with the LaBr${}_3$ and CeBr${}_3$ detectors, respectively. Since the results from the two detectors are in excellent agreement and confirm the historical data, but not those in the present evaluated nuclear data files, we strongly recommend an update.

Newly published ${}^{42}$Si $\gamma$-ray spectra and a final-state-inclusive ${}^{42}$Si production cross section value, obtained in a higher-statistics intermediate-energy two-proton removal experiment from ${}^{44}$S, are considered in terms of the final-state-exclusive cross sections computed using proposed shell-model effective interactions for nuclei near $N=28$. Specifically, we give cross section predictions when using the two nucleon amplitudes of the two-proton overlaps ${\langle }^{42}$Si$\left(J^{\pi }\right)|{}^{44}$S$\rangle$ computed using the newly proposed sdpf-mu shell-model Hamiltonian. We show that these partial cross sections or their longitudinal momentum distributions should enable a less-tentative interpretation of the measured gamma-ray spectra and provide a more quantitative assessment of proposed shell-model Hamiltonians in this interesting and challenging region of the chart of nuclides.

The meson production cross sections are estimated considering photon-photon interactions in hadron-hadron collisions at CERN Large Hadron Collider (LHC) energies. We consider a large number of mesons with photon-photon partial decay width well constrained by the experiment and some mesons which are currently considered as hadronic molecule and glueball candidates. Our results demonstrate that the experimental analysis of these states is feasible at the CERN LHC.

We study the kinetic and chemical equilibration in “infinite” parton matter within the parton-hadron-string dynamics off-shell transport approach, which is based on a dynamical quasiparticle model (DQPM) for partons matched to reproduce lattice QCD results—including the partonic equation of state—in thermodynamic equilibrium. The “infinite” parton matter is simulated by a system of quarks and gluons within a cubic box with periodic boundary conditions, at various energy densities, initialized out of kinetic and chemical equilibrium. We investigate the approach of the system to equilibrium and the time scales for the equilibration of different observables. We, furthermore, study particle distributions in the strongly interacting quark-gluon plasma (sQGP) including partonic spectral functions, momentum distributions, abundances of the different parton species, and their fluctuations (scaled variance, skewness, and kurtosis) in equilibrium. We also compare the results of the microscopic calculations with the ansatz of the DQPM. It is found that the results of the transport calculations are in equilibrium well matched by the DQPM for quarks and antiquarks, while the gluon spectral function shows a slightly different shape due to the mass dependence of the gluon width generated by the explicit interactions of partons. The time scales for the relaxation of fluctuation observables are found to be shorter than those for the average values. Furthermore, in the local subsystem, a strong change of the fluctuation observables with the size of the local volume is observed. These fluctuations no longer correspond to those of the full system and are reduced to Poissonian distributions when the volume of the local subsystem becomes small.

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios $(K^{+}+K^{-})/({\pi }^{+}+{\pi }^{-})$, $(p+\overline{p})/({\pi }^{+}+{\pi }^{-})$, and $(K^{+}+K^{-})/(p+\overline{p})$ are presented for Pb+Pb collisions at 158$A$ GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure ${\sigma }_{\text{dyn}}$, increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the $(K^{+}+K^{-})/({\pi }^{+}+{\pi }^{-})$ and $(p+\overline{p})/({\pi }^{+}+{\pi }^{-})$ ratio fluctuations. A description of the centrality and energy dependence of $(K^{+}+K^{-})/(p+\overline{p})$ ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.

The ground state of neutron-rich unbound ${}^{13}$Li was observed for the first time in a one-proton removal reaction from ${}^{14}$Be at a beam energy of 53.6 MeV/u. The ${}^{13}$Li ground state was reconstructed from ${}^{11}$Li and two neutrons giving a resonance energy of 120${}_{-80}^{+60}$ keV. All events involving single- and double-neutron interactions in the Modular Neutron Array (MoNA) were analyzed, simulated, and fitted self-consistently. The three-body (${}^{11}\text{Li}+n+n$) correlations within Jacobi coordinates showed strong dineutron characteristics. The decay energy spectrum of the intermediate ${}^{12}$Li system (${}^{11}\text{Li}+n$) was described with an $s$-wave scattering length of greater than $-4$ fm, which is a smaller absolute value than reported in a previous measurement.

Within a multiphase transport model, we investigate decorrelation of event planes over pseudorapidity and its effect on azimuthal anisotropy measurements in relativistic heavy-ion collisions. The decorrelation increases with increasing $\eta$ gap between particles used to reconstruct the event planes. The third harmonic event planes are found even anticorrelated between forward and backward rapidities, the source of which may root in the opposite orientation of the collision geometry triangularities. The decorrelation may call into question the anisotropic flow measurements with pseudorapidity gap designed to reduce nonflow contributions, hence the hydrodynamic properties of the quark-gluon plasma extracted from those measurements.

The ($n,\gamma$) reaction of the radioactive isotope ${}^{93}$Zr has been measured at the n_TOF high-resolution time-of-flight facility at CERN. Resonance parameters have been extracted in the neutron energy range up to 8 keV, yielding capture widths smaller (14$\%$) than reported in an earlier experiment. These results are important for detailed nucleosynthesis calculations and for refined studies of waste transmutation concepts.

With the aim of achieving a better and more complete understanding of neutrino interactions with nuclear targets, the coherent production of charged kaons induced by neutrinos and antineutrinos is investigated in the energy range of some of the current neutrino experiments. We follow a microscopic approach which, at the nucleon level, incorporates the most important mechanisms allowed by the chiral-symmetry-breaking pattern of QCD. The distortion of the outgoing $K$ ($\overline{K}$) is taken into account by solving the Klein-Gordon equation with realistic optical potentials. Angular and momentum distributions, as well as the energy and nuclear dependence of the total cross section, are studied.

Using a set of model equations of state satisfying the latest constraints from both terrestrial nuclear experiments and astrophysical observations, as well as state-of-the-art nuclear many-body calculations of the pure neutron matter equation of state, the tidal polarizability of canonical neutron stars in coalescing binaries is found to be a very sensitive probe of the high-density behavior of nuclear symmetry energy, which is among the most uncertain properties of dense neutron-rich nucleonic matter. Moreover, it changes less than $\pm 10\%$ by varying various properties of symmetric nuclear matter and symmetry energy around the saturation density within their respective ranges of remaining uncertainty.

Fragment yield data have been analyzed using the Landau free energy approach to investigate the critical phenomena of fragmenting quasi-projectiles formed in ${}^{64}\mathrm{Zn}+{}^{64}$Zn, ${}^{64}\mathrm{Ni}+{}^{64}$Ni, and ${}^{70}\mathrm{Zn}+{}^{70}$Zn reactions at beam energy of 35 MeV/nucleon. Pairing coefficients normalized to the temperature of the fragmenting source ($a_p/T$) were extracted from yield data of $N=Z$ fragments in order to correct for odd-even effects in free energy calculations. Plots of fragment free energy ($F/T$) versus the neutron-proton asymmetry show three minima, indicating the system to be in a first-order phase transition regime. Values of fitting parameters to the Landau free energy equation as well as $a_p/T$, which are related to thermodynamic properties of the fragmenting systems, exhibit a dependence on the neutron-proton asymmetry in addition to their dependence on the excitation energy of the fragmenting source.

Background: The $A=2$ and 3 form factors are among the observables of choice for testing models of nuclear interactions and associated electromagnetic charge and current operators. Here we investigate the validity of the chiral-effective-field-theory ($\chi$EFT) approach to describe the strong-interaction dynamics in these few-nucleon systems and their response to electromagnetic probes.

Purpose: The objectives of the present work are twofold. The first is to address and resolve some of the differences present in independent, $\chi$EFT derivations up to one loop, recently appearing in the literature, of the nuclear charge and current operators. The second objective is to provide a complete set of $\chi$EFT and hybrid predictions for the structure functions and tensor polarization of the deuteron, for the charge and magnetic form factors of ${}^3$He and ${}^3$H, and for the charge and magnetic radii of these few-nucleon systems.

Methods: The calculations use wave functions derived from either chiral or conventional two- and three-nucleon potentials and Monte Carlo methods to evaluate the relevant matrix elements.

Results: In reference to the two objectives mentioned earlier, we find that (i) there are no differences between the $\chi$EFT magnetic dipole operator at one loop derived in our formalism and that obtained by Kölling et al. [Phys. Rev. C 80, 045502 (2009)] with the unitary transformation method and (ii) there is excellent agreement between theory and experiment for the static properties and elastic form factors of these $A=2$ and 3 nuclei up to momentum transfers $q\lesssim 2.0$–2.5 fm${}^{-1}$. A complete analysis of the results is provided.

Conclusions: Nuclear $\chi$EFT provides a very satisfactory description of the isoscalar and isovector charge and magnetic structure of the $A=2$ and 3 nuclei at low momentum transfers $q\lesssim 3m_{\pi }$. In particular, contributions from two-body charge and current operators are crucial for bringing theory into close agreement with experiment. At higher $q$ values the present $\chi$EFT predictions are similar to those obtained in the hybrid approach, as well as in older studies based on the conventional meson-exchange picture, and fail to reproduce the measured $A=2$ and 3 form factors in the diffraction region.

Pygmy and giant dipole resonance (PDR and GDR) in Ni isotopes have been investigated by Coulomb excitation in the framework of the isospin-dependent quantum molecular dynamics model (IQMD). The spectra of $\gamma$ rays are calculated and the peak energy, the strength and full width at half maximum (FWHM) of GDR and PDR have been extracted. Their sensitivities to nuclear equation of state, especially to its symmetry energy term are also explored. By a comparison with the other mean-field calculations, we obtain the reasonable values for symmetry energy and its slope parameter at saturation, which gives an important constrain for IQMD model. In addition, we also studied the neutron excess dependence of GDR and PDR parameters for Ni isotopes and found that the energy-weighted sum rule (EWSR) ${\mathrm{PDR}}_{m_1}/{\mathrm{GDR}}_{m_1}\%$ increases linearly with the neutron excess.

$B_c$ meson production in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s}=2.76$$A\text{TeV}$ is surveyed in both a statistical coalescence model and a transport model. The nuclear modification factor $R_{AA}$ is predicted to be between 2 and 18 in the most central collisions, which can help to confirm the regeneration mechanism. In addition, the momentum dependence is also investigated as given by the transport model. A strong suppression of the transverse momentum is found in central collisions accompanying the enhancement in yield. The spectrum and elliptic flow of $B_c$ are also discussed.