As a new observable for heavy flavor correlations the momentum imbalance $A_D$ of $D$ mesons is proposed. It is defined analogously to the jet momentum imbalance $A_J$ of fully reconstructed jets. However, because $D$ mesons are flavor-tagged particles, no jet reconstruction is necessary. $A_D$ quantifies the influence of the medium created in heavy-ion collisions on correlated charm pairs. We present results with the partonic transport model Boltzmann approach to multiparton scatterings, which describes well the nuclear modification factor and elliptic flow of all heavy flavor particles at BNL Relativistic Heavy Ion Collider and Large Hadron Collider (LHC). The $A_D$ distribution in heavy-ion collisions at LHC is shifted to larger values of $A_D$ compared to proton-proton collisions. We argue that this shift is attributable to medium effects and can be explained partially by a path-length imbalance of charm pairs and partially by momentum fluctuations in the initial charm-pair distribution.

One of the main goals of the study of high transverse momentum ($P_T$) observables in the context of ultrarelativistic heavy-ion collisions is the determination of properties of QCD matter. In particular, the transport coefficients $\widehat{q}$ and $\widehat{e}$ characterizing the interaction of the medium with a high $p_T$ parton are accessible via hard probes. However, a precision extraction of their temperature dependence from current data faces the problem that neither the space-time geometry of the evolving matter nor the link between thermodynamics and transport coefficients is unambiguously known. Thus, various conjectured scenarios exist for how thermodynamics and transport coefficients behave close to the phase transition. While often a behavior with the energy density $\widehat{q}\sim {\epsilon }^{3/4}$ is assumed, leading to a decrease of the scaled $\widehat{q}\left(T\right)/T^3$ close to the critical temperature $T_C$, other scenarios expect instead a near $T_C$ enhancement of jet quenching. In this work, the response of both the extraction of $\widehat{q}$ and the enhancement of $v_2$ at high $P_T$ to modification of jet quenching close to $T_C$ is investigated within yajem, a well-tested in-medium shower evolution Monte Carlo code, embedded into a fluid dynamics simulation for the medium, thus allowing a gauge of the magnitude of the effect in a realistic framework.

We study the three-body systems of ${}^3\mathrm{He}$ and $pd$ scattering and demonstrate, both analytically and numerically, that a new $pd$ three-body force is needed at next-to-leading order in pionless effective field theory. We also show that at leading order these observables require no new three-body force beyond what is necessary to describe $nd$ scattering. We include electromagnetic effects by iterating only diagrams that involve a single photon exchange in the three-body sector.

We investigate the thermal properties of the potential model equation of state of Akmal, Pandharipande, and Ravenhall. This equation of state approximates the microscopic model calculations of Akmal and Pandharipande, which feature a neutral pion condensate. We treat the bulk homogeneous phase for isospin asymmetries ranging from symmetric nuclear matter to pure neutron matter and for temperatures and densities relevant for simulations of core-collapse supernovae, protoneutron stars, and neutron star mergers. Numerical results of the state variables are compared with those of a typical Skyrme energy density functional with similar properties at nuclear densities but which differ substantially at supranuclear densities. Analytical formulas, which are applicable to nonrelativistic potential models such as the equations of state we are considering, are derived for all state variables and their thermodynamic derivatives. A highlight of our work is its focus on thermal response functions in the degenerate and nondegenerate situations, which allow checks of the numerical calculations for arbitrary degeneracy. These functions are sensitive to the density-dependent effective masses of neutrons and protons, which determine the thermal properties in all regimes of degeneracy. We develop the “thermal asymmetry free energy” and establish its relation to the more commonly used nuclear symmetry energy. We also explore the role of the pion condensate at supranuclear densities and temperatures. Tables of matter properties as functions of baryon density, composition (i.e., proton fraction), and temperature are being produced which are suitable for use in astrophysical simulations of supernovae and neutron stars.

In this Rapid Communication we point out strong correlations between the Garvey-Kelson mass relations (GKs). These correlations are originated from the statistical odd-even feature of the interaction between the last proton and the last neutron in atomic nuclei and are instructive in reducing the deviations of the GKs in applications.

An extensive investigation on the α decay properties of the isotopes of the superheavy nuclei with $Z$ = 118, within the range 271 $\le A\le$ 310, has been performed within the Coulomb and proximity potential model for deformed nuclei. The α decay half-lives of ${}^{294}118$ and its decay products, evaluated using our formalisms, are in good agreement with the experimental results. The calculated α half-lives were also found to be matching well with the values computed using the Viola-Seaborg systematic, the universal curve of Poenaru et al. [Phys. Rev. C 83, 014601 (2011);Phys. Rev. C 85, 034615 (2012)] and the analytical formulas of Royer [J. Phys. G: Nucl. Part. Phys. 26, 1149 (2000)]. So as to identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated for all the isotopes under study and, our prediction of 3α chains from ${}^{294}118$ go hand in hand with the experimental observations. Our study also unveils that those isotopes of $Z$ = 118 with $A$ ≥ 301 and with $A\le$ 275 do not survive fission, thus restricting the α decay within the range of 276 $\le A\le$ 300, and we hope that the theoretical prediction of 5α decay chains consistently from ${}^{289-293}118$ isotopes provides a new perspective to experimentalists.

I developed a dynamical model devoted to studying the cooling of a quark-antiquark plasma and its hadronization into mesons and baryons. To perform this modeling, I considered the Nambu–Jona-Lasinio (NJL) model, completed by the inclusion of a Polyakov loop, to form the PNJL model. I studied the mesonization, but also the baryonization of this system, thanks to cross sections calculated according to $\sqrt{s},$ the temperature, and the densities. In the performed simulations, I identified the dominant reactions. I also underlined the existence of a remote interaction between quarks. A purpose of this paper was to compare the NJL and PNJL results to see if one of these two models can make it possible to obtain a full hadronization of an open system initially composed of quarks and antiquarks.

The electric quadrupole transition rates for the high-spin yrast states of ${}^{104}$Pd have been measured by using the Doppler-shift attenuation method. These values decrease with the increase of angular momentum, which can be associated with the phenomenon of antimagnetic rotation. In the present work, a numerical calculation based on the semiclassical particle plus rotor model for antimagnetic rotation has been employed, giving a good description of the experimental Routhian and the transition rates and providing conclusive evidence of antimagnetic rotation in a nucleus other than cadmium.

Using the covariant spectator theory (CST), one boson exchange models have been found that give precision fits to low-energy $np$ scattering and the deuteron binding energy. The boson-nucleon vertices used in these models contain a momentum dependence that requires a new class of interaction currents for use with electromagnetic interactions. Current conservation requires that these new interaction currents satisfy a two-body Ward-Takahashi identity, and using principals of simplicity and picture independence, these currents can be uniquely determined. The results lead to general formulas for a two-body current that can be expressed in terms of relativistic $np$ wave functions, $\Psi$, and two convenient truncated wave functions, ${\Psi }^{\left(2\right)}$ and $\widehat{\Psi }$, which contain all of the information needed for the explicit evaluation of the contributions from the interaction current. These three wave functions can be calculated from the CST bound- or scattering-state equations (and their off-shell extrapolations). A companion paper uses this formalism to evaluate the deuteron magnetic moment.

The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high-precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents, which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small P-state components gives 0.864(2). These are about 1% larger than the measured value of the moment, 0.857 n.m., giving a new CST prediction for the size of the $\rho \pi \gamma$ exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulas for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.

I have proposed two parameter sets, NLD1 and NLD2, for the Lagrangian with nonlinear derivative couplings in the relativistic mean-field theory. Properties of nuclear matter and finite nuclei are explored. It is shown that this Lagrangian model can lead to a softening of the equation of state and symmetry energy at high densities. Two trends for the high-density behavior of symmetry energy are obtained with NLD1 and NLD2. These two sets also give a much less repulsive Schrödinger equivalent optical potential at high nucleon energies compared to standard relativistic mean-field models and reproduce the experimental data very well. The study also shows that a good description of ground-state properties of nuclei is achieved with this Lagrangian.

Background: Two-photon emission, while well known in atomic physics, is a rare second-order process in nuclear physics with only three cases where a two-photon branch is measured. The limited knowledge stems from the experimental difficulty in resolving two-photon emission from dominant single-photon emission, restricting practical cases for study to $0^{+}\to 0^{+}$ ($E0$) transitions, since single-photon emission is forbidden. In practical terms, this limits the range of easily accessible cases to even-even nuclei with the unusual property of a first excited state with spin/parity of 0${}^{+}$.

Purpose: Two-photon branches are measured for the closed-shell nuclei, ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, and ${}^{90}\mathrm{Zr}$. The intention of the present work was to obtain data for a case which was not a closed-shell nucleus. Of the possible nuclei relevant to such a study, ${}^{98}Mo$ was chosen as its first-excited state is 0${}^{+}$ and lies below 1 MeV, meaning that internal pair transitions are not allowed.

Method: The first excited state ($J^{\pi }=0^{+}$) in ${}^{98}Mo$ was excited in resonant inelastic proton scattering using a 6.7-MeV proton beam. The population of the state was selected using an annular double-sided silicon strip detector (DSSD). The decay of the state by conversion electrons was observed using the same DSSD, while Gammasphere was used to detect possible two-photon events.

Results: An upper limit on the two-photon branch obtained was 1 $\times$ 10${}^{-4}$ at the 95% confidence level (CL). Conclusions The upper limit obtained is smaller than any other previously obtained two-photon branch. Phase space considerations suggest that the actual value of the branching ratio in this case may be significantly smaller than the upper limit obtained.

We present a study of the 1+1 flavor system of strongly interacting matter in terms of the Polyakov–Nambu–Jona-Lasinio model. We find that, although the small isospin-symmetry breaking brought in through unequal light quark masses is too small to affect the thermodynamics of the system in general, it may have a significant effect in baryon-isospin correlations and have a measurable impact in heavy-ion collision experiments.

We perform a global analysis of all available electron-deuteron ($ed$) quasielastic scattering data using $Q^2$-dependent smearing functions that describe inclusive inelastic $ed$ scattering within the weak-binding approximation. We study the dependence of the cross sections on the deuteron wave function and the off-shell extrapolation of the elastic electron-nucleon cross sections, which show particular sensitivity at $x\gg 1$. The excellent overall agreement with data over a large range of $Q^2$ and $x$ suggests a limited need for effects beyond the impulse approximation, with the exception of the very high-$x$ and very low-$Q^2$ regions, where short-range meson exchange and final state interaction effects become more relevant.

The structure of the three-body $nn\Lambda$ system, which has been observed recently by the HypHI Collaboration, is investigated taking $\Lambda N$-$\Sigma N$ coupling explicitly into account. The $YN$ and $NN$ interactions employed in this work reproduce the binding energies of ${}_{\Lambda }{}^3\mathrm{H}$, ${}_{\Lambda }{}^4\mathrm{H}$, and ${}_{\Lambda }{}^4\mathrm{He}$. We do not find any ${}_{\Lambda }{}^{3}n$ bound state, which contradicts the interpretation of the data reported by the HypHI Collaboration.

The question of the sudden increase of collectivity in neutron-rich nuclei when approaching $N=40$ has recently interested both experimentalists and theorists. In this paper we study the development of collectivity along the chromium and iron isotopic chains. The calculations are performed within two different perspectives, namely, the proton-neutron interacting boson model (IBM-2) and interacting shell model (ISM) and compared with the available experimental data. The onset of collectivity is studied through nuclear quantities and observables that suggest differences in the nuclear structure of Cr and Fe isotopical chains. Furthermore, a prediction for the shape transition from a spherical vibrator to $\gamma$-soft rotor with nucleus ${}^{58}$Cr standing at the critical point is discussed.

The elliptic flows of thermal dielectrons are investigated within a (2+1)-dimension event-by-event hydrodynamic model for Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. The fluctuating initial conditions are given by the Monte Carlo Glauber model. We find in our event-by-event calculation rather weak correlation between the dilepton emission angles and the event plane angles of charged hadrons. We observe strong fluctuation effects in dilepton elliptic flows when using the event plane angles of dileptons at specific invariant mass $M$. The correlation between the dilepton event plane angle and charged hadron one becomes stronger with decreasing $M$. This provides a possible measure of the interplay between the effect of geometric deformation and that of fluctuating “hot spots” in relativistic heavy ion collisions.

Experimental transverse momentum spectra of identified particles in $p$-Pb collisions at 5.02 TeV show many similarities to the corresponding Pb-Pb results, the latter ones usually being interpreted in terms of hydrodynamic flow. We analyze these data using epos3, an event generator based on a $3\mathrm{D}+1$ viscous hydrodynamical evolution starting from flux-tube initial conditions, which are generated in the Gribov-Regge multiple scattering framework. An individual scattering is referred to as Pomeron, identified with a parton ladder, eventually showing up as flux tubes (or strings). Each parton ladder is composed of a perturbative QCD hard process, plus initial- and final-state linear parton emission. Nonlinear effects are considered by using saturation scales $Q_s$, depending on the energy and the number of participants connected to the Pomeron in question. We compute transverse momentum ($p_t$) spectra of pions, kaons, protons, lambdas, and $\Xi$ baryons in $p$-Pb and $p$-$p$ scattering, compared to experimental data and many other models. In this way we show in a quantitative fashion that $p$-Pb data (and even $p$-$p$ ones) show the typical “flow effect” of enhanced particle production at intermediate $p_t$ values, more and more visible with increasing hadron mass.