Nuclear Theory·nucl-th

Friday·December 5, 2014

10 papers—5 primary·5 cross-listed

01
Electromagnetic production of $K Σ$ on the nucleon near threshold
T. Mart🇮🇩
Photo- and electroproduction of $K Σ$ have been investigated near their production thresholds by using an effective Lagrangian approach. For this purpose, the background amplitude is constructed from suitable Feynman diagrams, whereas the resonance terms are calculated by means of the Breit-Wigner form of multipoles. Experimental data available in the proton channels ( $K^{+} Σ^{0}$ and $K^{0} Σ^{+}$ ) with energies up to 50 MeV above the thresholds have been utilized to extract the unknown parameters. In these proton channels the calculated observables fit nicely the experimental data, whereas in the neutron channels ( $K^{+} Σ^{-}$ and $K^{0} Σ^{0}$ ) the predicted observables contain some uncertainties due to the the uncertainties in the values of helicity photon couplings. To this end, new $K^{0} Σ^{+}$ photoproduction data are urgently required. The present analysis indicates the validity of the $P_{Λ} = - \frac{1}{3} P_{Σ}$ relation derived a long time ago. In the electroproduction sector the present analysis confirms the smooth transition between photoproduction and low $Q^{2}$ electroproduction data. The effect of new Crystal Ball data is shown to be mild at the backward angles. It is also found that the electroproductions of $K^{0} Σ^{+}$ and $K^{0} Σ^{0}$ are practically not the suitable reactions for investigating the $K^{0}$ charge form factor, since the effect is small.
nucl-thhep-phPRC(2014)·27 citations
02
The $η^{'} N$ interaction from a chiral effective model and $η^{'}$ - $N$ bound state
Shuntaro Sakai🇯🇵 · Daisuke Jido🇯🇵
The $η^{'}$ mass reduction in the nuclear medium is expected from the degeneracy of the pseudoscalar-singlet and octet mesons when chiral symmetry is manifest. In this study, we investigate the $η^{'} N$ 2body interaction which is the foundation of the in-medium $η^{'}$ properties using the linear sigma model as a chiral effective model. The $η^{'} N$ interaction in the linear sigma model comes from the scalar meson exchange with U $_{A}$ (1) symmetry effect and is found to be fairly strong attraction. Moreover, the $η N$ transition is included in our calculation, and is important for the imaginary part of the $η^{'}$ -optical potential. The transition amplitude of $η^{'} N$ to the $η N$ channel is relatively small compared to that of elastic channel. From the analysis of the $η^{'} N$ 2body system, we find a $η^{'} N$ bound state with the binding energy $12.3 - 3.3 i$ MeV. We expect that this strongly attractive two body interaction leads to a deep and attractive optical potential.
nucl-thHyperfine Interact.(2015)·8 citations
03
Effects of three-nucleon spin-orbit interaction on isotope shifts of Pb nuclei
H. Nakada · T. Inakura
We investigate effects of the $3 N$ interaction, which effectively adds a density-dependent term to the LS channel, on the isotopes shifts of the Pb nuclei. With the strength so as to keep the $ℓ s$ splitting of the single-nucleon orbits, the density-dependence in the LS channel tends to shrink the wave functions of the $j = ℓ + 1/2$ orbits while makes the $j = ℓ - 1/2$ functions distribute more broadly. Thereby the kink in the isotope shifts of the Pb nuclei at $N = 126$ becomes stronger, owing to the attraction from neutrons occupying $0 i_{11/2}$ in $N > 126$ . The density-dependence in the LS channel enables us to reproduce the data of the isotope shifts by the Hartree-Fock-Bogolyubov calculations in a long chain of neutron numbers, even without degeneracy between the $n 1 g_{9/2}$ and $n 0 i_{11/2}$ levels. We exemplify it by the semi-realistic M3Y-P6 interaction.
nucl-thPRC(2015)·42 citations
04
Directed Flow Indicates a Crossover Deconfinement Transition in Relativistic Nuclear Collisions
Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺
Analysis of directed flow ( $v_{1}$ ) of protons, antiprotons and pions in heavy-ion collisions is performed in the range of incident energies $s_{N N}$ = 2.7--27 GeV. Simulations have been done within a three-fluid model employing a purely hadronic equation of state (EoS) and two versions of the EoS involving deconfinement transitions: a first-order phase transition and a smooth crossover transition. High sensitivity of the directed flow, especially the proton one, to the EoS is found. The crossover EoS is favored by the most part of considered experimental data. A strong wiggle in the excitation function of the proton $v_{1}$ slope at the midrapidity obtained with the first-order-phase-transition EoS and a smooth proton $v_{1}$ with positive midrapidity slope, within the hadronic EoS unambiguously disagree with the data. The pion and antiproton $v_{1}$ also definitely testify in favor of the crossover EoS. The results obtained with deconfinement EoS's apparently indicate that these EoS's in the quark-gluon sector should be stiffer at high baryon densities than those used in the calculation.
nucl-thhep-phnucl-exPRC(2015)·77 citations
05
Time-dependent HF approach to SHE dynamics
A.S. Umar · V.E. Oberacker
We employ the time-dependent Hartree-Fock (TDHF) method to study various aspects of the reactions utilized in searches for superheavy elements. These include capture cross-sections, quasifission, prediction of $P_{CN}$ , and other interesting dynamical quantities. We show that the microscopic TDHF approach provides an important tool to shed some light on the nuclear dynamics leading to the formation of superheavy elements.
nucl-thNPA(2015)·47 citations

Affiliations

first authorsco-authorsvia INSPIRE

Electromagnetic production of KΣ on the nucleon near threshold

The η′N interaction from a chiral effective model and η′-N bound state

Effects of three-nucleon spin-orbit interaction on isotope shifts of Pb nuclei

Directed Flow Indicates a Crossover Deconfinement Transition in Relativistic Nuclear Collisions

Time-dependent HF approach to SHE dynamics

Affiliations

Electromagnetic production of $K Σ$ on the nucleon near threshold

The $η^{'} N$ interaction from a chiral effective model and $η^{'}$ - $N$ bound state