Nuclear Theory·nucl-th

Thursday·April 13, 2017

15 papers—9 primary·6 cross-listed

01
Toward the description of fluid dynamical fluctuations in heavy-ion collisions
Marlene Nahrgang🇫🇷 · Marcus Bluhm🇵🇱 · Thomas Schäfer🇺🇸 · Steffen Bass🇺🇸
In this talk we present results obtained when fluid dynamical fluctuations are included in relativistic $3 + 1$ dimensional viscous fluid dynamics. We discuss effects of the interactions of fluctuations due to nonlinearities and the cutoff dependence.
nucl-thActa Phys.Polon.Supp.(2017)·23 citations
02
Local and global $Λ$ polarization in a vortical fluid
Hui Li🇨🇳 · Hannah Petersen🇩🇪 · Long-Gang Pang🇺🇸 · Qun Wang🇨🇳 · Xiao-Liang Xia🇨🇳 · Xin-Nian Wang🇨🇳
We compute the fermion spin distribution in the vortical fluid created in off-central high-energy heavy-ion collisions. We employ the event-by-event (3+1)D viscous hydrodynamic model. The spin polarization density is proportional to the local fluid vorticity in quantum kinetic theory. As a result of strong collectivity, the spatial distribution of the local vorticity on the freeze-out hyper-surface strongly correlates to the rapidity and azimuthal angle distribution of fermion spins. We investigate the sensitivity of the local polarization to the initial fluid velocity in the hydrodynamic model and compute the global polarization of {\Lambda} hyperons by the AMPT model. The energy dependence of the global polarization agrees with the STAR data.
nucl-thhep-exhep-phNPA(2017)·19 citations
03
Two-photon exchange corrections to $γ^{*} N Δ$ form factors for $Q^{2} \leq 4$ (Gev/ $c$ ) $^{2}$
Hai-Qing Zhou🇨🇳 · Shin Nan Yang🇹🇼
We evaluate the corrections of the two-photon exchange (TPE) process on the $γ^{*} N Δ$ transition form factors. The contributions of the TPE process to the $e N \to e Δ (1232) \to e N π$ are calculated in a hadronic model with the inclusion of only the elastic nucleon intermediate states, to estimate its effects on the multipoles $M_{1^{+}}^{(3/2)}, E_{1^{+}}^{(3/2)}, S_{1^{+}}^{(3/2)}$ at the $Δ$ peak. We find that TPE effects on $G_{M}^{*}$ is very small. $G_{E}^{*},$ and $G_{C}^{*}$ are also little affected at small $Q^{2}$ . For $G_{E}^{*}$ , the TPE effects reach about $3 - 8%$ near $Q^{2} \sim 4$ GeV $^{2}$ , depending on the model, MAID or SAID, used to emulate the data. For $G_{C}^{*}$ , the TPE effects decrease rapidly with increasing $ϵ$ while growing with increasing $Q^{2}$ to reach $\sim 6 - 15%$ with $Q^{2} \sim 4$ GeV $^{2}$ at $ϵ = 0.2$ . Sizeable TPE corrections to $G_{E}^{*}$ and $G_{C}^{*}$ found here points to the need of including TPE effects in the multipole analysis in the region of high $Q^{2}$ and small $ϵ$ . The TPE corrections to $R_{E M}$ and $R_{S M}$ obtained in our hadronic calculation are compared with those obtained in a partonic calculation for moderate momentum transfer of $2 < Q^{2} < 4$ GeV $^{2}$ .
nucl-thhep-phnucl-exPRC(2017)·13 citations
04
Examination of $N^{*} (1535)$ as a probe to observe the partial restoration of chiral symmetry in nuclear matter
Daiki Suenaga🇯🇵
We investigate modifications of mass and decay width of $N^{*} (1535)$ in nuclear matter in a chiral symmetric way. The nucleon and $N^{*} (1535)$ are introduced by a parity doublet model, and nuclear matter is constructed by one-loop diagrams of the nucleon and $N^{*} (1535)$ . The decay width of $N^{*} (1535)$ is studied respecting chiral symmetry. Our calculations show that the partial width of $Γ_{N^{*} \to N π}$ is slightly broadened by a collisional broadening, and that of $Γ_{N^{*} \to N η}$ is drastically suppressed at density. As a result, the total decay width $Γ_{tot}$ gets small at density. These modifications, especially the drastic narrowing of partial width of $Γ_{N^{*} \to N η}$ , together with the dropping of mass of $N^{*} (1535)$ provide experiments for observing the partial restoration of chiral symmetry in nuclear matter by means of $N^{*} (1535)$ resonance with useful information.
nucl-thhep-phPRC(2018)·32 citations
05
Effects of jet-induced medium excitation in $γ$ -hadron correlation in A+A collisions
Wei Chen🇨🇳 · Shanshan Cao🇺🇸 · Tan Luo🇨🇳 · Long-Gang Pang🇺🇸 · Xin-Nian Wang🇨🇳
Coupled Linear Boltzmann Transport and hydrodynamics (CoLBT-hydro) is developed for co-current and event-by-event simulations of jet transport and jet-induced medium excitation (j.i.m.e.) in high-energy heavy-ion collisions. This is made possible by a GPU parallelized (3+1)D hydrodynamics that has a source term from the energy-momentum deposition by propagating jet shower partons and provides real time update of the bulk medium evolution for subsequent jet transport. Hadron spectra in $γ$ -jet events of A+A collisions at RHIC and LHC are calculated for the first time that include hadrons from both the modified jet and j.i.m.e.. CoLBT-hydro describes well experimental data at RHIC on the suppression of leading hadrons due to parton energy loss. It also predicts the enhancement of soft hadrons from j.i.m.e. The onset of soft hadron enhancement occurs at a constant transverse momentum due to the thermal nature of soft hadrons from j.i.m.e. which also have a significantly broadened azimuthal distribution relative to the jet direction. Soft hadrons in the $γ$ direction are, on the other hand, depleted due to a diffusion wake behind the jet.
nucl-thhep-phPLB(2018)·182 citations
06
Low- $x$ Physics in $p A$ Collisions and at the EIC
Bo-Wen Xiao🇨🇳
In this proceeding, I review what we have learned, and what we will be able to learn, about low- $x$ physics from proton-nucleus ( $p A$ ) collisions at RHIC and the LHC, and how this complements future Electron-Ion Collider (EIC) measurements. EIC not only will provide us essential and complementary information about the gluon saturation to the knowledge that we have learned from $p A$ collisions at RHIC and the LHC, it will also allow us to visualize the internal structure of protons and nuclei in a multi-dimensional fashion with unprecedented precision.
nucl-thhep-phnucl-exNPA(2017)·3 citations
07
Continuum effects in neutron-drip-line oxygen isotopes
K. Fossez · J. Rotureau · N. Michel · W. Nazarewicz
The binding-energy pattern along the neutron-rich oxygen chain, governed by an interplay between shell effects and many-body correlations impacted by strong couplings to one- and two-neutron continuum, make these isotopes a unique testing ground for nuclear models. In this work, we investigate ground states and low-lying excited states of $^{23 - 28}$ O using the complex-energy Gamow Shell Model and Density Matrix Renormalization Group method with a finite-range two-body interaction optimized to the bound states and resonances of $^{23 - 26}$ O, assuming a core of $^{22}$ O. Our results suggest that the ground-state of $^{28}$ O has a threshold character, i.e., is very weakly bound or slightly unbound. We also predict narrow excited resonances in $^{25}$ O and $^{27}$ O. The inclusion of the large continuum space significantly impacts predicted binding energies of $^{26 - 28}$ O. This implies that the careful treatment of neutron continuum is necessary prior to assessing the spectroscopic quality of effective interactions in this region.
nucl-thPRC(2017)·48 citations
08
Semiclassical approximation to the Hartree-Fock method in finite nuclei
K. A. Gridnev · V. B. Soubbotin · X. Viñas · M. Centelles
In this paper we review the semiclassical extended Thomas-Fermi theory for describing the ground-state properties of nuclei. The binding energies calculated in this approach do not contain shell effects and, in this sense, they are analogous to those obtained from the mass formula. We discuss some techniques for incorporating the shell effects which are missing in the semiclassical calculation, such as the so-called expectation value method and the Kohn-Sham scheme. We present numerical applications for effective zero-range Skyrme forces and finite-range Gogny forces.
nucl-th4 citations
09
Deformation properties with a finite range simple effective interaction
B. Behera · X. Viñas · T. R. Routray · L. M. Robledo · M. Centelles · S. P. Pattnaik
Deformed and spherical even-even nuclei are studied using a finite range simple effective interaction within the Hartree-Fock-Bogoliubov mean field approach. Different parameter sets of the interaction, corresponding to different incompressibility, are constructed by varying the exponent gamma of the density in the traditional density-dependent term. Ten of the twelve parameters of these interactions are determined from properties of asymmetric nuclear matter and spin polarized pure neutron matter. The two remaining parameters are fitted to reproduce the experimental binding energies known in 620 even-even nuclei using several variants of the rotational energy correction. The rms deviations for the binding energy depend on the value of gamma and the way the rotational energy correction is treated but they can be as low as 1.56 MeV, a value competitive with other renowned effective interactions of Skyrme and Gogny type. Charge radii are compared to the experimental values of 313 even-even nuclei and the rms deviation is again comparable and even superior to the one of popular Skyrme and Gogny forces. Emphasis is given to the deformation properties predicted with these interactions by analyzing the Potential Energy Surfaces for several well deformed nuclei and the fission barriers of some nuclei. Comparison of the results with the experimental information, where available, as well as with the results of the Gogny D1S force shows satisfactory agreement.
nucl-thJ.Phys.G(2016)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE