Nuclear Theory·nucl-th

Monday·May 15, 2017

7 papers—4 primary·3 cross-listed

01
Variational calculation of the ground state of closed-shell nuclei up to $A = 40$
D. Lonardoni · A. Lovato · Steven C. Pieper · R. B. Wiringa
Variational calculations of ground-state properties of $^{4}$ He, $^{16}$ O, and $^{40}$ Ca are carried out employing realistic phenomenological two- and three-nucleon potentials. The trial wave function includes two- and three-body correlations acting on a product of single-particle determinants. Expectation values are evaluated with a cluster expansion for the spin-isospin dependent correlations considering up to five-body cluster terms. The optimal wave function is obtained by minimizing the energy expectation value over a set of up to 20 parameters by means of a nonlinear optimization library. We present results for the binding energy, charge radius, one- and two-body densities, single-nucleon momentum distribution, charge form factor, and Coulomb sum rule. We find that the employed three-nucleon interaction becomes repulsive for $A \geq 16$ . In $^{16}$ O the inclusion of such a force provides a better description of the properties of the nucleus. In $^{40}$ Ca instead, the repulsive behavior of the three-body interaction fails to reproduce experimental data for the charge radius and the charge form factor. We find that the high-momentum region of the momentum distributions, determined by the short-range terms of nuclear correlations, exhibit a universal behavior independent of the particular nucleus. The comparison of the Coulomb sum rules for $^{4}$ He, $^{16}$ O, and $^{40}$ Ca reported in this work will help elucidate in-medium modifications of the nucleon form factors.
nucl-thnucl-exPRC(2017)·86 citations
02
Conserved charge fluctuations using the $D$ -measure in heavy-ion collisions
D. K. Mishra🇮🇳 · P. K. Netrakanti🇮🇳 · P. Garg🇺🇸
We study the net-charge fluctuations, $D$ -measure variable, in high energy heavy-ion collisions in heavy-ion jet interaction generator (HIJING), ultrarelativistic quantum molecular dynamics (UrQMD) and hadron resonance gas (HRG) models for various center-of-mass energies (\sqsn). The effect of kinematic acceptance and resonance decay, in the pseudorapidity acceptance interval ( $Δ η$ ) and lower transverse momentum ( $p_{T}^{min}$ ) threshold, on fluctuation measures are discussed. A strong dependence of $D$ with the $Δ η$ in HIJING and UrQMD models is observed as opposed to results obtained from the HRG model. The dissipation of fluctuation signal is estimated by fitting the $D$ -measure as a function of the $Δ η$ . An extrapolated function for higher $Δ η$ values at lower \sqsn is different from the results obtained from models. Particle species dependence of $D$ and the effect of the $p_{T}^{min}$ selection threshold are discussed in HIJING and HRG models. The comparison of $D$ , at midrapidity, of net-charge fluctuations at various \sqsn obtained from the models with the data from the ALICE experiment is discussed. The results from the present work as a function of $Δ η$ and \sqsn will provide a baseline for comparison to experimental measurements.
nucl-thhep-phnucl-exPRC(2017)·6 citations
03
Exact Solutions to the Fermion Propagator Schwinger-Dyson Equation in Minkowski space with on-shell Renormalization for Quenched QED
Shaoyang Jia🇺🇸 · M.R. Pennington🇺🇸
With the introduction of a spectral representation, the Schwinger-Dyson equation (SDE) for the fermion propagator is formulated in Minkowski space in QED. After imposing the on-shell renormalization conditions, analytic solutions for the fermion propagator spectral functions are obtained in four dimensions with a renormalizable version of the Gauge Technique anzatz for the fermion-photon vertex in the quenched approximation in the Landau gauge. Despite the limitations of this model, having an explicit solution provides a guiding example of the fermion propagator with the correct analytic structure. The Padé approximation for the spectral functions is also investigated.
nucl-thhep-phhep-thPRD(2017)·23 citations
04
Strong Diffusion Effect of Charm Quarks on $J / ψ$ Production in Pb-Pb collisions at the LHC
Jiaxing Zhao🇨🇳 · Baoyi Chen
We study the $J / ψ$ production based on coalescence model at $s_{N N}$ = 2.76 and 5.02 TeV Pb-Pb collisions. With the colliding energy increasing from 2.76 TeV to 5.02 TeV, the number of charm pairs is enhanced by more than 50%. However, the ratio of $J / ψ$ inclusive nuclear modification factors $R_{AA}^{5.02 T e V} / R_{AA}^{2.76 T e V}$ is only about 1.1 $\sim$ 1.2. We find that the regeneration of $J / ψ$ is proportional to the densities of charm and anti-charm quarks, instead of their total numbers. The charm quark density is diluted by the strong expansion of quark gluon plasma, which suppresses the combination probability of heavy quarks and $J / ψ$ regeneration. This effect is more important in higher colliding energies where QGP expansion is strong. We also propose the ratio $N_{J / ψ} / (N_{D})^{2}$ as a measurement of $c$ and $c ˉ$ coalescence probability, which is only affected by the heavy quark diffusions in QGP, and does not depend on the inputs such as cold nuclear matter effects and cross sections of charm quark production. Further more, we give the predictions at the energy of Future Circular Collider ( $s_{N N}$ = 39 TeV).
nucl-thPLB(2018)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE

Variational calculation of the ground state of closed-shell nuclei up to A=40

Conserved charge fluctuations using the D-measure in heavy-ion collisions

Exact Solutions to the Fermion Propagator Schwinger-Dyson Equation in Minkowski space with on-shell Renormalization for Quenched QED

Strong Diffusion Effect of Charm Quarks on J/ψ Production in Pb-Pb collisions at the LHC

Affiliations

Variational calculation of the ground state of closed-shell nuclei up to $A = 40$

Conserved charge fluctuations using the $D$ -measure in heavy-ion collisions

Strong Diffusion Effect of Charm Quarks on $J / ψ$ Production in Pb-Pb collisions at the LHC