Nuclear Theory·nucl-th

Friday·June 3, 2016

14 papers—8 primary·6 cross-listed

01
[Submitted on 1 Jun 2016]
Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions: I. Theoretical Framework
Oswaldo Artiles · Misak M. Sargsian
We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energies based on the multi-nucleon short-range correlation~(SRC) model. The approach is based on the effective Feynman diagrammatic method which allows to account for the relativistic effects important in the SRC domain. In addition to two-nucleon SRC with center of mass motion we derive also the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short range NN interactions. This approach allowed us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contributions to the spectral function. The derivations of the spectral functions are based on the two theoretical frameworks in evaluating covariant Feynman diagrams: In the first, referred as virtual nucleon approximation, we reduce Feynman diagrams to the time ordered noncovariant diagrams by evaluating nucleon spectators in the SRC at their positive energy poles, neglecting explicitly the contribution from vacuum diagrams. In the second approach, referred as light-front approximation, we formulate the boost invariant nuclear spectral function in the light-front reference frame in which case the vacuum diagrams are generally suppressed and the bound nucleon is described by its light-cone variables such as momentum fraction, transverse momentum and invariant mass.
Comments:
34 pages and 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1606.00468 [pdf]
PRC(2016)·21 citations
02
[Submitted on 2 Jun 2016]
Study for (anti)hypertriton and light (anti)nuclei productions in high energy collisions at 200 GeV
Hai-Jun Li🇨🇳 · Ting-Ting Zeng🇨🇳 · Gang Chen🇨🇳
We use the parton and hadron cascade (PACIAE) model and the dynamically constrained phase-space coalescence (DCPC) model to investigate the productions of (anti)hypertriton and light (anti)nuclei generated by 0-10% centrality $^{12}$ C+ $^{12}$ C, $^{24}$ Mg+ $^{24}$ Mg, $^{40}$ Ca+ $^{40}$ Ca, and $^{64}$ Cu+ $^{64}$ Cu collisions at $S_{N N}$ = 200 GeV with $∣ y ∣$ $<$ 1.5 and $p_{T}$ $<$ 5. We study the yield ratios of the antiparticle to particle and the rapidity distributions of the different (anti)nuclei. We find that the amounts of antimatter produced are significantly lower than that of the corresponding particles, the results of theoretical models are well consistent with the PHOBOS data. The yield ratios of the particle to antiparticle in different transverse momentum regions are also given, and we find that the ratios are raise with the increase of the transverse momentum.
Comments:
6pages, 3figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.00537 [pdf]
2 citations
03
[Submitted on 2 Jun 2016]
Particle-number conserving analysis of the high-spin structure of $^{159}$ Ho
Zhen-Hua Zhang
The high-spin rotational bands in odd- $Z$ nuclei $^{159}$ Ho ( $Z = 67$ ) are investigated using the cranked shell model with the pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $ℏ ω$ are reproduced very well by the calculations. The splitting between the signature partners of the yrast band $7/ 2^{-} [523]$ is discussed and the splitting of the excited band $7/ 2^{+} [404]$ above $ℏ ω \sim 0.30$ ~MeV is predicted due to the level crossing with $1/ 2^{+} [411]$ . The calculated $B (E 2)$ transition probabilities are also suggested for future experiments.
Comments:
20 pages, 7 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1606.00570 [pdf]
NPA(2016)·12 citations
04
[Submitted on 2 Jun 2016]
Investigation of the two-quasiparticle bands in the doubly-odd nucleus $^{166}$ Ta using a particle-number conserving cranked shell model
Zhen-Hua Zhang
The high-spin rotational properties of two-quasiparticle bands in the doubly-odd $^{166}$ Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $ℏ ω$ are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.
Comments:
7 pages, 5 figures. arXiv admin note: text overlap with arXiv:1606.00570
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1606.00573 [pdf]
SCPMA(2016)·7 citations
05
[Submitted on 2 Jun 2016]
Precise Determination of Charge Dependent Pion-Nucleon-Nucleon Coupling Constants
R. Navarro Perez🇺🇸 · J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸
We undertake a covariance error analysis of the pion-nucleon-nucleon coupling constants from the Granada-2013 np and pp database comprising a total of 6720 scattering data below LAB energy of 350 MeV. Assuming a unique pion-nucleon coupling constant in the One Pion Exchange potential above a boundary radius $r_{c} = 3 fm$ we obtain $f^{2} = 0.0763 (1)$ . The effects of charge symmetry breaking on the $^{3} P_{0}$ , $^{3} P_{1}$ and $^{3} P_{2}$ partial waves are analyzed and we find $f_{p}^{2} = 0.0761 (4)$ , $f_{0}^{2} = 0.0790 (9)$ and $f_{c}^{2} = 0.0772 (6)$ with a strong anti-correlation between $f_{c}^{2}$ and $f_{0}^{2}$ . We successfully test normality for the residuals of the fit. Potential tails in terms of different boundary radii as well as chiral Two-Pion-Exchange contributions as sources of systematic uncertainty are also investigated.
Comments:
14 pages, 6 figures, 13 tables. Discussion on naturalness, Analysis of systematic errors, Inclusion of Two Pion Exchange and Tables with phases-shifts added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1606.00592 [pdf]
PRC(2017)·46 citations
06
[Submitted on 2 Jun 2016]
QCD sum rules for the neutron, $Σ$ , and $Λ$ in neutron matter
Kie Sang Jeong🇰🇷 · Giju Gye🇰🇷 · Su Houng Lee🇰🇷
The nuclear density dependencies of the neutron and $Σ$ and $Λ$ hyperons are important inputs in the determination of the neutron star mass as the appearance of hyperons coming from strong attractions significantly changes the stiffness of the equation of state (EOS) at iso-spin asymmetric dense nuclear matter. In-medium spectral sum rules have been analyzed for the nucleon, $Σ$ , and $Λ$ hyperon to investigate their properties up to slightly above the saturation nuclear matter density by using the linear density approximation for the condensates. The construction scheme of the interpolating fields without derivatives has been reviewed and used to construct a general interpolating field for each baryon with parameters specifying the strength of independent interpolating fields. Optimal choices for the interpolating fields were obtained by requiring the sum rules to be stable against variations of the parameters and the result to be consistent with known phenomenology. The optimized result shows that Ioffe's choice is not suitable for the $Λ$ hyperon sum rules. It is found that, for the $Λ$ hyperon interpolating field, the up and down quark combined into the scalar diquark structure $u^{T} C γ_{5} d$ should be emphasized to ensure stable sum rules. The quasi- $Σ$ and - $Λ$ hyperon energies are always found to be higher than the quasineutron energy in the region $0.5 < ρ / ρ_{0} < 1.5$ where the linear density approximation in the sum-rule analysis is expected to be reliable.
Comments:
19 pages, 10 figures (4 diagrams, 25 graphs). Typos are corrected and content is rearranged as appearing form in the published article (The contents overlapped with the previously reported works by other authors have been omitted)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1606.00594 [pdf]
PRC(2016)·9 citations
07
[Submitted on 2 Jun 2016]
Fusion and quasifission dynamics in the reactions $^{48}$ Ca+ $^{249}$ Bk and $^{50}$ Ti+ $^{249}$ Bk using TDHF
A.S. Umar · V.E. Oberacker · C. Simenel
Background: Synthesis of superheavy elements (SHE) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure of the reactants. New SHE have been recently produced with doubly-magic $^{48}$ Ca beams. However, SHE synthesis experiments with single-magic $^{50}$ Ti beams have so far been unsuccessful. Purpose: In connection with experimental searches for $Z = 117, 119$ superheavy elements, we perform a theoretical study of fusion and quasifission mechanisms in $^{48}$ Ca, $^{50}$ Ti+ $^{249}$ Bk reactions in order to investigate possible differences in reaction mechanisms induced by these two projectiles. Methods: The collision dynamics and the outcome of the reactions are studied using unrestricted time-dependent Hartree-Fock (TDHF) calculations as well as the density-constrained TDHF method to extract the nucleus-nucleus potentials and the excitation energy in each fragment. Results: Nucleus-nucleus potentials, nuclear contact times, masses and charges of the fragments, as well as their kinetic and excitation energies strongly depend on the orientation of the prolate $^{249}$ Bk nucleus. Long contact times associated with fusion are observed in collisions of both projectiles with the side of the $^{249}$ Bk nucleus, but not on collisions with its tip. The energy and impact parameter dependences of the fragment properties, as well as their mass-angle and mass-total kinetic energy correlations are investigated. Conclusions: Entrance channel reaction dynamics are similar with both $^{48}$ Ca and $^{50}$ Ti projectiles. Both are expected to lead to the formation of a compound nucleus by fusion if they have enough energy to get in contact with the side of the $^{249}$ Bk target.
Comments:
15 figures, 13 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.00699 [pdf]
PRC(2016)·99 citations
08
[Submitted on 2 Jun 2016]
Phenomenological Consequences of Enhanced Bulk Viscosity Near the QCD Critical Point
Akihiko Monnai🇫🇷 · Swagato Mukherjee🇺🇸 · Yi Yin🇺🇸
In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. This work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding $1 + 1$ dimensional causal relativistic hydrodynamical evolution at non-zero baryon density. We demonstrate that the critically-enhanced bulk viscosity induces a substantial non-equilibrium pressure, effectively softening the equation of state, and leads to sizable effects in the flow velocity and single particle distributions at the freeze-out. The observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complimentary information to facilitate searches for the QCD critical point.
Comments:
8 pages, 5 figures, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1606.00771 [pdf]
PRC(2017)·64 citations

Affiliations

first authorsco-authorsvia INSPIRE