Nuclear Theory·nucl-th

Thursday·June 7, 2018

7 papers—3 primary·4 cross-listed

01
[Submitted on 5 Jun 2018]
The Fullerene-like Structure of Superheavy Element Z=120 (Greinerium)-a tribute to Walter Greiner
S. Misicu · I. N. Mishustin
We review the basic ideas and some theoretical models behind the concept of fullerene-like structures made of $α$ -particles. The possibility of such a peculiar nuclear shape developing in a double magic superheavy nucleus with $Z$ =120 was mentioned for the first time in the literature by Walter Greiner and then constantly defended by him. We provide estimates of the energy of such metastable states within the liquid-drop model. In the second part of this paper we discuss a simple model rooted in the nontopological soliton model consisting of a complex scalar field describing a finite system of $α$ bosons with non-linear self-interactions coupled to the electromagnetic field. We demonstrate that this model predicts density depletion in the central region of a soliton-like structure for a range of model parameters.
Comments:
12 pages, 6 figures, Walter Greiner Memorial Volume, p.263-274 Edited by: Peter O. Hess and Horst Stöcker, World Scientific, Singapore 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.01886 [pdf]
2 citations
02
[Submitted on 6 Jun 2018]
Fate of the neutron-deuteron virtual state as an Efimov level
Gautam Rupak🇺🇸 · Akshay Vaghani🇺🇸 · Renato Higa🇧🇷 · Ubirajara van Kolck🇫🇷
The emergence of Efimov levels in a three-body system is investigated near the unitarity limit characterized by resonating two-body interaction. No direct evidence of Efimov levels is seen in the three-nucleon system since the triton is the only physical bound state. We provide a model-independent analysis of nucleon-deuteron scattering at low energy by formulating a consistent effective field theory. We show that virtual states evolve into shallow bound states, which emerge as excited triton levels as we drive the system towards unitarity. Even though we consider this specific system, our results for the emergence of the Efimov levels are universal.
Comments:
7 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.01999 [pdf]
PLB(2019)·29 citations
03
[Submitted on 6 Jun 2018]
Spurious finite-size instabilities with Gogny-type interactions
M. Martini🇫🇷 · A. De Pace🇮🇹 · K. Bennaceur🇫🇷
Recently, a new parameterization of the Gogny interaction suitable for astrophysical applications, named D1M*, has been presented. We investigate the possible existence of spurious finite-size instabilities of this new Gogny force by repeating a study that we have already performed for the most commonly used parameterizations (D1, D1S, D1N, D1M) of the Gogny force. This study is based on a fully-antisymmetrized random phase approximation (RPA) calculation of the nuclear matter response functions employing the continued fraction technique. It turns out that this new Gogny interaction is affected by spurious finite-size instabilities in the scalar isovector channel; hence, unphysical results are expected in the calculation of properties of nuclei, like neutron and proton densities, if this D1M* force is used. The conclusions from this study are then, for the first time, tested against mean-field calculations in a coordinate representation for several nuclei. Unphysical results for several nuclei are also obtained with the D1N parameterization of the Gogny force. These observations strongly advocate for the use of the linear response formalism to detect and avoid finite-size instabilities during the fit of the parameters of Gogny interactions as it is already done for some Skyrme forces.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.02080 [pdf]
EPJA(2019)·14 citations
04
[Submitted on 4 Jun 2018] (cross-list from hep-ph)
Momentum Sum Rule Is Violated in The Operator Product Expansion in QCD At The High Energy Colliders
Gouranga C Nayak🇺🇸
To prove the momentum sum rule in the operator product expansion (OPE) in QCD at high energy colliders it is assumed that $< P ∣ T^^{++} (0) ∣ P >= 2 (P^{+})^{2}$ where $∣ P >$ is the momentum eigenstate of the hadron $H$ with momentum $P^{μ}$ and $T^^{++} (0)$ is the $+ +$ component of the gauge invariant color singlet energy-momentum tensor density operator $T^^{μν} (0)$ of all the quarks plus antiquarks plus gluons inside the hadron $H$ . However, in this paper, we show that this relation $< P ∣ T^^{++} (0) ∣ P >= 2 (P^{+})^{2}$ is correct if $T^^{μν} (0)$ is the energy-momentum tensor density operator of the hadron but this relation $< P ∣ T^^{++} (0) ∣ P >= 2 (P^{+})^{2}$ is not correct if $T^^{μν} (0)$ is the gauge invariant color singlet energy-momentum tensor density operator of all the quarks plus antiquarks plus gluons inside the hadron. Hence we find that the momentum sum rule is violated in the operator product expansion (OPE) in QCD at high energy colliders.
Comments:
11 pages latex
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.01220 [pdf]
1 citation
05
[Submitted on 5 Jun 2018] (cross-list from hep-ph)
Heavy Flavor Azimuthal Correlations in Cold Nuclear Matter
R. Vogt🇺🇸
Background: It has been proposed that the azimuthal distributions of heavy flavor quark-antiquark pairs may be modified in the medium of a heavy-ion collision. Purpose: This work tests this proposition through next-to-leading order (NLO) calculations of the azimuthal distribution, $d σ / d ϕ$ , including transverse momentum broadening, employing $< k_{T}^{2} >$ and fragmentation in exclusive $Q Q ˉ$ pair production. While these studies were done for $p + p$ , $p + p ˉ$ and $p +$ Pb collisions, understanding azimuthal angle correlations between heavy quarks in these smaller, colder systems is important for their interpretation in heavy-ion collisions. Methods: First, single inclusive $p_{T}$ distributions calculated with the exclusive HVQMNR code are compared to those calculated in the fixed-order next-to-leading logarithm approach. Next the azimuthal distributions are calculated and sensitivities to $< k_{T}^{2} >$ , $p_{T}$ cut, and rapidity are studied at $s = 7$ TeV. Finally, calculations are compared to $Q Q ˉ$ data in elementary $p + p$ and $p + p ˉ$ collisions at $s = 7$ TeV and 1.96 TeV as well as to the nuclear modification factor $R_{p Pb} (p_{T})$ in $p +$ Pb collisions at $s_{N N} = 5.02$ TeV measured by ALICE. Results: The low $p_{T}$ ( $p_{T} < 10$ GeV) azimuthal distributions are very sensitive to the $k_{T}$ broadening and rather insensitive to the fragmentation function. The NLO contributions can result in an enhancement at $ϕ \sim 0$ absent any other effects. Agreement with the data was found to be good. Conclusions: The NLO calculations, assuming collinear factorization and introducing $k_{T}$ broadening, result in significant modifications of the azimuthal distribution at low $p_{T}$ which must be taken into account in calculations of these distributions in heavy-ion collisions.
Comments:
29 pages, 21 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.01904 [pdf]
PRC(2018)·27 citations
06
[Submitted on 6 Jun 2018] (cross-list from hep-ph)
$K^{0} Λ$ photoproduction off the neutron with nucleon resonances
Sang-Ho Kim🇰🇷 · Hyun-Chul Kim🇰🇷
We investigate kaon photoproduction off the neutron target, i.e., $γ n \to K^{0} Λ$ , focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of $s \approx 1600 - 2200$ MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with $K Λ$ vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonance $N (1685, 1/ 2^{+})$ on both the total and differential cross sections near the threshold energy. In addition, we present the results of the beam asymmetry as a prediction.
Comments:
13 pages. 7 figures. Final version that will appear in Physics Letters B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1806.01992 [pdf]
PLB(2018)·13 citations
07
[Submitted on 6 Jun 2018] (cross-list from hep-ph)
Thermodynamics of a gas of hadrons with attractive and repulsive interaction within S-matrix formalism
Ashutosh Dash🇮🇳 · Subhasis Samanta🇮🇳 · Bedangadas Mohanty🇮🇳
We report the effect of including repulsive interactions on various thermodynamic observables calculated using a S-matrix based Hadron Resonance Gas (HRG) model to already available corresponding results with only attractive interactions [A. Dash, S. Samanta, and B. Mohanty, Phys. Rev. C 97, 055208 (2018)]. The attractive part of the interaction is calculated by parameterizing the two body phase shifts using K-matrix formalism while the repulsive part is included by fitting to the experimental phase shifts which carry the information about the nature of the interaction. We find that the bulk thermodynamic variables for a gas of hadrons such as energy density, pressure, entropy density, speed of sound and specific heat are suppressed by the inclusion of repulsive interactions and are more pronounced for second and higher order correlations and fluctuations, particularly for the observables $χ_{Q}^{2}$ , $χ_{B}^{2} - χ_{B}^{4}$ and $C_{B S}$ in the present model. We find a good agreement between lattice QCD simulations and the present model for $C_{B S}$ . We have also computed two leading order Fourier coefficients of the imaginary part of the first order baryonic susceptibility at imaginary baryon chemical potential within this model and compared them with the corresponding results from lattice. Additionally, assuming that the value of interacting pressure versus temperature for a gas of hadrons calculated in S-matrix formalism is same as that from a van der Waals HRG (VDWHRG) model, we have quantified the attractive and repulsive interactions in our model in terms of attractive and repulsive parameters used in the VDWHRG model. The values of parameters thus obtained are $a = 1.54 \pm 0.064$ GeV $fm^{3}$ and $r = 0.81 \pm 0.014$ fm.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.02117 [pdf]
PRC(2019)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE

The Fullerene-like Structure of Superheavy Element Z=120 (Greinerium)-a tribute to Walter Greiner

Fate of the neutron-deuteron virtual state as an Efimov level

Spurious finite-size instabilities with Gogny-type interactions

Momentum Sum Rule Is Violated in The Operator Product Expansion in QCD At The High Energy Colliders

Heavy Flavor Azimuthal Correlations in Cold Nuclear Matter

K0Λ photoproduction off the neutron with nucleon resonances

Thermodynamics of a gas of hadrons with attractive and repulsive interaction within S-matrix formalism

Affiliations

$K^{0} Λ$ photoproduction off the neutron with nucleon resonances