Nuclear Theory·nucl-th

Thursday·February 9, 2017

7 papers—6 primary·1 cross-listed

01
[Submitted on 7 Feb 2017]
Alpha particle clusters and their condensation in nuclear systems
Peter Schuck · Yasuro Funaki · Hisashi Horiuchi · Gerd Roepke · Akihiro Tohsaki · Taiichi Yamada
In this article we review the present status of alpha clustering in nuclear systems. First of all, an important aspect is condensation in nuclear matter. Second, the alpha container model, recently been proposed by Tohsaki-Horiuchi-Schuck-Roepke (THSR), will be outlined and the ensuing condensate aspect of the Hoyle state at 7.65 MeV in 12C will be investigated in some detail. After 15 years since the proposal of the alpha condensation concept a critical assessment of this idea will be given. Alpha gas states in other nuclei like 16O and 13C will be considered. The THSR wave function can also describe configurations of one alpha particle on top of a doubly magic core. The cases of 20Ne and 212Po will be investigated.
Comments:
review article
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1702.02191 [pdf]
Phys.Scripta(2016)·65 citations
02
[Submitted on 8 Feb 2017]
$Δ$ isobars in hyperon stars in a modified quark meson coupling model
H.S. Sahoo🇮🇳 · R.N. Mishra🇮🇳 · P.K. Panda🇮🇳 · N. Barik🇮🇳
The possibility of the appearance of $Δ$ isobars in neutron star matter and the so called {\it $Δ$ puzzle} is studied in a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $σ$ , $ω$ , and $ρ$ mesons through mean-field approximations. The couplings of the $Δ$ to the meson fields are fixed from available constraints while the hyperon couplings are fixed from the optical potential values. It is observed that within the constraints of the mass of the precisely measured massive pulsars, PSR J0348+0432 and PSR J1614-2230, neutron stars with a composition of both $Δ$ isobars and hyperons is possible. It is also observed that with an increase in the vector coupling strength of the $Δ$ isobars there is a decrease in the radius of the neutron stars.
Comments:
8 pages, submitted forpublication. arXiv admin note: substantial text overlap with arXiv:1609.02708
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1702.02310 [pdf]
3 citations
03
[Submitted on 8 Feb 2017]
Anisotropic flow of thermal photons at RHIC and LHC
Rupa Chatterjee🇮🇳 · Pingal Dasgupta🇮🇳 · Dinesh K. Srivastava🇮🇳
We calculate elliptic and triangular flow parameters of thermal photons using an event-by-event hydrodynamic model with fluctuating initial conditions at 200A GeV Au+Au collisions at RHIC and at 2.76A TeV Pb+Pb collisions at the LHC for three different centrality bins. The photon elliptic flow shows strong centrality dependence where $v_{2} (p_{T})$ increases towards peripheral collisions both at RHIC and at the LHC energies. However, the triangular flow parameter does not show significant dependence to the collision centrality. The elliptic as well as the triangular flow parameters found to underestimate the PHENIX data at RHIC by a large margin for all three centrality bins. We calculate $p_{T}$ spectrum and anisotropic flow of thermal photons from 200A GeV Cu+Cu collisions at RHIC for 0--20\% centrality bin and compare with the results with those from Au+Au collisions. The production of thermal photon is found to decrease significantly for Cu+Cu collisions compared to Au+Au collisions. However, the effect of initial state fluctuation is found to be more pronounced for anisotropic flow resulting in larger $v_{2}$ and $v_{3}$ for Cu+Cu collisions. We study the correlation between the anisotropic flow parameters and the corresponding initial spatial anisotropies from their event by event distributions at RHIC and at the LHC energies. The linear correlation between $v_{2}$ and $ϵ_{2}$ is found be stronger compared to the correlation between $v_{3}$ and $ϵ_{3}$ . In addition, the correlation coefficient is found to be larger at LHC than at RHIC.
Comments:
9 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1702.02378 [pdf]
PRC(2017)·33 citations
04
[Submitted on 8 Feb 2017]
Mirror Nuclei of 17O and 17F in Relativistic and Non- Relativistic Shell Model
M. Mousavi · M. R. Shojaei
We have investigated energy levels mirror nuclei of the 17O and 17F in relativistic and non-relativistic shell model. The nuclei 17O and 17F can be modeled as a doubly-magic 17O=n+(N=Z=8) and 17F=p+(N=Z=8), with one additional nucleon (valence) in the ld5/2 level. Then we have selected the quadratic Hellmann potential for interaction between core and single nucleon. Using Parametric Nikiforov-Uvarov method, we have calculated the energy levels and wave function in Dirac and Schrodinger equations for relativistic and non-relativistic, respectively. Finally, we have computed the binding and excited energy levels for mirror nuclei of 17O and 17F and compare with other works. Our results were in agreement with experimental values and hence this model could be applied for similar nuclei.
Comments:
6 pages, 2 tables, no figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1702.02417 [pdf]
Adv.High Energy Phys.(2017)·7 citations
05
[Submitted on 8 Feb 2017]
Nuclear matrix element of neutrinoless double- $β$ decay: Relativity and short-range correlations
L. S. Song🇨🇳 · J. M. Yao🇺🇸 · P. Ring🇨🇳 · J. Meng🇨🇳
Background: The discovery of neutrinoless double-beta ( $0 ν β β$ ) decay would demonstrate the nature of neutrinos, have profound implications for our understanding of matter-antimatter mystery, and solve the mass hierarchy problem of neutrinos. The calculations for the nuclear matrix elements $M^{0 ν}$ of $0 ν β β$ decay are crucial for the interpretation of this process. Purpose: We study the effects of relativity and nucleon-nucleon short-range correlations on the nuclear matrix elements $M^{0 ν}$ by assuming the mechanism of exchanging light or heavy neutrinos for the $0 ν β β$ decay. Methods: The nuclear matrix elements $M^{0 ν}$ are calculated within the framework of covariant density functional theory, where the beyond-mean-field correlations are included in the nuclear wave functions by configuration mixing of both angular-momentum and particle-number projected quadrupole deformed mean-field states. Results: The nuclear matrix elements $M^{0 ν}$ are obtained for ten $0 ν β β$ -decay candidate nuclei. The impact of relativity is illustrated by adopting relativistic or nonrelativistic decay operators. The effects of short-range correlations are evaluated. Conclusions: The effects of relativity and short-range correlations play an important role in the mechanism of exchanging heavy neutrinos though the influences are marginal for light neutrinos. Combining the nuclear matrix elements $M^{0 ν}$ with the observed lower limits on the $0 ν β β$ -decay half-lives, the predicted strongest limits on the effective masses are $∣ ⟨ m_{ν} ⟩ ∣ < 0.06 eV$ for light neutrinos and $∣ ⟨ m_{ν_{h}}^{- 1} ⟩ ∣^{- 1} > 3.065 \times 1 0^{8} GeV$ for heavy neutrinos.
Comments:
24 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1702.02448 [pdf]
PRC(2017)·118 citations
06
[Submitted on 8 Feb 2017]
Nuclear cluster structure effect on elliptic and triangular flows in heavy-ion collisions
S. Zhang🇨🇳 · Y. G. Ma🇨🇳 · J. H. Chen🇨🇳 · W. B. He🇨🇳 · C. Zhong🇨🇳
The initial geometry effect on collective flows, which are inherited from initial projectile structure, is studied in relativistic heavy-ion collisions of $^{12}$ C + Au by using a multi-phase transport model (AMPT). Elliptic flow ( $v_{2}$ ) and triangular flow ( $v_{3}$ ) which are significantly resulted from the chain and triangle structure of $^{12} C$ with three- $α$ clusters, respectively, in central $^{12} C$ + $^{197} Au$ collisions are compared with the flow from the Woods-Saxon distribution of nucleons in $^{12} C$ . $v_{3} / v_{2}$ is proposed as a probe to distinguish the pattern of $α$ -clustered $^{12} C$ . This study demonstrates that the initial geometry of the collision zone inherited from nuclear structure can be explored by collective flow at the final stage in heavy-ion collisions.
Comments:
7 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1702.02507 [pdf]
PRC(2017)·69 citations

Affiliations

first authorsco-authorsvia INSPIRE

Alpha particle clusters and their condensation in nuclear systems

Δ isobars in hyperon stars in a modified quark meson coupling model

Anisotropic flow of thermal photons at RHIC and LHC

Mirror Nuclei of 17O and 17F in Relativistic and Non- Relativistic Shell Model

Nuclear matrix element of neutrinoless double-β decay: Relativity and short-range correlations

Nuclear cluster structure effect on elliptic and triangular flows in heavy-ion collisions

Affiliations

$Δ$ isobars in hyperon stars in a modified quark meson coupling model

Nuclear matrix element of neutrinoless double- $β$ decay: Relativity and short-range correlations