Nuclear Theory·nucl-th

Tuesday·August 8, 2017

13 papers—8 primary·5 cross-listed

01
[Submitted on 6 Aug 2017]
Finite-size effects on the hadron-quark phase transition in neutron stars
Xuhao Wu🇨🇳 · Hong Shen🇨🇳
We study the finite-size effects, like the surface and Coulomb energies, on the hadron-quark mixed phase in neutron stars. The equilibrium conditions for coexisting hadronic and quark phases are derived by minimizing the total energy including the surface and Coulomb contributions, which are different from the Gibbs conditions without finite-size effects. We employ the relativistic mean-field model to describe the hadronic phase, while the Nambu-Jona-Lasinio model with vector interactions is used for the quark phase. It is found that finite-size effects can significantly reduce the region of the mixed phase, and the results lie between those of the Gibbs and Maxwell constructions. We show that a massive star may contain a mixed-phase core and its size depends on the surface tension of the hadron-quark interface and the vector coupling between quarks. The repulsive vector interaction in the Nambu-Jona-Lasinio model can stiffen the equation of state of quark matter, and therefore, delay the phase transition and increase the maximum mass of neutron stars.
Comments:
22 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01878 [pdf]
PRC(2017)·47 citations
02
[Submitted on 6 Aug 2017]
Phase shift formulas for baryon-baryon scattering in elongated boxes
Ning Li🇨🇳 · Ya-Jie Wu🇨🇳 · Zhan-Wei Liu🇨🇳
We have established the relations between the baryon-baryon scattering phase shifts and the two-particle energy spectrum in the elongated box. We have studied the cases with both the periodic boundary condition and twisted boundary condition in the center of mass frame. The framework is also extended to the system of nonzero total momentum with periodic boundary condition in the moving frame. This will be helpful to extract the phase shifts in the continuum from lattice QCD data using asymmetric volumes.
Comments:
13 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01879 [pdf]
0 citations
03
[Submitted on 6 Aug 2017]
{\alpha}-decay half-lives for Pb isotopes within Gamow-like model
Dashty T. Akrawy
We studed alpha decay half-lives of Pb isotopes in the range 178 < A > 220, whithin Gamow-like model (GLM) which is based on Gamow theory. The empirical formulae like Royer formula, Universal Decay Low (UDL), Viola-Seaborg formula (VSS), Semi-empirical formula for Poenaru (SemFIS) and Denisov-Khudenko formula (DEKH) are used to calculate alpha decay half-lives. The results are compared with experimental data, and also with other theoretical models, the results are in a good agreement was achieved with experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01935 [pdf]
0 citations
04
[Submitted on 7 Aug 2017]
The anatomy of atomic nuclei: illuminating many-body wave functions through group-theoretical decomposition
Calvin W. Johnson
With modern computers we can compute nuclear many-body wave functions with an astounding number of component, $> 1 0^{10}$ . But, aside from reproducing and/or predicting experiments, what do we learn from vectors with tens of billions of components? One way to characterize wavefunctions is through irreducible representations of groups. I discuss briefly the history of group-theoretical characterization of nuclear wavefunctions, with an emphasis of using Lanczos-type methods to efficiently dissect arbitrary wavefunctions into group irreps. Although the resulting decompositions are often fragmented over many irreps, one nonetheless finds powerful patterns. First, group decompositions along rotational bands show coherent commonalities, supporting the picture of a shared "intrinsic shape;" this is also called \textit{quasi-dynamical symmetry}. Second, group decompositions for wave functions using both phenomenological and \textit{ab initio} forces are often very similar, despite vastly different origins and dimensionalities. Both of these results suggest a group theoretical decomposition can provide a robust "anatomy" of many nuclear wave functions. This in turn supports the idea of using symmetry-based many-body frameworks for calculations.
Comments:
8 figures, 1 table. To appear in "Emergent Phenomena in Atomic Nuclei from Large-Scale Modeling: A Symmetry-Guided Perspective," K. D. Launey, ed., World Scientific Sept 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01952 [pdf]
0 citations
05
[Submitted on 7 Aug 2017]
Transfer probabilities for the reactions $^{14, 20}$ O+ $^{20}$ O in terms of multiple time-dependent Hartree-Fock-Bogoliubov trajectories
Guillaume Scamps · Yukio Hashimoto
The transfer reaction between two nuclei in the superfluid phase is studied with the Time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. In order to restore the symmetry of the relative gauge angle a set of independent TDHFB evolutions is done. Then the transfer probability is computed using a triple projection method. This method is first tested to determine the transfer probabilities on a toy model and compared to the exact solution. It is then applied to the reactions $^{20}$ O+ $^{20}$ O and $^{14}$ O+ $^{20}$ O in a realistic framework with a Gogny interaction.
Comments:
6 figures, 6 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01994 [pdf]
PRC(2017)·25 citations
06
[Submitted on 7 Aug 2017]
Excitation energy spectra of the Lambda_c and Lambda_b baryons in a finite-size diquark model
Kento Kumakawa🇯🇵 · Daisuke Jido (Tokyo Metropolitan University)🇯🇵
The excitation energies of the $Λ_{c}$ and $Λ_{b}$ baryons are investigated in a finite-size diquark potential model, in which the heavy baryons are treated as bound states of a charm quark and a scalar-isoscalar diquark. The diquark is considered as a sizable object. The quark-diquark interaction is calculated as a sum of the quark-quark interaction which is assumed to be half of the quark-antiquark interaction for the color singlet. The potential parameters in the quark-antiquark interaction are fixed so as to reproduce the charmonium spectrum. We find the diquark size to be 1.1 fm for the diquark mass 0.5 GeV/c $^{2}$ to reproduce the $1 p$ excitation energy of $Λ_{c}$ . In this model, the $Λ_{c}$ and $Λ_{b}$ excitation spectra are reproduced well, while this model does not explain $Λ_{c} (2765)$ , whose isospin nor spin-parity are unknown yet. Thus, the detailed properties of $Λ_{c} (2765)$ is very important to the presence of the diquark in heavy baryons as a effective constituent. We also discuss the $Ξ_{c}$ spectrum with the scalar strange diquark.
Comments:
17 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1708.02012 [pdf]
PTEP(2017)·16 citations
07
[Submitted on 7 Aug 2017]
Nuclear matter fourth-order symmetry energy in non-relativistic mean-field models
Jie Pu · Zhen Zhang · Lie-Wen Chen
Based on systematic analyses of several popular non-relativistic energy density functionals with mean-field approximation, we estimate the value of the fourth-order symmetry energy $E_{sym,4} (ρ)$ at nuclear normal density $ρ_{0}$ and its density dependence, and explore the correlation between $E_{sym,4} (ρ_{0})$ and other macroscopic quantities of nuclear matter properties. We use the empirical values of some nuclear macroscopic quantities to construct model parameter sets by Monte Carlo method for the conventional Skyrme-Hartree-Fock (SHF) model, the extended Skyrme-Hartree-Fock (eSHF) model, the Gogny-Hartree-Fock (GHF) model, and the momentum-dependent interaction (MDI) model. The value of $E_{sym,4} (ρ_{0})$ is estimated to be $1.02 \pm 0.49$ MeV for the SHF model, $1.02 \pm 0.50$ MeV for the eSHF model, $0.70 \pm 0.60$ MeV for the GHF model, and $0.74 \pm 0.63$ MeV for the MDI model. Moreover, our results indicate that the density dependence of $E_{sym,4} (ρ)$ is model dependent, especially at higher densities. Furthermore, we find that the $E_{sym, 4} (ρ_{0})$ has strong positive (negative) correlation with isoscalar (isovector) nucleon effective mass $m_{s, 0}^{*}$ ( $m_{v, 0}^{*}$ ) at $ρ_{0}$ . In particular, for the SHF and eSHF models, the $E_{sym,4} (ρ)$ is completely determined by the isoscalar and isovector nucleon effective masses $m_{s}^{*} (ρ)$ and $m_{v}^{*} (ρ)$ , and the analytical expression is given. In the mean-field models, the magnitude of $E_{sym,4} (ρ_{0})$ is generally less than $2$ MeV, and its density dependence depends on models, especially at higher densities. $E_{sym,4} (ρ_{0})$ is strongly correlated with $m_{s, 0}^{*}$ and $m_{v, 0}^{*}$ .
Comments:
10 pages, 2 figures, 4 tables. Presentation improved and discussions added. Accepted version to appear in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1708.02132 [pdf]
PRC(2017)·30 citations
08
[Submitted on 7 Aug 2017]
On the Connection Between the Charged and Neutral Pion-Nucleon Coupling Constants in the Yukawa Model
V. A. Babenko🇺🇦 · N. M. Petrov🇺🇦
In the Yukawa model for nuclear forces, a simple relation between the charged and neutral pion-nucleon coupling constants is derived. The relation implies that the charged pion-nucleon coupling constant is larger than the neutral one since the np interaction is stronger than the pp interaction. The derived value of the charged pion-nucleon constant shows a very good agreement with one of the recent experimental values. The relative splitting between the charged and neutral pion-nucleon coupling constants is predicted to be practically the same as that between the charged and neutral pion masses. The charge dependence of the NN scattering length arising from the mass difference between the charged and neutral pions is also analyzed.
Comments:
19 pages. Slightly modified and typos corrected version of the article published in PEPAN Letters
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.02198 [pdf]
Phys.Part.Nucl.Lett.(2017)·8 citations
09
[Submitted on 2 Aug 2017] (cross-list from astro-ph.SR)
The s-process nucleosynthesis: impact of the uncertainties in the nuclear physics determined by Monte Carlo variations
G. Cescutti · N. Nishimura · R. Hirschi · T. Rauscher · J. W. den Hartogh · A. St. J. Murphy
We investigated the impact of uncertainties in neutron-capture and weak reactions (on heavy elements) on the s-process nucleosynthesis in low-mass stars and massive stars using a Monte-Carlo based approach. We performed extensive nuclear reaction network calculations that include newly evaluated temperature-dependent upper and lower limits for the individual reaction rates. We found beta-decay rate uncertainties affect only a few nuclei near s-process branchings, whereas most of the uncertainty in the final abundances is caused by uncertainties in the neutron capture rates. We suggest a list of uncertain rates as candidates for improved measurement by future experiments.
Comments:
Proceedings of the conference "The AGB-Supernovae Mass Transition", held at Rome Observatory, March 27-31, 2017; in press for the Mem. Societa Astronomica Italiana (4 pages, 2 figures, and 1 table). arXiv admin note: text overlap with arXiv:1701.06978
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1708.01629 [pdf]
Mem.Soc.Ast.It.(2017)·1 citation
10
[Submitted on 4 Aug 2017] (cross-list from hep-ph)
Possible Beyond the Standard Model Physics Motivated by Muonic Puzzles
Yu-Sheng Liu🇺🇸
Recent measurements of the proton radius using the Lamb shift in muonic hydrogen are troublingly discrepant with values extracted from hydrogen spectroscopy and electron-proton scattering experiments. This discrepancy, which differs by more than five standard deviations, may be a signal of new physics caused by a violation of lepton universality. Another candidate for a new physics signal is the muon anomalous magnetic moment. The measurement at BNL differs from the standard model prediction by at least three standard deviations. Motivated by these two puzzles, first we use polarized lepton-nucleon elastic scattering to search for a new scalar boson, and furthermore we suggest new measurements of the nucleon form factors. Next, we display a method to analyze the beam dump experiments without using approximation on phase space, and we use it to constrain all possible new spin-0 and spin-1 particles, and a variety of other measurements to study the possibility of the new physics. Finally, assuming a new scalar boson can solve the two puzzles simultaneously, we present a general model-independent analysis and constrain the existence of the new physics.
Comments:
90 pages, 32 figures, PhD thesis, Univ Wash (2017)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1708.01655 [pdf]
2 citations
11
[Submitted on 5 Aug 2017] (cross-list from astro-ph.HE)
Neutrino scattering in supernovae and spin correlations of a unitary gas
Zidu Lin · C. J. Horowitz
Core collapse supernova simulations can be sensitive to neutrino interactions near the neutrinosphere. This is the surface of last scattering. We model the neutrinosphere region as a warm unitary gas of neutrons. A unitary gas is a low density system of particles with large scattering lengths. We calculate modifications to neutrino scattering cross sections because of the universal spin and density correlations of a unitary gas. These correlations can be studied in laboratory cold atom experiments. We find significant reductions in cross sections, compared to free space interactions, even at relatively low densities. These reductions could reduce the delay time from core bounce to successful explosion in multidimensional supernova simulations.
Comments:
5 pages, 2 figures, minor corrections in response to referee, Phys. Rev. C in press
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
1708.01788 [pdf]
PRC(2017)·12 citations
12
[Submitted on 6 Aug 2017] (cross-list from hep-th)
On the hydrodynamic attractor of Yang-Mills plasma
Michał Spaliński🇵🇱
There is mounting evidence suggesting that relativistic hydrodynamics becomes relevant for the physics of quark-gluon plasma as the result of nonhydrodynamic modes decaying to an attractor apparent even when the system is far from local equilibrium. Here we determine this attractor for Bjorken flow in N=4 supersymmetric Yang-Mills theory using Borel summation of the gradient expansion of the expectation value of the energy momentum tensor. By comparing the result to numerical simulations of the flow based on the AdS/CFT correspondence we show that it provides an accurate and unambiguous approximation of the hydrodynamic attractor in this system. This development has important implications for the formulation of effective theories of hydrodynamics.
Comments:
6 pages, 4 figures. v2: many small improvements. v3: introduction rephrased to emphasise key points
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1708.01921 [pdf]
PLB(2018)·103 citations
13
[Submitted on 7 Aug 2017] (cross-list from hep-ph)
Importance of initial and final state effects for azimuthal correlations in p+Pb collisions
Moritz Greif🇩🇪 · Carsten Greiner🇩🇪 · Björn Schenke🇺🇸 · Sören Schlichting🇺🇸 · Zhe Xu🇨🇳
We investigate the relative importance of initial and final state effects on azimuthal correlations of gluons in low and high multiplicity p+Pb collisions. To achieve this, we couple Yang-Mills dynamics of pre-equilibrium gluon fields (IP-GLASMA) to a perturbative QCD based parton cascade for the final state evolution (BAMPS) on an event-by-event basis. We find that signatures of both the initial state correlations and final state interactions are seen in azimuthal correlation observables, such as $v_{2} {2 P C} (p_{T})$ , their strength depending on the event multiplicity and transverse momentum. Initial state correlations dominate $v_{2} {2 P C} (p_{T})$ in low multiplicity events for transverse momenta $p_{T} > 2 GeV$ . While final state interactions are dominant in high multiplicity events, initial state correlations affect $v_{2} {2 P C} (p_{T})$ for $p_{T} > 2 GeV$ as well as the pT integrated $v_{2} {2 P C}$ .
Comments:
6 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1708.02076 [pdf]
PRD(2017)·84 citations

Affiliations

first authorsco-authorsvia INSPIRE