Nuclear Theory·nucl-th

Wednesday·April 29, 2015

12 papers—6 primary·6 cross-listed

01
[Submitted on 28 Apr 2015]
Hadronic Matter in the Robertson-Walker Metric and the Early Universe
Ivan E. Cunha🇧🇷 · Celso C. Barros Jr🇧🇷
In this work, the Friedman equations for hadronic matter in the Robertson-Walker metric in the early Universe are obtained. We consider the hadronic phase, formed after the hadronization of the quark-gluon plasma, that means times from 10^{-6}s to 1s. The set of equations is derived and the behavior of the system is studied considering one approximate analytical solution.
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Theory (hep-th)
arXiv:
1504.07314 [pdf]
Phys.Part.Nucl.Lett.(2019)·1 citation
02
[Submitted on 28 Apr 2015]
Magnetic moment, vorticity-spin coupling and parity-odd conductivity of chiral fermions in 4-dimensional Wigner functions
Jian-hua Gao🇨🇳 · Qun Wang🇨🇳
We demonstrate the emergence of the magnetic moment and spin-vorticity coupling of chiral fermions in 4-dimensional Wigner functions. In linear response theory with space-time varying electromagnetic fields, the parity-odd part of the electric conductivity can also be derived which reproduces results of the one-loop and the hard-thermal or hard-dense loop. All these properties show that the 4-dimensional Wigner functions capture comprehensive aspects of physics for chiral fermions in electromagnetic fields.
Comments:
RevTex 4, 5 pages, no figure. Appendix A and B are added about derivation of Eq.(7) and about Wigner functions in space-time varying electromagnetic fields. Accepted by PLB
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.07334 [pdf]
PLB(2015)·31 citations
03
[Submitted on 28 Apr 2015]
A Simple Efficient Method for Obtaining the Binding Energy of Lithium Nucleus under the Hulthén and Inversely Quadratic Yukawa Potentials
Nasrin. Salehi🇮🇷 · Mahsa. Ghazvini🇮🇷
In this paper, the binding energy of Lithium nucleus in a nonrelativistic model is obtained for the Hulthén and the Inversely Quadratic Yukawa Potential. In order to that, we used the concept of supersymmetry to solving the Schrödinger equation exact analytically. These potentials, due to their physical interpretations, are of interest within many areas of theoretical physics. The results of our model for all calculations show that the ground state binding energy of Lithium nucleus with these potentials are very close to the ones obtained in experiments.
Comments:
arXiv admin note: substantial text overlap with arXiv:1407.2200
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.07359 [pdf]
0 citations
04
[Submitted on 28 Apr 2015]
Vibrational and rotational excited states within Bohr Hamiltonian with deformation-dependent mass formalism
M. Chabab · A. Lahbas · M. Oulne
In a recent work (Phys.Rev.C84, 044321, 2011) M.J. Ermamatov and P.R. Fraser have studied rotational and vibrational excited states of axially symmetric nuclei within the Bohr Hamiltonian with different mass parameters. However, the energy formula that the authors have used contains some inaccuracies. So, the numerical results they obtained seem to be controversial. In this paper, we revisit all calculations related to this problem and determine the appropriate formula for the energy spectrum. Moreover, in order to improve such calculations, we reconsider this problem within the framework of the deformation dependent mass formalism. Also, unlike the work of Bonatsos et al. (Phys.Rev.C83, 044321, 2011) where the mass parameter has not been considered, we will show the importance of this parameter and its effect on numerical predictions.
Comments:
19 pages, 11 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.07410 [pdf]
PRC(2015)·37 citations
05
[Submitted on 28 Apr 2015]
Further evidence for three-nucleon spin-orbit interaction in isotope shifts of $Z = magic$ nuclei
H. Nakada
It was pointed out [Phys. Rev. C \textbf{91}, 021302(R)] that the isotope shifts of the Pb nuclei, the kink at $N = 126$ in particular, can be well described by the Hartree-Fock-Bogolyubov calculations if a density-dependent LS interaction derived from the $3 N$ interaction is incorporated. Effects of the density-dependence in the LS channel on the isotope shifts are extensively investigated for the Ca, Ni and Sn isotopes, using the semi-realistic M3Y-P6 interaction and its LS modified variant M3Y-P6a, as in the Pb case. It is found that almost equal charge radii between $^{40}$ Ca and $^{48}$ Ca are reproduced, as well as the isotope shifts in a long chain of the Sn nuclei, owing to the density-dependence in the LS channel. A kink is predicted at $N = 82$ for the isotope shifts of the Sn nuclei, in clear contrast to the interactions without the density-dependence.
Comments:
7 pages including 4 figures, to appear in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.07445 [pdf]
PRC(2015)·40 citations
06
[Submitted on 28 Apr 2015]
Role of $Λ (1670)$ in the $γ p \to K^{+} η Λ$ reaction near threshold
Li-Ye Xiao🇨🇳 · Qi-Fang Lü🇨🇳 · Ju-Jun Xie🇨🇳 · Xian-Hui Zhong🇨🇳
The role of the $Λ (1670)$ resonance in the $γ p \to K^{+} η Λ$ reaction near threshold is studied within an effective Lagrangian approach. We perform a calculation for the total and differential cross section of the $γ p \to K^{+} η Λ$ reaction by including the contributions from the $Λ (1670)$ intermediate state decaying into $η Λ$ dominated by $K^{-}$ and $K^{*-}$ mesons exchanges, the nucleon pole and $N^{*} (1535)$ resonance decaying into $K^{+} Λ$ dominated by exchanges of $ω$ and $K^{-}$ mesons. Besides, the non-resonance process and contact terms to keep the total scattering amplitude gauge invariant are also considered. With our model parameters, the total cross section of this reaction is of the order of $1$ nanobarn at photon beam energy $E_{γ} \sim 2.5$ GeV. It is expected that our model predictions could be tested by future experiments.
Comments:
Published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1504.07535 [pdf]
EPJA(2015)·6 citations
07
[Submitted on 28 Apr 2015] (cross-list from hep-ph)
Comparative study of the scalar- and tensor-meson production in the reaction $γ γ^{*} (Q^{2}) \to η π^{0}$
N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺 · G.N. Shestakov🇷🇺
The prediction of the cross section $σ (γ γ^{*} (Q^{2}) \to η π^{0})$ based on the simultaneous description of the Belle data on the $γ γ \to η π^{0}$ reaction and the KLOE data on the $ϕ \to η π^{0} γ$ decay is presented. The production of the scalar $a_{0} (980)$ and tensor $a_{2} (1320)$ is studied in detail. It is shown that the QCD based asymptotics of the $γ^{*} (Q^{2}) γ \to a_{2} (1320) \to η π^{0}$ cross section can be reached by the compensation of the contributions of $ρ (770)$ and $ω (782)$ with the contributions of their radial excitations in $Q^{2}$ channel. At large $Q^{2}$ the $a_{2} (1320)$ contribution is expected to be dominant, while at $Q^{2} = 0$ it is similar to the scalars contribution.
Comments:
27 pages, 12 figures. The text is clarified, some other changes are done
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1504.07346 [pdf]
Phys.Atom.Nucl.(2016)·6 citations
08
[Submitted on 28 Apr 2015] (cross-list from hep-ph)
Quarkonium suppression from coherent energy loss in fixed-target experiments using LHC beams
François Arleo🇫🇷 · Stéphane Peigné🇫🇷
Quarkonium production in proton-nucleus collisions is a powerful tool to disentangle cold nuclear matter effects. A model based on coherent energy loss is able to explain the available quarkonium suppression data in a broad range of rapidities, from fixed-target to collider energies, suggesting cold energy loss to be the dominant effect in quarkonium suppression in p-A collisions. This could be further tested in a high-energy fixed-target experiment using a proton or nucleus beam. The nuclear modification factors of J/ $ψ$ and $Υ$ as a function of rapidity are computed in p-A collisions at $s = 114.6$ GeV, and in p-Pb and Pb-Pb collisions at $s = 72$ GeV. These center-of-mass energies correspond to the collision on fixed-target nuclei of 7 TeV protons and 2.76 TeV lead nuclei available at the LHC.
Comments:
7 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1504.07428 [pdf]
Adv.High Energy Phys.(2015)·13 citations
09
[Submitted on 28 Apr 2015] (cross-list from hep-ph)
Euler-Heisenberg-Weiss action for QCD+QED
Sho Ozaki🇯🇵 · Takashi Arai🇯🇵 · Koichi Hattori🇯🇵 · Kazunori Itakura🇯🇵
We derive an analytic expression for one-loop effective action of QCD+QED at zero and finite temperatures by using the Schwinger's proper time method. The result is a nonlinear effective action not only for electromagnetic and chromo-electromagnetic fields but also the Polyakov loop, and thus reproduces the Euler-Heisenberg action in QED, QCD, and QED+QCD, and also the Weiss potential for the Polyakov loop at finite temperature. As applications of this "Euler-Heisenberg-Weiss" action in QCD+QED, we investigate quark pair productions induced by QCD+QED fields at zero temperature and the Polyakov loop in the presence of strong electromagnetic fields. Quark one-loop contribution to the effective potential of the Polyakov loop explicitly breaks the center symmetry, and is found to be enhanced by the magnetic field, which is consistent with the inverse magnetic catalysis observed in lattice QCD simulation.
Comments:
36 pages, 10 figures, version published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1504.07532 [pdf]
PRD(2015)·17 citations
10
[Submitted on 28 Apr 2015] (cross-list from hep-ph)
Understanding of QCD at high density from Z3-symmetric QCD-like theory
Hiroaki Kouno🇯🇵 · Kouji Kashiwa🇯🇵 · Junichi Takahashi🇯🇵 · Tatsuhiro Misumi🇯🇵 · Masanobu Yahiro🇯🇵
We investigate QCD at large mu/T by using Z_3-symmetric SU(3) gauge theory, where mu is the quark-number chemical potential and T is temperature. We impose the flavor-dependent twist boundary condition on quarks in QCD. This QCD-like theory has the twist angle theta as a parameter, and agrees with QCD when theta=0 and becomes symmetric when theta=2\pi/3. For both QCD and the Z_3-symmetric SU(3) gauge theory, the phase diagram is drawn in mu--T plane with the Polyakov-loop extended Nambu--Jona-Lasinio model. In the Z_3-symmetric SU(3) gauge theory, the Polyakov loop varphi is zero in the confined phase appearing at T \lsim 200 MeV. The perfectly confined phase never coexists with the color superconducting (CSC) phase, since finite diquark condensate in the CSC phase breaks Z_3 symmetry and then makes varphi finite. When mu \gsim 300 MeV, the CSC phase is more stable than the perfectly confined phase at T \lsim 100 MeV. Meanwhile, the chiral symmetry can be broken in the perfectly confined phase, since the chiral condensate is Z_3 invariant. Consequently, the perfectly confined phase is divided into the perfectly confined phase without chiral symmetry restoration in a region of mu \lsim 300 MeV and T \lsim 200 MeV and the perfectly confined phase with chiral symmetry restoration in a region of \mu \gsim 300 MeV and 100 \lsim T \lsim 200 MeV. The basic phase structure of Z_3-symmetric QCD-like theory remains in QCD. We show that in the perfectly confined phase the sign problem becomes less serious because of \varphi=0, using the heavy quark theory. We discuss a lattice QCD framework to evaluate observables at \theta=0 from those at \theta=2\pi/3.
Comments:
8 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1504.07585 [pdf]
PRD(2016)·33 citations
11
[Submitted on 28 Apr 2015] (cross-list from astro-ph.HE)
The Fate of the Compact Remnant in Neutron Star Mergers
Chris L. Fryer🇺🇸 · Krzysztoff Belczynski🇵🇱 · Enrico Ramirez-Ruiz🇺🇸 · Stephan Rosswog🇸🇪 · Gang Shen🇺🇸 · Andrew W. Steiner🇺🇸
Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.
Comments:
12 pages, submitted to ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1504.07605 [pdf]
ApJ(2015)·86 citations
12
[Submitted on 28 Apr 2015] (cross-list from hep-ph)
QCD Kondo effect: quark matter with heavy-flavor impurities
Koichi Hattori🇯🇵 · Kazunori Itakura🇯🇵 · Sho Ozaki🇯🇵 · Shigehiro Yasui🇯🇵
We show that the Kondo effect occurs in light quark matter which contains heavy quarks as impurities. We consider a scattering between a heavy-flavor impurity and a light quark near a Fermi surface which is mediated by gluon-exchange interactions. We find that the scattering amplitude has a logarithmic infrared divergence originating from imperfect cancellation between quark-impurity and hole-impurity scatterings in a loop integral, implying the presence of a strongly coupled regime near the Fermi surface. Renormalization group method is used to find the Kondo scale where a running coupling constant hits a Landau pole. Following an illustration by a simple contact-interaction model, we examine gluon-exchange interactions on the basis of high density QCD.
Comments:
11 pages, 4 figures. Errors corrected; Results unchanged; Extended discussions inserted in Sec. IV; References added. Published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
1504.07619 [pdf]
PRD(2015)·55 citations

Affiliations

first authorsco-authorsvia INSPIRE