Nuclear Theory·nucl-th

Tuesday·May 3, 2016

13 papers—9 primary·4 cross-listed

01
[Submitted on 30 Apr 2016]
Electric dipole moment of the deuteron in the standard model with $N N - Λ N - Σ N$ coupling
Nodoka Yamanaka
We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $∣Δ S ∣ = 1$ interactions by taking into account the $N N - Λ N - Σ N$ channel coupling, which is an important nuclear level systematics. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v 18$ nuclear force and the $Y N$ potential which can reproduce the binding energies of $_{Λ}^{3}$ H, $_{Λ}^{3}$ He, and $_{Λ}^{4}$ He. The $∣Δ S ∣ = 1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $Y N$ interaction is small, and treating $Λ N$ and $Σ N$ channels as free is a good approximation for the EDM of the deuteron.
Comments:
12 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1605.00161 [pdf]
NPA(2017)·27 citations
02
[Submitted on 1 May 2016]
First clear evidence of quantum chaos in the bound states of an atomic nucleus
L. Muñoz · R. A. Molina · J.M.G. Gómez · A. Heusler
We study the spectral fluctuations of the $^{208}$ Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of $6.20$ MeV recently identified at the Maier-Leibnitz-Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of Random Matrix Theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter $ω$ , which takes the value $ω = 0$ for regular systems and $ω ≃ 1$ for chaotic systems. We obtain $ω = 0.85 \pm 0.02$ which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in $^{208}$ Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition our results show that chaotic and non-chaotic nuclear states coexist in the same energy region of the spectrum.
Comments:
9 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1605.00210 [pdf]
PRC(2017)·13 citations
03
[Submitted on 1 May 2016]
Electromagnetic response of 12C: a first-principles calculation
A. Lovato🇺🇸 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸 · Steven C. Pieper🇺🇸 · R. Schiavilla🇺🇸
The longitudinal and transverse electromagnetic response functions of $^{12}$ C are computed in a "first-principles" Green's function Monte Carlo calculation, based on realistic two- and three-nucleon interactions and associated one- and two-body currents. We find excellent agreement between theory and experiment and, in particular, no evidence for the quenching of measured versus calculated longitudinal response. This is further corroborated by a re-analysis of the Coulomb sum rule, in which the contributions from the low-lying $J^{π}$ = $2^{+}$ , $0_{2}^{+}$ (Hoyle), and $4^{+}$ states in $^{12}$ C are accounted for explicitly in evaluating the total inelastic strength.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex)
arXiv:
1605.00248 [pdf]
PRL(2016)·120 citations
04
[Submitted on 2 May 2016]
Isospin decomposition of $γ N \to N^{*}$ transitions within a dynamical coupled-channels model
H. Kamano🇯🇵 · S. X. Nakamura🇯🇵 · T.-S. H. Lee🇺🇸 · T. Sato🇯🇵
By extending the dynamical coupled-channels analysis performed in our previous work [Phys. Rev. C 88, 035209 (2013)] to include the available data of photoproduction of pi meson off the neutron, the transition amplitudes for the photo-excitation of the neutron to nucleon resonances, gamma n --> N*, at the resonance pole positions are determined. The combined fits to the data for both the proton- and neutron-target reactions also revise our results for the resonance pole positions and the gamma p --> N* transition amplitudes. Our results allow an isospin decomposition of the gamma N --> N* transition amplitudes for the isospin I=1/2 N* resonances, which is necessary for testing hadron structure models and gives crucial inputs for constructing models of neutrino-induced reactions in the nucleon resonance region.
Comments:
20 pages, 12 figures. Typos, equations, and numerical values in Tables are corrected
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1605.00363 [pdf]
PRC(2016)·77 citations
05
[Submitted on 2 May 2016]
A ferro-deformation at the open quantum system with protons, Z = 8, neutrons, N = 20: 28O
Chang-Bum Moon
We offer a possibility that the nuclear system with protons, Z = 8 has a large deformation at neutrons, N = 20; 28O that is beyond the neutron drip line. According to our previous works [arXiv: 1604.05013, 1604.02786, 1604.01017], it is expected that the ferro-deformation would occur at Z = 8, N = 20 through a shape phase transition at N = 18 out of N =16. The shape transition can be explained in terms of isospin dependent spin-orbital interactions between neutrons in the d3/2 orbital and protons in the d5/2 orbital, by yielding both the neutron and the proton pseudo-shell configurations built on each combined subshells. We argue that such a large deformation at N = 18 would be responsible for the 26O to be unbound, leading to a ground state neutron emitter. The ferro-deformation is mapped on the nuclear chart such that is around the following critical proton, neutron coordinates, (Z, N); (64, 104), (40, 64), (20, 40), (8, 20). This configuration depicts a beautiful pattern coming from a harmonious order in the microscopic quantum world.
Comments:
7 pages, 5 figures, national nuclear data center (NNDC), magic numbers, pseudo-shell, ferro-deformation
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1605.00370 [pdf]
2 citations
06
[Submitted on 2 May 2016]
N3LO NN interaction adjusted to light nuclei in ab exitu approach
A. M. Shirokov🇺🇸 · I. J. Shin🇰🇷 · Y. Kim🇰🇷 · M. Sosonkina🇺🇸 · P. Maris🇺🇸 · J. P. Vary🇺🇸
We use phase-equivalent transformations to adjust off-shell properties of similarity renormalization group evolved chiral effective field theory NN interaction (Idaho N3LO) to fit selected binding energies and spectra of light nuclei in an ab exitu approach. We then test the transformed interaction on a set of additional observables in light nuclei to verify that it provides reasonable descriptions of these observables with an apparent reduced need for three- and many-nucleon interactions.
Comments:
Revised text due to journal referee comments. 6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.00413 [pdf]
PLB(2016)·141 citations
07
[Submitted on 2 May 2016]
Theoretical study of the $α + d$ $\to$ $^{6}$ Li + $γ$ astrophysical capture process in a three-body model
E.M. Tursunov (INP, Tashkent) · A.S. Kadyrov (Curtin University) · S.A. Turakulov (INP, Tashkent) · I. Bray (Curtin University)
The astrophysical capture process $α + d$ $\to$ $^{6}$ Li + $γ$ is studied in a three-body model. The initial state is factorized into the deuteron bound state and the $α + d$ scattering state. The final nucleus $^{6}$ Li(1+) is described as a three-body bound state $α + n + p$ in the hyperspherical Lagrange-mesh method. The contribution of the E1 transition operator from the initial isosinglet states to the isotriplet components of the final state is estimated to be negligible. An estimation of the forbidden E1 transition to the isosinglet components of the final state is comparable with the corresponding results of the two-body model. However, the contribution of the E2 transition operator is found to be much smaller than the corresponding estimations of the two-body model. The three-body model perfectly matches the new experimental data of the LUNA collaboration with the spectroscopic factor 2.586 estimated from the bound-state wave functions of $^{6}$ Li and deuteron.
Comments:
14 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1605.00484 [pdf]
PRC(2016)·29 citations
08
[Submitted on 2 May 2016]
Strangeness in nuclear physics
A. Gal🇮🇱 · E.V. Hungerford🇺🇸 · D.J. Millener🇺🇸
Extensions of nuclear physics to the strange sector are reviewed, covering data and models of Lambda and other hypernuclei, multi-strange matter, and anti-kaon bound states and condensation. Past achievements are highlighted, present unresolved problems discussed, and future directions outlined.
Comments:
65 pages, 44 figures, published as Reviews of Modern Physics 88, 035004 (2016)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1605.00557 [pdf]
RMP(2016)·545 citations
09
[Submitted on 2 May 2016]
Neutrinos in Astrophysics and Cosmology
A.B. Balantekin (Wisconsin U., Madison)🇺🇸
Neutrinos play a crucial role in many aspects of astrophysics and cosmology. Since they control the electron fraction, or equivalently neutron-to-proton ratio, neutrino properties impact yields of r-process nucleosynthesis. Similarly the weak decoupling temperature in the Big Bang Nucleosynthesis epoch is exponentially dependent on the neutron-to-proton ratio. In these conference proceedings, I briefly summarize some of the recent work exploring the role of neutrinos in astrophysics and cosmology.
Comments:
6 pages, Proceedings of IX International Conference on Interconnections between Particle Physics and Cosmology (PPC2015)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.00578 [pdf]
AIP Conf.Proc.(2016)·4 citations
10
[Submitted on 29 Apr 2016] (cross-list from hep-ph)
$Z_{c} (3900)$ as a $D D ˉ^{*}$ molecule from the pole counting rule
Qin-Rong Gong🇨🇳 · Zhi-Hui Guo🇨🇳 · Ce Meng🇨🇳 · Guang-Yi Tang🇨🇳 · Yu-Fei Wang🇨🇳 · Han-Qing Zheng🇨🇳
A comprehensive study on the nature of the $Z_{c} (3900)$ resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the $J / ψ π$ and $π π$ invariant mass distributions from the $e^{+} e^{-} \to J / ψ π π$ process, the $h_{c} π$ distribution from $e^{+} e^{-} \to h_{c} π π$ and also the $D D ˉ^{*}$ spectrum in the $e^{+} e^{-} \to D D ˉ^{*} π$ process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and find only one pole in the nearby energy region in different Riemann sheets. Therefore we conclude that $Z_{c} (3900)$ is of $D D ˉ^{*}$ molecular nature, according to the pole counting rule method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We emphasize that the conclusion based upon the pole counting method is not trivial, since both the $D D ˉ^{*}$ contact interactions and the explicit $Z_{c}$ exchanges are introduced in our analyses and they lead to the same conclusion.
Comments:
21 pages, 9 figures. To match the published version in PRD. Additional discussion on the spectral density function is included
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1604.08836 [pdf]
PRD(2016)·47 citations
11
[Submitted on 29 Apr 2016] (cross-list from cond-mat.quant-gas)
String-Theory-Based Predictions for Nonhydrodynamic Collective Modes in Strongly Interacting Fermi Gases
H. Bantilan🇬🇧 · J.T. Brewer🇺🇸 · T. Ishii🇺🇸 · W.E. Lewis🇺🇸 · P. Romatschke🇺🇸
Very different strongly interacting quantum systems such as Fermi gases, quark-gluon plasmas formed in high energy ion collisions and black holes studied theoretically in string theory are known to exhibit quantitatively similar damping of hydrodynamic modes. It is not known if such similarities extend beyond the hydrodynamic limit. Do non-hydrodynamic collective modes in Fermi gases with strong interactions also match those from string theory calculations? In order to answer this question, we use calculations based on string theory to make predictions for novel types of modes outside the hydrodynamic regime in trapped Fermi gases. These predictions are amenable to direct testing with current state-of-the-art cold atom experiments.
Comments:
8 pages, 2 figures, 2 tables; v2: matches published version
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1605.00014 [pdf]
PRA(2016)·8 citations
12
[Submitted on 1 May 2016] (cross-list from hep-ph)
Jet quenching parameter of quark-gluon plasma in strong magnetic field: Perturbative QCD and AdS/CFT correspondence
Shiyong Li🇺🇸 · Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸
We compute the jet quenching parameter $q^$ of QCD plasma in the presence of strong magnetic field in both weakly and strongly coupled regimes. In weakly coupled regime, we compute $q^$ in perturbative QCD at complete leading order (that is, leading log as well as the constant under the log) in QCD coupling constant $α_{s}$ , assuming the hierarchy of scales $α_{s} e B ≪ T^{2} ≪ e B$ . We consider two cases of jet orientations with respect to the magnetic field: 1) the case of jet moving parallel to the magnetic field, 2) the case jet moving perpendicular to the magnetic field. In the former case, we find $q^\sim α_{s}^{2} (e B) T lo g (1/ α_{s})$ , while in the latter we have $q^\sim α_{s}^{2} (e B) T lo g (T^{2} / α_{s} e B)$ . In both cases, this leading order result arises from the scatterings with thermally populated lowest Landau level quarks. In strongly coupled regime described by AdS/CFT correspondence, we find $q^\sim λ (e B) T$ or $q^\sim λ e B T^{2}$ in the same hierarchy of $T^{2} ≪ e B$ depending on whether the jet is moving parallel or perpendicular to the magnetic field, respectively, which indicates a universal dependence of $q^$ on $(e B) T$ in both regimes for the parallel case, the origin of which should be the transverse density of lowest Landau level states proportional to $e B$ . Finally, the asymmetric transverse momentum diffusion in the case of jet moving perpendicular to the magnetic field may give an interesting azimuthal asymmetry of the gluon Bremsstrahlung spectrum in the BDMPS-Z formalism.
Comments:
39 pages, 2 figures; v2: two minor typos fixed, a reference added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1605.00188 [pdf]
PRD(2016)·51 citations
13
[Submitted on 2 May 2016] (cross-list from nucl-ex)
Accessing proton generalized parton distributions and pion distribution amplitudes with the exclusive pion-induced Drell-Yan process at J-PARC
Takahiro Sawada🇹🇼 · Wen-Chen Chang🇹🇼 · Shunzo Kumano🇯🇵 · Jen-Chieh Peng🇺🇸 · Shinya Sawada🇯🇵 · Kazuhiro Tanaka🇯🇵
Generalized parton distributions (GPDs) encoding multidimensional information of hadron partonic structure appear as the building blocks in a factorized description of hard exclusive reactions. The nucleon GPDs have been accessed by deeply virtual Compton scattering and deeply virtual meson production with lepton beam. A complementary probe with hadron beam is the exclusive pion-induced Drell-Yan process. In this paper, we discuss recent theoretical advances on describing this process in terms of nucleon GPDs and pion distribution amplitudes. Furthermore, we address the feasibility of measuring the exclusive pion-induced Drell-Yan process $π^{-} p \to μ^{+} μ^{-} n$ via a spectrometer at the High Momentum Beamline being constructed at J-PARC in Japan. Realization of such measurement at J-PARC will provide a new test of perturbative QCD descriptions of a novel class of hard exclusive reactions. It will also offer the possibility of experimentally accessing nucleon GPDs at large timelike virtuality.
Comments:
35 pages and 16 figures. Replaced with published version. Added the journal reference and DOI
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.00364 [pdf]
PRD(2016)·63 citations

Affiliations

first authorsco-authorsvia INSPIRE