Nuclear Theory·nucl-th

Tuesday·March 17, 2015

9 papers—5 primary·4 cross-listed

01
[Submitted on 14 Mar 2015]
Alpha cluster structures and monopole excitations in $^{13}$ C
Taiichi Yamada · Yasuro Funaki
The structure of $1/ 2^{\pm}$ states in $^{13}$ C up to around the $3 α + n$ threshold ( $E_{x} = 12.3$ ~MeV) is investigated with a full four-body $3 α + n$ orthogonality condition model (OCM) calculation, where the $3 α$ OCM, the model space of which is the subspace of the $3 α + n$ model, describes well the structure of the low-lying states of $^{12}$ C including the $2_{2}^{+}$ , $0_{3}^{+}$ , and $0_{4}^{+}$ states, which have been recently observed above the Hoyle state ( $0_{2}^{+}$ ). A full spectrum up to the $1/ 2_{5}^{-}$ ( $1/ 2_{3}^{+}$ ) state is reproduced consistently with the lowest five $1/ 2^{-}$ (three $1/ 2^{+}$ ) states of experimental spectrum. It is shown that the $1/ 2_{2}^{-}$ and $1/ 2_{3}^{-}$ states are characterized by the dominant cluster configurations of $^{9}$ Be( $3/ 2^{-}$ , $1/ 2^{-}$ )+ $α$ , while the ground state $1/ 2_{1}^{-}$ has a shell-model-like structure. The observed monopole transition strengths to the $1/ 2_{2, 3}^{-}$ states are consistently reproduced for the first time. These results indicate that the excited $1/ 2^{-}$ states have cluster structures. They are compared to those by the previous work with the shell model. On the other hand, the $1/ 2_{1}^{+}$ state is found to have a loosely bound neutron structure in which the extra neutron moves around $^{12}$ C(g.s) core with $1 S$ orbit, reflecting the fact that this state appears by $1.9$ MeV just below the $^{12}$ C(g.s)+ $n$ threshold, while the $1/ 2_{2}^{+}$ and $1/ 2_{3}^{+}$ states are characterized by $^{9}$ Be+ $α$ structures. We found that the $1/ 2_{5}^{+}$ state located above the $3 α + n$ threshold is the Hoyle analogue state in $^{13}$ C, the wave function of which is described by product states of constituent clusters, $(0 S)_{α}^{3} (S)_{n}$ , with the probability of $52$ %.
Comments:
39 pages, 9 figures, version accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04261 [pdf]
PRC(2015)·56 citations
02
[Submitted on 14 Mar 2015]
Spectrum of resonance states in $^{6}$ He. Experimental and theoretical analysis
O. M. Povoroznyk · V. S. Vasilevsky
We explore the structure of resonance states in $^{6}$ He by experimental and theoretical methods. We present the results of experimental investigations of the three-body continuous spectrum of $^{6}$ He. For this aim, we use the reaction $^{3}$ H $(α, p α) nn$ , which is induced by the interaction of alpha-particles with a triton at the beam energy $E_{α} =$ ~67.2 MeV. The theoretical analysis of the resonance structure in $^{6}$ He is carried out within the framework of a three-cluster microscopic model. The model exploits the hyperspherical harmonics to describe the intercluster dynamics. The set of new resonance states is discovered by the experimental and theoretical methods. The energy, width, and dominant decay channels of resonances are determined.The obtained results are compared in detail with the results of different theoretical models and experiments as well.
Comments:
16 pp, 17 figures, UJP style file provided
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04308 [pdf]
Ukr.J.Phys.(2015)·4 citations
03
[Submitted on 15 Mar 2015]
Production of heavy neutron-rich nuclei in transfer reactions within the dinuclear system model
Long Zhu🇨🇳 · Zhao-Qing Feng🇨🇳 · Feng-Shou Zhang🇨🇳
The dynamics of nucleon transfer processes in heavy-ion collisions is investigated within the dinuclear system model. The production cross sections of nuclei in the reactions $^{136}$ Xe+ $^{208}$ Pb and $^{238}$ U+ $^{248}$ Cm are calculated and the calculations are in good agreement with the experimental data. The transfer cross sections for the $^{58}$ Ni+ $^{208}$ Pb reaction are calculated and compared with the experimental data. We predict the production cross sections of neutron-rich nuclei $^{165 - 168}$ Eu, $^{169 - 173}$ Tb, $^{173 - 178}$ Ho, and $^{181 - 185}$ Yb based on the reaction $^{176}$ Yb+ $^{238}$ U. It can be seen that the production cross sections of the neutron-rich nuclei $^{165}$ Eu, $^{169}$ Tb, $^{173}$ Ho, and $^{181}$ Yb are 2.84 $μ$ b, 6.90 $μ$ b, 46.24 $μ$ b, and 53.61 $μ$ b, respectively, which could be synthesized in experiment.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1503.04421 [pdf]
J.Phys.G(2015)·49 citations
04
[Submitted on 15 Mar 2015]
Enhancement of the CP-odd effect in the nuclear electric dipole moment of $^{6}$ Li
Nodoka Yamanaka🇯🇵 · Emiko Hiyama🇯🇵
We calculate for the first time the electric dipole moment (EDM) of the $^{6}$ Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the $^{6}$ Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The $^{9}$ Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^{3}$ H and $^{3}$ He nuclei using the realistic Argonne $v 18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.
Comments:
6 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1503.04446 [pdf]
PRC(2015)·59 citations
05
[Submitted on 16 Mar 2015]
Search for octupole correlations in $^{147}$ Nd
E. Ruchowska · H. Mach · M. Kowal · J. Skalski · W. A. Plociennik · B. Fogelberg
Properties of excited states in $^{147}$ Nd have been studied with multispectra and $γ γ$ coincidence measurements. Twenty-four new $γ$ -lines and three new levels have been introduced into the level scheme of $^{147}$ Nd. Lifetimes of eight excited levels in $^{147}$ Nd, populated in the $β$ decay of $^{147}$ Pr, have been measured using the advanced time-delayed $β γ γ$ (t) method. Reduced transition probabilities have been determined for 30 $γ$ -transitions in $^{147}$ Nd. Potential energy surfaces on the ( $β_{2}$ , $β_{3}$ ) plane calculated for $^{147}$ Nd using the Strutinsky method predict two single quasiparticle configurations with nonzero octupole deformation, with K=1/2 and K=5/2. We do not observe parity doublet bands with K=5/2. For pair of opposite parity bands that could form the K=1/2 parity doublet we were able only to determine lower limit of the dipole moment, $∣ D_{0} ∣ \geq$ 0.02 e $\cdot f m$ .
Comments:
Submitted to PRC
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04606 [pdf]
PRC(2015)·9 citations
06
[Submitted on 13 Mar 2015] (cross-list from hep-ph)
A Modest Revision of the Standard Model
G. J. Stephenson Jr.🇺🇸 · T. Goldman🇺🇸
With a modest revision of the mass sector of the Standard Model, the systematics of the fermion masses and mixings can be fully described and interpreted as providing information on matrix elements of physics beyond the Standard Model. A by-product is a reduction of the largest Higgs Yukawa fine structure constant by an order of magnitude. The extension to leptons provides for insight on the difference between quark mixing and lepton mixing as evidenced in neutrino oscillations. The large difference between the scale for up-quark and down-quark masses is not addressed. In this approach, improved detail and accuracy of the elements of the current mixing matrices can extend our knowledge and understanding of physics beyond the Standard Model.
Comments:
36 pages, 2 figures. Pedagogical appendix removed; typos corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1503.04211 [pdf]
2 citations
07
[Submitted on 16 Mar 2015] (cross-list from hep-ph)
Relativistic hydrodynamics from quantum field theory on the basis of the generalized Gibbs ensemble method
Tomoya Hayata🇯🇵 · Yoshimasa Hidaka🇯🇵 · Masaru Hongo🇯🇵 · Toshifumi Noumi🇯🇵
We derive relativistic hydrodynamics from quantum field theories by assuming that the density operator is given by a local Gibbs distribution at initial time. We decompose the energy-momentum tensor and particle current into nondissipative and dissipative parts, and analyze their time evolution in detail. Performing the path-integral formulation of the local Gibbs distribution, we microscopically derive the generating functional for the nondissipative hydrodynamics.We also construct a basis to study dissipative corrections. In particular, we derive the first-order dissipative hydrodynamic equations without a choice of frame such as the Landau-Lifshitz or Eckart frame.
Comments:
29 pages, 3 figures (2 figures are added), published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1503.04535 [pdf]
PRD(2015)·72 citations
08
[Submitted on 16 Mar 2015] (cross-list from hep-ph)
Collective String Interactions in AdS/QCD and High-Multiplicity pA Collisions
Ioannis Iatrakis🇺🇸 · Adith Ramamurti🇺🇸 · Edward Shuryak🇺🇸
QCD strings originate from high-energy scattering in the form of Reggeons and Pomerons, and have been studied in some detail in lattice numerical simulations. Production of multiple strings, with their subsequent breaking, is now a mainstream model of high energy $pp$ and $p A$ collisions. Recent LHC experiments revealed that high multiplicity end of such collisions show interesting collective effects. This ignited an interest in the interaction of QCD strings and multi-string dynamics. Holographic models, collectively known as AdS/QCD, developed in the last decade, describe both hadronic spectroscopy and basic thermodynamics, but so far no studies of the QCD strings have been done in this context. The subject of this paper is to do this. First, we study in more detail the scalar sector of hadronic spectroscopy, identifying "glueballs" and "scalar mesons," and calculate the degree of their mixing. The QCD strings, holographic images of the fundamental strings, thus have a "gluonic core" and a "sigma cloud." The latter generates $σ$ exchanges and collectivization of the strings, affecting, at a certain density, the chiral condensate and even the minimum of the effective string potential, responsible for the very existence of the QCD strings. Finally, we run dynamical simulations of the multi-string systems, in the "spaghetti" setting approximating central $p A$ collisions, and specify conditions for their collectivization into a black hole, or the dual QGP fireball.
Comments:
14 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1503.04759 [pdf]
PRD(2015)·18 citations
09
[Submitted on 16 Mar 2015] (cross-list from hep-ph)
Galilean-Invariant XEFT
Eric Braaten🇺🇸
XEFT is a low-energy effective field theory for charm mesons and pions that provides a systematically improvable description of the X(3872) resonance. A Galilean-invariant formulation of XEFT is introduced to exploit the fact that mass is very nearly conserved in the transition D*0 --> D0 pi0. The transitions D*0 --> D0 pi0 and X --> D0 D0-bar pi0 are described explicitly in XEFT. The effects of the decay D*0 --> D0 gamma and of short-distance decay modes of the X(3872), such as J/psi --> pi+ pi-, can be taken into account by using complex on-shell renormalization schemes for the D*0 propagator and for the D*0 D0-bar propagator in which the positions of their complex poles are specified. Galilean-invariant XEFT is used to calculate the D*0 D0-bar scattering length to next-to-leading order. Galilean invariance ensures the cancellation of ultraviolet divergences without the need for truncating an expansion in powers of the ratio of the pion and charm meson masses.
Comments:
31 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1503.04791 [pdf]
PRD(2015)·57 citations

Affiliations

first authorsco-authorsvia INSPIRE