Nuclear Theory·nucl-th

Monday·April 10, 2017

9 papers—7 primary·2 cross-listed

01
Inclusive neutrino scattering off deuteron at low energies in chiral effective field theory
A. Baroni🇺🇸 · R. Schiavilla🇺🇸
Cross sections for inclusive neutrino scattering off deuteron induced by neutral and charge-changing weak currents are calculated from threshold up to 150 MeV energies in a chiral effective field theory including high orders in the power counting. Contributions beyond leading order (LO) in the weak current are found to be small, and increase the cross sections obtained with the LO transition operators by a couple of percent over the whole energy range (0--150) MeV. The cutoff dependence is negligible, and the predicted cross sections are within $\sim 2$ \% of, albeit consistently larger than, corresponding predictions obtained in conventional meson-exchange frameworks.
nucl-thPRC(2017)·9 citations
02
$D D ˉ^{*}$ and $π ψ$ interactions in a unitary coupled-channel approximation
Bao-Xi Sun🇨🇳 · Da-Ming Wan🇨🇳 · Guang-Yi Tang🇨🇳 · Fang-Yong Dong🇨🇳
The $D D ˉ^{*}$ interaction via a $π ψ$ intermediate state is studied carefully in the isospin $I = 1$ sector. By solving the Bethe-Salpeter equation in the unitary coupled-channel approximation, we obtain the S-wave amplitude as a function of the total energy of the system in the center of mass frame. A resonance state is generated dynamically in the 3900MeV region, which might correspond to the $Z c (3900)$ particle. Moreover, the loop function of a vector meson and a pseudoscalar meson is deduced explicitly in the dimensional regularization scheme and the contribution of the longitudinal part of the vector meson propagator is taken into account. The initial and final polarization vectors in the vertex of the vector meson and the pseudoscalar meson are eliminated when the Bethe-Salpeter equation is solved, and it is certified that the amplitude is still unitary in the calculation.
nucl-th3 citations
03
Vorticity in the QGP liquid and $Λ$ polarization at the RHIC Beam Energy Scan
Iu. Karpenko🇮🇹 · F. Becattini🇮🇹
Polarization of $Λ$ hyperons and their antiparticles is calculated in a 3+1 dimensional viscous hydrodynamic model with initial state from UrQMD hadron/string cascade. We find that, along with recent results from STAR, the mean polarization at fixed centrality decreases as a function of collision energy from 1.5% at $s_{NN} = 7.7$ GeV to 0.2% at $s_{NN} = 200$ GeV. We explore the effects which lead to such collision energy dependence, feed-down corrections and a difference between $Λ$ and $Λ ˉ$ .
nucl-thhep-phnucl-exNPA(2017)·20 citations
04
Examining possible neutron-halo nuclei heaver than $^{37}$ Mg
Ikuko Hamamoto
The even-Z odd-N neutron-halo nuclei, which are the possible lightest neutron-halo nuclei heavier than $^{37}$ Mg, are explored by studying the shell-structure unique in weakly-bound neutrons for spherical or deformed shape. It is pointed out that due to the narrowed N=50 spherical energy-gap and a few resulting close-lying neutron one-particle levels, 1g $_{9/2}$ , 3s $_{1/2}$ , and 2d $_{5/2}$ , for spherical shape, nuclei with some weakly-bound neutrons filling in those levels may be deformed and have a good chance to show deformed s-wave halo. Promising candidates are $_{24}^{71}$ Cr $_{47}$ , $_{24}^{73}$ Cr $_{49}$ , $_{24}^{75}$ Cr $_{51}$ and $_{26}^{77}$ Fe $_{51}$ in the case that those nuclei lie inside the neutron drip-line. An interesting possibility of the deformed p-wave or s-wave halo is suggested also for the nucleus $_{18}^{53}$ Ar $_{35}$ .
nucl-thPRC(2017)·17 citations
05
Effects of pairing correlations on the neutron skin thickness and the symmetry energy
Soonchul Choi🇰🇷 · Ying Zhang · Myung-Ki Cheoun🇰🇷 · Youngshin Kwon🇰🇷 · Kyungsik Kim🇰🇷 · Hungchong Kim🇰🇷
We investigated effects of pairing correlations on the neutron skin thickness and the symmetry energy of finite nuclei. In this calculation we used Hartree-Fock-Bogoliubov (HFB) method with Skyrme forces and effective pairing interactions. The results have been compared with available experimental data, Hartree-Fock (HF) results as well as the predictions by droplet model (DM). Finally, our discussion was extended to study of the pairing interaction in nuclear matter. Roles of isospin T = 0 pairing in the nuclear matter were also discussed.
nucl-thPRC(2017)·6 citations
06
Kinetic energy in the collective quadrupole Hamiltonian from the experimental data
R.V. Jolos · E.A. Kolganova
Dependence of the kinetic energy term of the collective nuclear Hamiltonian on collective momentum is considered. It is shown that the fourth order in collective momentum term of the collective quadrupole Hamiltonian generates a sizable effect on the excitation energies and the matrix elements of the quadrupole moment operator. It is demonstrated that the results of calculation are sensitive to the values of some matrix elements of the quadrupole moment. It stresses the importance for a concrete nucleus to have the experimental data for the reduced matrix elements of the quadrupole moment operator taken between all low lying states with the angular momenta not exceeding 4.
nucl-thPLB(2017)·0 citations
07
Transition from vibrational to rotational characters in low-lying states of hypernuclei
H. Mei🇯🇵 · K. Hagino🇯🇵 · J. M. Yao🇺🇸 · T. Motoba🇯🇵
In order to clarify the nature of hypernuclear low-lying states, we carry out a comprehensive study for the structure of $_{Λ}^{144 - 154}$ Sm-hypernuclei, which exhibit a transition from vibrational to rotational characters as the neutron number increases. To this end, we employ a microscopic particle-core coupling scheme based on a covariant density functional theory. We find that the positive-parity ground-state band in the hypernuclei shares a similar structure to that of the corresponding core nucleus. That is, regardless of whether the core nucleus is spherical or deformed, each hypernuclear state is dominated by the single configuration of the $Λ$ particle in the $s_{1/2}$ state ( $Λ s_{1/2}$ ) coupled to one core state of the ground band. In contrast, the low-lying negative-parity states mainly consist of $Λ p_{1/2}$ and $Λ p_{3/2}$ configurations coupled to plural nuclear core states. We show that, while the mixing amplitude between these configurations is negligibly small in spherical and weakly-deformed nuclei, it strongly increases as the core nucleus undergoes a transition to a well-deformed shape, being consistent with the Nilsson wave functions. We demonstrate that the structure of these negative-parity states with spin $I$ can be well understood based on the $L S$ coupling scheme, with the total orbital angular momentum of $L = [I \otimes 1]$ and the spin angular momentum of $S = 1/2$ .
nucl-thnucl-exPRC(2017)·7 citations
08
Universal few-body physics and cluster formation
Chris H. Greene · P. Giannakeas · J. Perez-Rios
A recent rejuvenation of experimental and theoretical interest in the physics of few- body systems has provided deep, fundamental insights into a broad range of problems. Few-body physics is a cross-cutting discipline not restricted to conventional subject ar- eas such as nuclear physics or atomic or molecular physics. To a large degree, the recent explosion of interest in this subject has been sparked by dramatic enhancements of experimental capabilities in ultracold atomic systems over the past decade, which now permit atoms and molecules to be explored deep in the quantum mechanical limit with controllable two-body interactions. This control, typically enabled by magnetic or electromagnetically-dressed Fano-Feshbach resonances, allows in particular access to the range of universal few-body physics, where two-body scattering lengths far exceed all other length scales in the problem. The Efimov effect, where 3 particles experienc- ing short-range interactions can counterintuitively exhibit an infinite number of bound or quasi-bound energy levels, is the most famous example of universality. Tremendous progress in the field of universal Efimov physics has taken off, driven particularly by a combination of experimental and theoretical studies in the past decade, and prior to the first observation in 2006, by an extensive set of theoretical studies dating back to 1970. Because experimental observations of Efimov physics have usually relied on resonances or interference phenomena in three-body recombination, this connects naturally with the processes of molecule formation in a low temperature gas of atoms or nucleons, and more generally with N-body recombination processes. Some other topics not closely related to the Efimov effect are also reviewed in this article, including ...
↳ cond-mat.quant-gasnucl-thphysics.atm-clusphysics.atom-phRMP(2017)·125 citations
09
Improved Determination of the $^{235} U$ and $^{239} Pu$ Reactor Antineutrino Cross Sections per Fission
Carlo Giunti🇮🇹
We present the results of a combined fit of the reactor antineutrino rates and the Daya Bay measurement of $σ_{f, 235}$ and $σ_{f, 239}$ . The combined fit leads to a better determination of the two cross sections per fission: $σ_{f, 235} = 6.29 \pm 0.08$ and $σ_{f, 239} = 4.24 \pm 0.21$ in units of $1 0^{- 43} cm^{2} / fission$ , with respective uncertainties of about $1.2%$ and $4.9%$ . Since the respective deviations from the theoretical cross sections per fission are $2.5 σ$ and $0.7 σ$ , we conclude that, if the reactor antineutrino anomaly is not due to active-sterile neutrino oscillations, it is likely that it can be solved with a revaluation of the $^{235} U$ reactor antineutrino flux. However, the $^{238} U$ , $^{239} Pu$ , and $^{241} Pu$ fluxes, which have larger uncertainties, could also be significantly different from the theoretical predictions.
↳ hep-phhep-exnucl-exnucl-thPRD(2017)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE