Nuclear Theory·nucl-th

Tuesday·July 28, 2015

10 papers—4 primary·6 cross-listed

01
[Submitted on 24 Jul 2015]
Short-range correlations in the deuteron: chiral effective field theory, meson-exchange, and phenomenology
Francesca Sammarruca🇺🇸
We study high-momentum distributions and short-range correlation probabilities in the deuteron with a variety of modern potentials based on chiral effective field theory up to fifth order in the chiral expansion. We also consider some conventional (meson-exchange and phenomenological) interactions. We examine our predictions in the context of short-range correlation probabilities as extracted from analyses of inclusive electron scattering data and discuss whether modern interac- tions can be reconciled with the latter.
Comments:
11 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1507.07043 [pdf]
PRC(2015)·10 citations
02
[Submitted on 26 Jul 2015]
Halo effective field theory constrains the solar Beryllium-7 + proton -> Boron-8 + photon rate
Xilin Zhang · Kenneth M. Nollett · D. R. Phillips
We report an improved low-energy extrapolation of the cross section for the process Beryllium-7+proton -> Boron-8+photon, which determines the Boron-8 neutrino flux from the Sun. Our extrapolant is derived from Halo Effective Field Theory (EFT) at next-to-leading order. We apply Bayesian methods to determine the EFT parameters and the low-energy S-factor, using measured cross sections and scattering lengths as inputs. Asymptotic normalization coefficients of Boron-8 are tightly constrained by existing radiative capture data, and contributions to the cross section beyond external direct capture are detected in the data at E < 0.5 MeV. Most importantly, the S-factor at zero energy is constrained to be S(0)= 21.3 + - 0.7 eV b, which is an uncertainty smaller by a factor of two than previously recommended. That recommendation was based on the full range for S(0) obtained among a discrete set of models judged to be reasonable. In contrast, Halo EFT subsumes all models into a controlled low-energy approximant, where they are characterized by nine parameters at next-to-leading order. These are fit to data, and marginalized over via Monte Carlo integration to produce the improved prediction for S(E).
Comments:
7 pages, 3 figures, 2 tables, and 1 supplemental material
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1507.07239 [pdf]
PLB(2015)·64 citations
03
[Submitted on 27 Jul 2015]
Nuclear matter equation of state from a quark-model nucleon-nucleon interaction
K. Fukukawa🇮🇹 · M. Baldo🇮🇹 · G. F. Burgio🇮🇹 · L. Lo Monaco🇮🇹 · H.-J. Schulze🇮🇹
Starting from a realistic constituent quark model for the nucleon-nucleon interaction, we derive the equation of state (EOS) of nuclear matter within the Bethe-Brueckner-Goldstone approach up to three-hole-line level, without need to introduce three-nucleon forces. To estimate the uncertainty of the calculations both the gap and the continuous choices for the single-particle potential are considered and compared. The resultant EOS is compatible with the phenomenological analysis on the saturation point, the incompressibility, the symmetry energy at low density and its slope at saturation, together with the high-density pressure extracted from flow data on heavy ion collisions. Although the symmetry energy is appreciably larger in the gap choice in the high-density region, the maximum neutron star masses derived from the continuous-choice EOS and the gap-choice EOS are similar and close to two solar masses, which is again compatible with recent observational data. Comparison with other microscopic EOS is presented and discussed.
Comments:
15 pages, 11 figures, 8 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1507.07288 [pdf]
PRC(2015)·29 citations
04
[Submitted on 27 Jul 2015]
Large scale evaluation of beta-decay rates of r-process nuclei with the inclusion of first-forbidden transitions
T. Marketin · L. Huther · G. Martínez-Pinedo
R-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are beta-decay half-lives of neutron rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. We use a fully self-consistent covariant density functional theory (CDFT) framework to provide a table of $β$ -decay half-lives and $β$ -delayed neutron emission probabilities, including first-forbidden transitions. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced, both for even-even, odd-A and odd-odd nuclei, in particular for short-lived nuclei.
Comments:
18 pages, 17 figures, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1507.07442 [pdf]
PRC(2016)·280 citations
05
[Submitted on 25 Jul 2015] (cross-list from hep-ph)
Stellar matter with pseudoscalar condensates
A. A. Andrianov🇷🇺 · V. A. Andrianov🇷🇺 · D. Espriu🇪🇸 · S. S. Kolevatov🇷🇺
In this work we consider how the appearance of gradients of pseudoscalar condensates in dense systems may possibly influence the transport properties of photons in such a medium as well as other thermodynamic characteristics. We adopt the hypothesis that in regions where the pseudoscalar density gradient is large the properties of photons and fermions are governed by the usual lagrangian extended with a Chern-Simons interaction for photons and a constant axial field for fermions. We find that these new pieces in the lagrangian produce non-trivial reflection coefficients both for photons and fermions when entering or leaving a region where the pseudoscalar has a non-zero gradient. A varying pseudoscalar density may also lead to instability of some fermion and boson modes and modify some properties of the Fermi sea. We speculate that some of these modifications could influence the cooling rate of stellar matter (for instance in compact stars) and have other observable consequences. While quantitative results may depend on precise astrophysical details most of the consequences are quite universal and consideration should be given to this possibility.
Comments:
14 pages,6 figures, the version to be published
Subjects:
High Energy Physics — Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1507.07087 [pdf]
EPJC(2016)·4 citations
06
[Submitted on 25 Jul 2015] (cross-list from hep-ph)
Further study of the $N Ω$ dibaryon within constituent quark models
Hongxia Huang🇨🇳 · Jialun Ping🇨🇳 · Fan Wang🇨🇳
Inspired by the discovery of the dibaryon $d^{*}$ and the experimental search of $N Ω$ dibaryon with the STAR data, we study the strange dibaryon $N Ω$ further in the framework of quark delocalization color screening model and chiral quark model. We have shown $N Ω$ is a narrow resonance in $ΛΞ$ D-wave scattering before. However, the $Λ$ - $Ξ$ scattering data analysis is quite complicated. Here we calculate the low-energy $N Ω$ scattering phase shifts, scattering length, effective range and binding energy to provide another approach of STAR data analysis. Our results show there exists an $N Ω$ "bound" state, which can be observed by the $N$ - $Ω$ correlation analysis with RHIC and LHC data, or by the new developed automatic scanning system at J-PARC. Besides, we also find that the hidden color channel-coupling is important for the $N Ω$ system to develop intermediate-range attraction.
Comments:
7 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.07124 [pdf]
PRC(2015)·41 citations
07
[Submitted on 26 Jul 2015] (cross-list from nucl-ex)
Measurement of interaction between antiprotons
STAR Collaboration
One of the primary goals of nuclear physics is to understand the force between nucleons, which is a necessary step for understanding the structure of nuclei and how nuclei interact with each other. Rutherford discovered the atomic nucleus in 1911, and the large body of knowledge about the nuclear force since acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, we have no direct knowledge of the nuclear force between antinucleons. Here, we study antiproton pair correlations among data taken by the STAR experiment at the Relativistic Heavy Ion Collider and show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: namely, the scattering length (f0) and effective range (d0). As direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, our result provides a fundamental ingredient for understanding the structure of more complex antinuclei and their properties.
Comments:
25 pages, 4 figures. Submitted to Nature. Under media embargo
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1507.07158 [pdf]
Nature(2015)·130 citations
08
[Submitted on 26 Jul 2015] (cross-list from astro-ph.HE)
The many faces of strange matter: compact stars, cosmic rays, and dark matter
Renxin Xu (PKU)
The state of cold bulk matter at around nuclear density depends on the fundamental strong interaction between quarks at low-energy scale, so-called non-perturbative quantum chromo-dynamics. Such kind of matter is conjectured to be condensed matter of 3-flavour (u, d and s) quark clusters in this note, being manifested in the form of compact stars, cosmic rays, and even dark matter.
Comments:
3 pages, 1 figure. Proceeding of "Quarks and Compact Stars 2014 at KIAA (Beijing)"
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1507.07172 [pdf]
Acta Astron.Sin.Suppl.(2015)·1 citation
09
[Submitted on 27 Jul 2015] (cross-list from hep-ph)
Testing the $χ_{c 1} p$ composite nature of the $P_{c} (4450)$
Ulf-G. Meißner🇩🇪 · José A. Oller🇪🇸
Making use of a recently proposed formalism, we analyze the composite nature of the $P_{c} (4450)$ resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a $χ_{c 1}$ and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by $J /Ψ p$ . We further argue that this is very similar to the case of the scalar meson $f_{0} (980)$ which is located closely to the $K K ˉ$ threshold and has a suppressed decay into the lighter $π π$ channel.
Comments:
6 pages, 2 tables. One more grant is acknowledged
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1507.07478 [pdf]
PLB(2015)·202 citations
10
[Submitted on 27 Jul 2015] (cross-list from hep-lat)
The QCD phase diagram from analytic continuation
R. Bellwied🇺🇸 · S. Borsanyi🇩🇪 · Z. Fodor🇩🇪 · J. Günther🇩🇪 · S. D. Katz🇭🇺 · C. Ratti🇺🇸 · K. K. Szabo🇩🇪
We present the crossover line between the quark gluon plasma and the hadron gas phases for small real chemical potentials. First we determine the effect of imaginary values of the chemical potential on the transition temperature using lattice QCD simulations. Then we use various formulas to perform an analytic continuation to real values of the baryo-chemical potential. Our data set maintains strangeness neutrality to match the conditions of heavy ion physics. The systematic errors are under control up to $μ_{B} \approx 300$ MeV. For the curvature of the transition line we find that there is an approximate agreement between values from three different observables: the chiral susceptibility, chiral condensate and strange quark susceptibility. The continuum extrapolation is based on $N_{t} =$ 10, 12 and 16 lattices. By combining the analysis for these three observables we find, for the curvature, the value $κ = 0.0149 \pm 0.0021$ .
Comments:
14 pages, 4 figures, revised version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.07510 [pdf]
PLB(2015)·292 citations

Affiliations

first authorsco-authorsvia INSPIRE