Nuclear Theory·nucl-th

Friday·August 21, 2015

12 papers—8 primary·4 cross-listed

01
[Submitted on 19 Aug 2015]
Establishing a theory for deuteron induced surrogate reactions
Gregory Potel Aguilar · Filomena M. Nunes · Ian J. Thompson
The goal of this work is to establish on firm grounds a theory for deuteron induced neutron capture reactions. This includes formulating elastic and inelastic breakup in a consistent manner. We describe this process both in post and prior form distorted wave Born approximation, and we apply our method to the 53Nb(d,p)X at Ed =15 MeV and 25 MeV, obtaining a good description of the data. We look at the various partial wave contributions, as well as elastic versus inelastic contributions. We also connect our formulation with transfer to neutron bound states.
Comments:
11 pages, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.04822 [pdf]
PRC(2015)·95 citations
02
[Submitted on 20 Aug 2015]
The Relativistic Three-Body Bound State in Three-Dimensions
M. R. Hadizadeh · Ch. Elster · W. N. Polyzou
Studying of the relativistic three-body bound state in a three-dimensional (3D) approach is a necessary first step in a process to eventually perform scattering calculations at GeV energies, where partial-wave expansions are not useful. To this aim we recently studied relativistic effects in the binding energy and for the first time, obtained the relativistic 3B wave function \cite{Hadizadeh_PRC90}. The relativistic Faddeev integral equations for the bound state are formulated in terms of momentum vectors, and relativistic invariance is incorporated within the framework of Poincaré invariant quantum mechanics.
Comments:
Contribution to the 21st International Conference on Few-Body Problems in Physics, Chicago, Illinois, USA
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.04840 [pdf]
EPJ Web Conf.(2016)·7 citations
03
[Submitted on 20 Aug 2015]
Hyperon Puzzle, Hadron-Quark Crossover and Massive Neutron Stars
Kota Masuda🇯🇵 · Tetsuo Hatsuda🇯🇵 · Tatsuyuki Takatsuka🇯🇵
Bulk properties of cold and hot neutron stars (NSs) are studied on the basis of the hadron-quark crossover picture where a smooth transition from the hadronic phase to the quark phase takes place at finite baryon density. By using a phenomenological equation of state (EOS) "CRover" which interpolates the two phases at around 3 times the nuclear matter density, it is found that the cold NSs with the gravitational mass larger than 2-solarmass can be sustained. This is in sharp contrast to the case of the first-order hadron-quark transition. The radii of the cold NSs with the CRover EOS are in the narrow range which is insensitive to the NS masses. Due to the stiffening of the EOS induced by the hadron-quark crossover, the central density of the NSs is at most 4 times the nuclear matter density and the hyperon-mixing barely occurs inside the NS core. This constitutes a solution of the long-standing hyperon puzzle. The effect of color superconductivity (CSC) on the NS structures is also examined with the hadron-quark crossover. For the typical strength of the diquark attraction, a slight softening of the EOS due to two-flavor CSC (2SC) takes place and the maximum mass is reduced by about 0.2-solarmass. The CRover EOS is generalized to the supernova matter at finite temperature to describe the hot NSs at birth. The hadron-quark crossover is found to decrease the central temperature of the hot NSs under isentropic condition. The gravitational energy release and the spin-up rate during the contraction from the hot NS to the cold NS are also estimated.
Comments:
15 pages, 13 figures; prepared for the 2015 EPJA Topical Issue on "Exotic Matter in Neutron Stars"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1508.04861 [pdf]
EPJA(2016)·66 citations
04
[Submitted on 20 Aug 2015]
Weak decay of Lambda_c^+ for the study of Lambda(1405) and Lambda(1670)
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵 · Eulogio Oset🇪🇸
We study the Lambda_c decay process to pi^+ and the meson-baryon final state for the analysis of Lambda resonances. Considering the Cabibbo-Kobayashi-Maskawa matrix, color suppression, diquark correlation and the kinematical condition, we show that the final meson-baryon state should be in a pure I=0 combination, when the meson-baryon invariant mass is small. Because the I=1 contamination usually makes it difficult to analyze Lambda resonances directly from experiments, the Lambda_c decay is an ideal process to study Lambda resonances. Calculating the final state interaction by chiral unitary approaches, we find that the piSigma invariant mass distributions have the same peak structure in the all charge combination of the piSigma states related to the higher pole of the two poles of the Lambda(1405). Furthermore, we obtain a clear the Lambda(1670) peak structure in the KbarN and etaLambda spectra.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1508.04882 [pdf]
PRC(2015)·72 citations
05
[Submitted on 20 Aug 2015]
Neutron star structure from QCD
Eduardo S. Fraga🇧🇷 · Aleksi Kurkela🇨🇭 · Aleksi Vuorinen🇫🇮
In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.
Comments:
Invited contribution to the EPJA Topical Issue "Exotic Matter in Neutron Stars"; 10 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1508.05019 [pdf]
EPJA(2016)·58 citations
06
[Submitted on 20 Aug 2015]
Exploring sd-shell nuclei from two- and three-nucleon interactions with realistic saturation properties
J. Simonis · K. Hebeler · J.D. Holt · J. Menendez · A. Schwenk
We study ground- and excited-state properties of all sd-shell nuclei with neutron and proton numbers 8 <= N,Z <= 20, based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties of nuclear matter. We focus on estimating the theoretical uncertainties due to variation of the resolution scale, the low-energy couplings, as well as from the many-body method. The experimental two-neutron and two-proton separation energies are reasonably well reproduced, with an uncertainty range of about 5 MeV. The first excited 2+ energies also show overall agreement, with a more narrow uncertainty range of about 500 keV. In most cases, this range is dominated by the uncertainties in the Hamiltonian.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1508.05040 [pdf]
PRC(2016)·114 citations
07
[Submitted on 20 Aug 2015]
Towards a Faddeev-AGS description of $(d, p)$ reactions with heavy nuclei: Regularizing integrals with Coulomb functions
The TORUS Collaboration: V. Eremenko · L. Hlophe · Ch. Elster · F.M. Nunes · I.J. Thompson · G. Arbanas · J.E. Escher
The repulsive Coulomb force poses severe challenges when describing $(d, p)$ reactions for highly charged nuclei as a three-body problem. Casting Faddeev-AGS equations in a Coulomb basis avoids introducing screening of the Coulomb force. However, momentum space partial-wave $t$ -matrix elements need to be evaluated in this basis. When those $t$ -matrices are separable, the evaluation requires the folding of a form factor, depending on one momentum variable, with a momentum space partial-wave Coulomb function, which has a singular behavior at the external momentum $q$ . We developed an improved regularization scheme to calculate Coulomb distorted form factors as the integral over the Coulomb function and complex nuclear form factors.
Comments:
Submitted proceedings of the 21st International Conference on Few-Body Problems in Physics. 4 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.05061 [pdf]
EPJ Web Conf.(2016)·1 citation
08
[Submitted on 20 Aug 2015]
Effective Theory of 3H and 3He
Sebastian König🇺🇸 · Harald W. Grießhammer🇺🇸 · H.-W. Hammer🇩🇪 · U. van Kolck🇫🇷
We present a new perturbative expansion for pionless effective field theory with Coulomb interactions in which at leading order the spin-singlet nucleon-nucleon channels are taken in the unitarity limit. Presenting results up to next-to-leading order for the Phillips line and the neutron-deuteron doublet-channel phase shift, we find that a perturbative expansion in the inverse 1S0 scattering lengths converges rapidly. Using a new systematic treatment of the proton-proton sector that isolates the divergence due to one-photon exchange, we renormalize the corresponding contribution to the 3H-3He binding energy splitting and demonstrate that the Coulomb force in pionless EFT is a completely perturbative effect in the trinucleon bound-state regime. In our new expansion, the leading order is exactly isospin-symmetric. At next-to-leading order, we include isospin breaking via the Coulomb force and two-body scattering lengths, and find for the energy splitting (E_B(3He)-E_B(3H))^NLO = (-0.86 +/- 0.17) MeV.
Comments:
37 pages, 14 figures, published version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.05085 [pdf]
J.Phys.G(2016)·74 citations
09
[Submitted on 18 Aug 2015] (cross-list from cond-mat.mes-hall)
Generalized Landau level representation: Effect of static screening in the quantum Hall effect in graphene
Igor A. Shovkovy🇺🇸 · Lifang Xia🇺🇸
By making use of the generalized Landau level representation (GLLR) for the quasiparticle propagator, we study the effect of screening on the properties of the quantum Hall states with integer filling factors in graphene. The analysis is performed in the low-energy Dirac model in the mean-field approximation, in which the long-range Coulomb interaction is modified by the one-loop static screening effects in the presence of a background magnetic field. By utilizing a rather general ansatz for the propagator, in which all dynamical parameters are running functions of the Landau level index $n$ , we derive a self-consistent set of the Schwinger-Dyson (gap) equations and solve them numerically. The explicit solutions demonstrate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken $U (4)$ flavor symmetry. The temperature dependence of the energy gaps is also studied. The corresponding results mimic well the temperature dependence of the activation energies measured in experiment. It is also argued that, in principle, the Landau level running of the quasiparticle dynamical parameters could be measured via optical studies of the integer quantum Hall states.
Comments:
18 pages, 6 multi-panel figures; v2: published version with extended discussions and several new references
Subjects:
Mesoscale and Nanoscale Physics (cond-mat.mes-hall); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1508.04471 [pdf]
PRB(2016)·2 citations
10
[Submitted on 20 Aug 2015] (cross-list from hep-ph)
The Effects of Superhigh Magnetic Fields on Equations of States of Neutron Stars
Z.F.Gao🇨🇳 · N.Wang🇨🇳 · Y.Xu · H.Shan🇨🇳 · X.D.Li🇨🇳
By introducing Dirac ?-function in superhigh magnetic field, we deduce a general formula for pressure of degenerate and relativistic electrons, Pe, which is suitable for superhigh magnetic fields, discuss the quantization of Landau levels of electrons, and consider the quantum electrodynamic(QED) effects on the equations of states (EOSs) for different matter systems. The main conclusions are as follows: the stronger the magnetic field strength, the higher the electron pressure becomes; compared with a common radio pulsar, a magnetar could be a more compact oblate spheroid-like deformed neutron star due to the anisotropic total pressure; and an increase in the maximum mass of a magnetar is expected because of the positive contribution of the magnetic field energy to the EOS of the star. Since this is an original work in which some uncertainties could exist, to further modify and perfect our theory model should be considered in our future studies.
Comments:
arXiv admin note: substantial text overlap with arXiv:1312.1442
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1508.04860 [pdf]
Astron.Nachr.(2015)·18 citations
11
[Submitted on 20 Aug 2015] (cross-list from nucl-ex)
Short-range correlations and their implications for isospin-dependent modification of nuclear quark distributions
John Arrington🇺🇸
The past decade has provided a much clearer picture of the structure of high-momentum components in nucleons, associated with hard, short-distance interactions between pairs of nucleons. Recent Jefferson Lab data on light nuclei suggest a connection between these so-called 'short-range correlations' and the modification of the quark structure of nucleons in the nuclear environment. In light of this discovery that the detailed nuclear structure is important in describing the nuclear quark distributions, we examine the potential impact of the isospin-dependent structure of nuclei to see at what level this might yield flavor-dependent effects in nuclear quark distributions.
Comments:
10 pages, 2 figures, proceedings from the 21st international conference on few-body physics
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1508.05042 [pdf]
EPJ Web Conf.(2016)·12 citations
12
[Submitted on 20 Aug 2015] (cross-list from hep-ph)
Correct Definition of the Gluon Fragmentation Function at High Energy Colliders
Gouranga C. Nayak
Since the definition of the gluon to hadrons fragmentation amplitude $< H, X ∣ g >$ involves gluon field $Q^{μ a} (x)$ corresponding to single gluon incoming state $∣ g >$ , the present definition of the gluon fragmentation function at high energy colliders [which involves non-abelian field tensor $F^{μν a} (x) = \partial^{μ} Q^{ν a} (x) - \partial^{ν} Q^{μ a} (x) + g f^{ab c} Q^{μ b} (x) Q^{ν c} (x)$ instead of $Q^{μ a} (x)$ in the initial state] is not consistent with the single gluon incoming state $∣ g >$ . In this paper we derive the correct definition of the gluon fragmentation function at high energy colliders from first principles which is obtained from the single gluon incoming state $∣ g >$ and is gauge invariant and is consistent with the factorization theorem in QCD.
Comments:
13 pages latex. arXiv admin note: substantial text overlap with arXiv:1506.02651, arXiv:1506.02593, arXiv:1508.01194
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1508.05078 [pdf]
2 citations

Affiliations

first authorsco-authorsvia INSPIRE