Nuclear Theory·nucl-th

Wednesday·January 28, 2015

9 papers—5 primary·4 cross-listed

01
[Submitted on 26 Jan 2015]
Hadron Physics and QCD: Just the Basic Facts
Craig D. Roberts🇺🇸
With discovery of the Higgs boson, the Standard Model of Particle Physics became complete. Its formulation is a remarkable story; and the process of verification is continuing, with the most important chapter being the least well understood. Quantum Chromodynamics (QCD) is that part of the Standard Model which is supposed to describe all of nuclear physics and yet, almost fifty years after the discovery of quarks, we are only just beginning to understand how QCD moulds the basic bricks for nuclei: pious, neutrons, protons. QCD is characterized by two emergent phenomena: confinement and dynamical chiral symmetry breaking (DCSB), whose implications are extraordinary. This contribution describes how DCSB, not the Higgs boson, generates more than 98% of the visible mass in the Universe, explains why confinement guarantees that condensates, those quantities that were commonly viewed as constant mass-scales that fill all spacetime, are instead wholly contained within hadrons, and elucidates a range of observable consequences of confinement and DCSB whose measurement is the focus of a vast international experimental programme.
Comments:
15 pages, 7 figures. Contribution to the Proceedings of the 37th Brazilian Workshop on Nuclear Physics, Maresias, SP, Brazil
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1501.06581 [pdf]
J.Phys.Conf.Ser.(2015)·25 citations
02
[Submitted on 27 Jan 2015]
Extended-soft-core Baryon-Baryon Model Esc08 II. Hyperon-Nucleon Interactions
M.M. Nagels🇳🇱 · Th.A. Rijken🇯🇵 · Y. Yamamoto🇯🇵
The YN results are presented from a new version of the Extended-soft-core (ESC) potential model for Baryon-baryon (BB) scattering. The potentials consist of local- and non-local-potentials due to (i) One-boson-exchange (OBE), (ii) Pomeron and Odderon exchanges, (iii) Two pseudoscalar-exchange (PS-PS), and (iv) Meson-Pair-exchange (MPE). The OBE- and MPE-vertices are regulated by gaussian form factors, producing moderate size potentials in the origin. In addition to the mentioned ingredients of the ESC-model, also the possible short range repulsion due to the quark Pauli-principle in the BB-channels is included in the analysis. The NN, YN, and the S=-2 YY scattering is treated in a unified way using flavor SU(3) symmetry. With the ESC08-model a simultaneous fit is performed for the combined NN and YN data, using single sets of parameters. The achievement is a fit with (i) $χ^{2} / N N_{d a t a} = 1.081$ , and (ii) $χ^{2} / Y N_{d a t a} = 1.08$ .
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1501.06636 [pdf]
PRC(2019)·114 citations
03
[Submitted on 27 Jan 2015]
Entanglement entropy and Schmidt number as measures of delocalization of $α$ clusters in one-dimensional nuclear systems
Yoshiko Kanada-En'yo🇯🇵
We calculated the von Neumann entanglement entropy and the Schmidt number of one dimentional (1D) cluster states and showed that these are useful measures to estimate entanglement caused by delocalization of clusters. We analyze system size dependence of these entanglement measures in the linear-chain $n α$ states given by Tohsaki-Horiuchi-Schuck-Röpke wave functions for 1D cluster gas states. We show that the Schmidt number is an almost equivalent measures to the von Neumann entanglement entropy when the delocalization of clusters occurs in the entire system but it shows different behaviors in a partially delocalized state containing localized clusters and delocalized ones. It means that the Rényi-2 entanglement entropy, which relates to the Schmidt number, is found to be almost equivalent to the von Neumann entanglement entropy for the full delocalized cluster system but it is less sensitive to the partially delocalized cluster system than the von Neumann entanglement entropy. We also propose a new entanglement measure which has a generalized form of the Schmidt number. Sensitivity of these measures of entanglement to the delocalization of clusters in low-density regions was discussed.
Comments:
15 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Quantum Physics (quant-ph)
arXiv:
1501.06639 [pdf]
PTEP(2015)·10 citations
04
[Submitted on 27 Jan 2015]
Anti-cluster Decay and Anti-alpha Decay of Antimatter nuclei
D. N. Poenaru🇷🇴 · R. A. Gherghescu🇷🇴 · W. Greiner🇩🇪
A broad extension of periodic system into the sector of antimatter could be possible sometimes in a remote future. We expect that anti-alpha spontaneous emission from an antimatter nucleus will have the same Q-value and half-life as alpha emission from the corresponding mirror nucleus. This is the consequence of the invariance of binding energy as well as of the surface and Coulomb energy when passing from matter to antimatter nuclei with the the same mass number and the same atomic number. The Q-values and half-lives of all measured up to now 27 cluster radioactivities are given together with Q-values and half-lives of the most important competitor --- $α$ decay. The lightest anti-alpha emitter, $^{8} B e ˉ$ , will have a very short half-life of about $81.9 \cdot 1 0^{- 18}$ s.
Comments:
11 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1501.06792 [pdf]
1 citation
05
[Submitted on 27 Jan 2015]
Nuclear fusion as a probe for octupole deformation in $^{224}$ Ra
Raj Kumar · J. A. Lay · A. Vitturi
$Background$ : Nuclear fusion has been shown to be a perfect probe to study the different nuclear shapes. However, the possibility of testing octupole deformation of a nucleus with this tool has not been fully explored yet. The presence of a stactic octupole deformation in nuclei will enhanced a possible permanent electric dipole moment, leading to a possible demonstration of parity violation. $Purpose$ : To check whether static octupole deformation or octupole vibration in fusion give qualitatively different results so that both situations can be experimentally disentangled. $Method$ : Fusion cross sections are computed in the Coupled-Channels formalism making use of the Ingoing-Wave Boundary Conditions (IWBC) for the systems $^{16}$ O+ $^{144}$ Ba and $^{16}$ O+ $^{224}$ Ra. $Results$ : Barrier distributions of the two considered schemes show different patterns. For the $^{224}$ Ra case, the octupole deformation parameter is large enough to create a sizeable difference. $Conclusions$ : The measurement of barrier distributions can be an excellent probe to clarify the presence of octupole deformation.
Comments:
Important changes from previous version, 6 pages, 5 figures, 2 tables, submitted to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1501.06801 [pdf]
PRC(2015)·6 citations
06
[Submitted on 26 Jan 2015] (cross-list from hep-ph)
Gluon effects on the equation of state of color superconducting strange stars
E. J. Ferrer🇺🇸 · V. de la Incera🇺🇸 · L. Paulucci🇧🇷
Compact astrophysical objects are a window for the study of strongly interacting nuclear matter given the conditions in their interiors, which are not reproduced in a laboratory environment. Much has been debated about their composition with possibilities ranging from a simple mixture of mostly protons and neutrons to deconfined quark matter. Recent observations on the mass of two pulsars, PSR J1614-2230 and PSR J0348+0432, have posed a great restriction on their composition, since the equation of state must be hard enough to support masses of about at least two solar masses. The onset of quarks tends to soften the equation of state, but it can get substantially stiffer since in the high-dense medium a repulsive vector interaction channel is opened. Nevertheless, we show that once gluon effects are considered, the equation of state of quark matter in the color-flavor-locked phase of color superconductivity becomes softer decreasing the maximum stellar mass that can be reached when not considering their influence. This may indicate that stars made entirely of color superconducting matter can only be favored to describe compact stars if the repulsive vector constant is high enough.
Comments:
11 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1501.06597 [pdf]
PRD(2015)·19 citations
07
[Submitted on 26 Jan 2015] (cross-list from hep-ph)
(In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium
E. J. Ferrer🇺🇸 · V de la Incera🇺🇸 · D. Manreza Paret🇨🇺 · A. Perez Martinez🇨🇺 · A. Sanchez🇲🇽
We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.
Comments:
More detailed figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1501.06616 [pdf]
PRD(2015)·89 citations
08
[Submitted on 27 Jan 2015] (cross-list from hep-ph)
Power counting for three-body decays of a near-threshold state
Mohammad H. Alhakami🇬🇧 · Michael C. Birse (University of Manchester)🇬🇧
We propose a new power counting for the effective field theory describing a near-threshold state with unstable constituents, such as the X(3872) meson. In this counting, the momenta of the heavy particles, the pion mass and the excitation energy of the unstable constituent -- the D* in the case of the X -- are treated as small scales, of order Q. The difference, delta, between the excitation energy of the D* and the pion mass is smaller than either by a factor ~20. We therefore assign delta an order Q^2 in our counting. This provides a consistent framework for a double expansion in both delta/m_pi and the ratio of m_pi to the high-energy scales in this system. It ensures that amplitudes have the correct behaviour at the three-body threshold. It allows us to derive, within an effective theory, various results which have previously been obtained using physically-motivated approximations.
Comments:
5 pages, 1 figure; more discussion of pion exchange added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1501.06750 [pdf]
PRD(2015)·14 citations
09
[Submitted on 27 Jan 2015] (cross-list from nucl-ex)
2014 Update of the Discoveries of Nuclides
M. Thoennessen
The 2014 update of the discovery of nuclide project is presented. Only six new nuclides were observed for the first time in 2014 while the assignments of seventeen other nuclides were revised. In addition, for another fourteen nuclides the laboratories where they were discovered were reassigned.
Comments:
Accepted for publication in IJMPE
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1501.06761 [pdf]
IJMPE(2015)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE