PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·March 4, 2016

12 papers—5 primary·7 cross-listed

All12Primary5Cross-lists7
  1. 06

    [Submitted on 28 Feb 2016] (cross-list from gr-qc)

    Spin Precession of Slow Neutrons in Einstein-Cartan Gravity with Torsion, Chameleon and Magnetic Field

    A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹

    We analyse a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn (Phys. Rev. D92, 125004 (2015)) for slow neutrons, coupled to gravitational, chameleon and torsion fields to order 1/m, where m is the neutron mass. In addition to this low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor degrees of freedom. Such anti-Hermitian operators violate CP and T invariance. One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of i) violation of CP and T invariance in the Universe and ii) of baryon asymmetry.

    Comments:
    14 pages, no figures
    Subjects:
    General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1602.08709 [pdf]
    PRD(2016)·12 citations
  2. 07

    [Submitted on 2 Mar 2016] (cross-list from nucl-ex)

    Nucleon Resonance Physics

    Volker D. Burkert🇺🇸

    Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of . In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degrees of freedom underlying the excited states and their dependence on the distance scale probed.

    Comments:
    9 pages. 9 figures, ECT* 2015 Workshop on Nucleon Resonances, October 12-16, 2015, Trento, Italy
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1603.00919 [pdf]
    Few Body Syst.(2016)·17 citations
  3. 08

    [Submitted on 3 Mar 2016] (cross-list from hep-lat)

    Hadron Interactions from lattice QCD

    Sinya Aoki🇯🇵

    We review our strategy to study hadron interactions from lattice QCD using newly proposed potential method. We first explain our strategy in the case of nuclear potentials and its application to nuclear physics. We then discuss the origin of the repulsive core, by adding strange quarks to the system. We also explore a possibility for H-dibaryon to exist in flavor SU(3) limit of lattice QCD. We conclude the paper with an application of our strategy to investigate the maximum mass of neutron stars.

    Comments:
    9 pages, 11 figures, A plenary talk given at "21st International Conference on Few-Body Problems in Physics", May 18-22, 2015, Chicago, USA
    Subjects:
    High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1603.00989 [pdf]
    EPJ Web Conf.(2016)·2 citations
  4. 09

    [Submitted on 3 Mar 2016] (cross-list from hep-lat)

    Axial U(1) symmetry in the chiral symmetric phase of 2-flavor QCD at finite temperature

    Sinya Aok for JLQCD Collaboration🇯🇵

    We discuss the fate of the axial U(1) symmetry in 2-flavor QCD at finite temperature, where the non-singlet chiral symmetry is restored. We first summarize the previous theoretical investigation on the relation between the eigenvalue density of the Dirac operator and the axial U(1) symmetry. We show that the eigenvalue density near the origin behaves as with in the chirally symmetric phase, where is an eigenvalue. This implies that the axial U(1) symmetry is partially restored, so that the low energy symmetry of the theory becomes SU(2) SU(2) Z. Secondly, we report recent numerical investigations on this issue by lattice QCD simulations with lattice chiral fermions such as Overlap or improved domain-wall fermions. Our preliminary results indicate that the eigenvalue density seems to have a gap at the origin just above , the temperature of the chiral symmetry restoration, which implies the axial U(1) symmetry is effectively restored at high temperature. We also point out an importance of the exact lattice chiral symmetry to obtain correct results on this issue.

    Comments:
    10 pages, 5 figures, A talk given at "The 8th International Workshop on Chiral Dynamics, CD2015", 29 June - 03 July, 2015, Pisa, Italy
    Subjects:
    High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1603.00997 [pdf]
    PoS(2016)·5 citations
  5. 10

    [Submitted on 3 Mar 2016] (cross-list from hep-ph)

    Effect of the cross-section uncertainties on an analysis of neutrino oscillations

    Artur M. Ankowski🇺🇸 · Omar Benhar🇺🇸 · Camillo Mariani🇺🇸 · Erica Vagnoni🇮🇹

    We report the results of a study aimed at quantifying the impact on the oscillation analysis of the uncertainties associated with the description of the neutrino-nucleus cross section in the two-particle--two-hole sector. The results of our calculations, based on the kinematic method of energy reconstruction and carried out comparing two data-driven approaches, show that the existing discrepancies in the neutrino cross sections have a sizable effect on the extracted oscillation parameters, particularly in the antineutrino channel.

    Comments:
    7 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1603.01072 [pdf]
    PRD(2016)·29 citations
  6. 11

    [Submitted on 3 Mar 2016] (cross-list from hep-ph)

    and and its partner states

    Yan-Rui Liu🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    Stimulated by the recent observation of the , we study the and its partners under the tetraquark scenario. In the framework of the color-magnetic interaction, we estimate the masses of the partner states of the and discuss their decay pattern, which provide valuable information on the future experimental search of these states.

    Comments:
    7 pages, suggestions and comments are welcome
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1603.01131 [pdf]
    PRD(2016)·64 citations
  7. 12

    [Submitted on 3 Mar 2016] (cross-list from hep-th)

    Thermodynamics, transport and relaxation in non-conformal theories

    Maximilian Attems🇪🇸 · Jorge Casalderrey-Solana🇬🇧 · David Mateos🇪🇸 · Ioannis Papadimitriou🇮🇹 · Daniel Santos-Oliván🇪🇸 · Carlos F. Sopuerta🇪🇸 · Miquel Triana🇪🇸 · Miguel Zilhão🇪🇸

    We study the equilibrium and near-equilibrium properties of a holographic five-dimensional model consisting of Einstein gravity coupled to a scalar field with a non-trivial potential. The dual four-dimensional gauge theory is not conformal and, at zero temperature, exhibits a renormalisation group flow between two different fixed points. We quantify the deviations from conformality both in terms of thermodynamic observables and in terms of the bulk viscosity of the theory. The ratio of bulk over shear viscosity violates Buchel's bound. We study relaxation of small-amplitude, homogeneous perturbations by computing the quasi-normal modes of the system at zero spatial momentum. In this approximation we identify two different relaxation channels. At high temperatures, the different pressures first become approximately equal to one another, and subsequently this average pressure evolves towards the equilibrium value dictated by the equation of state. At low temperatures, the average pressure first evolves towards the equilibrium pressure, and only later the different pressures become approximately equal to one another.

    Comments:
    22 pages, 29 figures; published version
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1603.01254 [pdf]
    JHEP(2016)·95 citations

Affiliations

first authorsco-authorsvia INSPIRE