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Nuclear Theory·nucl-th

Wednesday·February 9, 2022

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 04

    [Submitted on 8 Feb 2022] (cross-list from quant-ph)

    Physical symmetries and gauge choices in the Landau problem

    Masashi Wakamatsu🇯🇵 · Akihisa Hayashi🇯🇵

    Due to a special nature of the Landau problem, in which the magnetic field is uniformly spreading over the whole two-dimensional plane, there necessarily exist three conserved quantities, i.e. two conserved momenta and one conserved orbital angular momentum for the electron, independently of the choice of the gauge potential. Accordingly, the quantum eigen-functions of the Landau problem can be obtained by diagonalizing the Landau Hamiltonian together with one of the above three conserved operators with the result that the quantum mechanical eigen-functions of the Landau problem can be written down for arbitrary gauge potential. The purpose of the present paper is to clarify the meaning of gauge choice in the Landau problem based on this gauge-potential-independent formulation, with a particular intention of unraveling the physical significance of the concept of gauge-invariant-extension of the canonical orbital angular momentum advocated in recent literature on the nucleon spin decomposition problem. At the end, our analysis is shown to disclose a physically vacuous side face of the gauge symmetry.

    Comments:
    version to appear in The European Physical Journal A
    Subjects:
    Quantum Physics (quant-ph); High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
    arXiv:
    2202.03592 [pdf]
    EPJA(2022)·14 citations
  2. 05

    [Submitted on 8 Feb 2022] (cross-list from hep-lat)

    Generalised Parton Distributions from Lattice Feynman-Hellmann Techniques

    Alec Hannaford-Gunn🇦🇺 · Kadir Utku Can🇬🇧 · Roger Horsley🇩🇪 · Holder Perlt🇬🇧 · Paul Rakow🇩🇪 · Gerrit Schierholz🇩🇪 · Hinnerk Stüben🇦🇺 · Ross Young🇦🇺 · James Zanotti🇦🇺

    We report on the use of Feynman-Hellmann techniques to calculate the off-forward Compton amplitude (OFCA) in lattice QCD. At leading-twist, the Euclidean OFCA is parameterised by the Mellin moments of generalised parton distributions (GPDs). Hence we extract GPD moments for two values of the soft momentum transfer, and zero-skewness kinematics at an unphysical pion mass of . This includes the first determination of the moments.

    Comments:
    9 pages, 3 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2202.03662 [pdf]
    PoS(2022)·4 citations
  3. 06

    [Submitted on 8 Feb 2022] (cross-list from hep-ph)

    Spin waves in spin hydrodynamics

    Victor E. Ambrus🇩🇪 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱

    The propagation properties of spin degrees of freedom are analyzed in the framework of relativistic hydrodynamics with spin based on the de Groot--van Leeuwen--van Weert definitions of the energy-momentum and spin tensors. We derive the analytical expression for the spin wave velocity for arbitrary statistics and show that it goes to half the speed of light in the ultra-relativistic limit. We find that only the transverse degrees of freedom propagate, analogously to electromagnetic waves. Finally, we consider the effect of dissipative corrections and calculate the damping coefficients for the case of Maxwell-Jüttner statistics.

    Comments:
    11 pages; 3 captioned figures; published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2202.03952 [pdf]
    PRD(2022)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE