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Nuclear Theory·nucl-th

Tuesday·November 10, 2020

16 papers—11 primary·5 cross-listed

All16Primary11Cross-lists5
  1. 12

    [Submitted on 7 Nov 2020] (cross-list from hep-ph)

    Magnetic field dependence of the neutral pion mass in the linear sigma model with quarks: The strong field case

    Alejandro Ayala🇲🇽 · José Luis Hernández🇲🇽 · L. A. Hernández🇲🇽 · Ricardo L. S. Farias🇧🇷 · R. Zamora🇨🇱

    We use the linear sigma model with quarks to find the magnetic field-induced modifications to the neutral pion mass at one-loop level. The magnetic field effects are introduced by using charged particle propagators in the presence of a magnetic background in the strong field regime. We show that when accounting for the effects of the magnetic field on the model couplings, the vacuum sigma field and the neutral pion self-energy, the neutral pion mass decreases monotonically as a function of the field strength. We find an excellent qualitative and quantitative agreement with recent lattice QCD calculations, reproducing the monotonically decreasing trend with the field strength as well as the decrease when lattice data approaches the physical vacuum pion mass from larger values.

    Comments:
    14 pages, 10 figures, expanded discussion, conclusions unchanged, version to appear in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.03673 [pdf]
    PRD(2021)·38 citations
  2. 13

    [Submitted on 7 Nov 2020] (cross-list from hep-th)

    Hydrodynamic effective field theory and the analyticity of hydrostatic correlators

    Akash Jain🇨🇦 · Pavel Kovtun🇨🇦 · Adam Ritz🇨🇦 · Ashish Shukla🇨🇦

    We study one-loop corrections to retarded and symmetric hydrostatic correlation functions within the Schwinger-Keldysh effective field theory framework for relativistic hydrodynamics, focusing on charge diffusion. We first consider the simplified setup with only diffusive charge density fluctuations, and then augment it with momentum fluctuations in a model where the sound modes can be ignored. We show that the loop corrections, which generically induce non-analyticities and long-range effects at finite frequency, non-trivially preserve analyticity of retarded correlation functions in spatial momentum due to the KMS constraint, as a manifestation of thermal screening. For the purposes of this analysis, we develop an interacting field theory for diffusive hydrodynamics, seen as a limit of relativistic hydrodynamics in the absence of temperature and longitudinal velocity fluctuations.

    Comments:
    24+1 pages. v2: References added, typos fixed, matches version published in JHEP
    Subjects:
    High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
    arXiv:
    2011.03691 [pdf]
    JHEP(2021)·27 citations
  3. 14

    [Submitted on 8 Nov 2020] (cross-list from hep-th)

    Lipkin model on a quantum computer

    Michael J. Cervia🇺🇸 · A. B. Balantekin🇺🇸 · S. N. Coppersmith🇺🇸 · Calvin W. Johnson🇺🇸 · Peter J. Love🇺🇸 · C. Poole🇺🇸 · K. Robbins🇺🇸 · M. Saffman🇺🇸

    Atomic nuclei are important laboratories for exploring and testing new insights into the universe, such as experiments to directly detect dark matter or explore properties of neutrinos. The targets of interest are often heavy, complex nuclei that challenge our ability to reliably model them (as well as quantify the uncertainty of those models) with classical computers. Hence there is great interest in applying quantum computation to nuclear structure for these applications. As an early step in this direction, especially with regards to the uncertainties in the relevant quantum calculations, we develop circuits to implement variational quantum eigensolver (VQE) algorithms for the Lipkin-Meshkov-Glick model, which is often used in the nuclear physics community as a testbed for many-body methods. We present quantum circuits for VQE for two and three particles and discuss the construction of circuits for more particles. Implementing the VQE for a two-particle system on the IBM Quantum Experience, we identify initialization and two-qubit gates as the largest sources of error. We find that error mitigation procedures reduce the errors in the results significantly, but additional quantum hardware improvements are needed for quantum calculations to be sufficiently accurate to be competitive with the best current classical methods.

    Comments:
    11 pages of RevTeX, 8 figures
    Subjects:
    High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2011.04097 [pdf]
    PRC(2021)·74 citations
  4. 15

    [Submitted on 9 Nov 2020] (cross-list from hep-ph)

    One-loop Kubo estimations of the shear and bulk viscous coefficients for hot and magnetized Bosonic and Fermionic systems

    Snigdha Ghosh🇮🇳 · Sabyasachi Ghosh🇮🇳

    The expressions of the shear viscosity and the bulk viscosity components in the presence of an arbitrary external magnetic field for a system of hot charged scalar Bosons (spin-0) as well as for a system of hot charged Dirac Fermions (spin-) have been derived by employing the one-loop Kubo Formalism. This is done by explicitly evaluating the thermo-magnetic spectral functions of the energy momentum tensors using the real time formalism of finite temperature field theory and the Schwinger proper time formalism. In the present work, a rich quantum field theoretical structure in the expressions of the viscous coefficients in non-zero magnetic field are found, which are different from their respective expressions obtained earlier via kinetic theory based calculations; though, in absence of magnetic field, the one-loop Kubo and the kinetic theory based expressions for the viscosities are known to be identical. We have identified that Kubo and kinetic theory based results of viscosity components follow similar kind of temperature and magnetic field dependency. The relaxation time and the synchrotron frequency in the kinetic theory formalism are realized to be connected respectively with the thermal width of propagator and the transitions among the Landau levels of the charged particles in the Kubo formalism. We believe that, the connection of latter quantities are quite new and probably the present work is the first time addressing this interpretation along with the new expressions of viscosity components, not seen in existing works.

    Comments:
    Version published in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.04261 [pdf]
    PRD(2021)·29 citations
  5. 16

    [Submitted on 9 Nov 2020] (cross-list from hep-ph)

    Novel Rosenbluth Extraction Framework for Compton Form Factors from Deeply Virtual Exclusive Experiments

    Brandon Kriesten · Simonetta Liuti

    We use a generalization of the Rosenbluth separation method for a model independent simultaneous extraction of the Compton Form Factors and , from virtual Compton scattering data on an unpolarized target. A precise evaluation of and , enabled by the proposed method, is the first step towards pinning down the the distribution of angular momentum inside the proton.

    Comments:
    5 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2011.04484 [pdf]
    PLB(2022)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE