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Nuclear Theory·nucl-th

Thursday·February 16, 2017

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 04

    [Submitted on 14 Feb 2017] (cross-list from hep-ph)

    Cosmological CP odd axion field as the coherent Berry's phase of the Universe

    Shuailiang Ge🇨🇦 · Xunyu Liang🇨🇦 · Ariel Zhitnitsky🇨🇦

    We consider a dark matter (DM) model offering a very natural explanation of the observed relation, . This generic consequence of the model is a result of the common origin of both types of matter (DM and visible) which are formed during the same QCD transition. The masses of both types of matter in this framework are proportional to one and the same dimensional parameter of the system, . The focus of the present work is the detail study of the dynamics of the -odd coherent axion field just before the QCD transition. We argue that the baryon charge separation effect on the largest possible scales inevitably occurs as a result of merely existence of the coherent axion field in early Universe. It leads to preferential formation of one species of nuggets on the scales of the visible Universe where the axion field is coherent. A natural outcome of this preferential evolution is that only one type of the visible baryons remains in the system after the nuggets complete their formation. This represents a specific mechanism on how the baryon charge separation mechanism (when the Universe is neutral, but visible part of matter consists the baryons only) replaces the conventional "baryogenesis" scenarios.

    Comments:
    Matches the published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1702.04354 [pdf]
    PRD(2017)·38 citations
  2. 05

    [Submitted on 15 Feb 2017] (cross-list from hep-ph)

    Quark-gluon Vertex: A Perturbation Theory Primer and Beyond

    R. Bermudez🇲🇽 · L. Albino🇲🇽 · L.X. Gutiérrez-Guerrero🇲🇽 · M.E. Tejeda-Yeomans🇲🇽 · A. Bashir🇲🇽

    There has been growing evidence that the infrared enhancement of the form factors defining the full quark-gluon vertex plays an important role in realizing a dynamical breakdown of chiral symmetry in quantum chromodynamics, leading to the observed spectrum and properties of hadrons. Both the lattice and the Schwinger-Dyson communities have begun to calculate these form factors in various kinematical regimes of momenta involved. A natural consistency check for these studies is that they should match onto the perturbative predictions in the ultraviolet, where non-perturbative effects mellow down. In this article, we carry out a numerical analysis of the one-loop result for all the form factors of the quark-gluon vertex. Interestingly, even the one-loop results qualitatively encode most of the infrared enhancement features expected of their non-perturbative counter parts. We analyze various kinematical configurations of momenta: symmetric, on-shell and asymptotic. The on-shell limit enables us to compute anomalous chromomagnetic moment of quarks. The asymptotic results have implications for the multiplicative renormalizability of the quark propagator and its connection with the Landau-Khalatnikov-Fradkin transformations, allowing us to analyze and compare various Anstze proposed so far.

    Comments:
    14 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1702.04437 [pdf]
    PRD(2017)·66 citations
  3. 06

    [Submitted on 15 Feb 2017] (cross-list from hep-lat)

    Third-order perturbative lattice and complex Langevin analyses of the finite-temperature equation of state of non-relativistic fermions in one dimension

    Andrew C. Loheac🇺🇸 · Joaquin E. Drut🇺🇸

    We analyze the pressure and density equations of state of unpolarized non-relativistic fermions at finite temperature in one spatial dimension. For attractively interacting regimes, we perform a third-order lattice perturbation theory calculation, assess its convergence properties by comparing with hybrid Monte Carlo results (there is no sign problem in this regime), and demonstrate agreement with real Langevin calculations. For repulsive interactions, we present lattice perturbation theory results as well as complex Langevin calculations, with a modified action to prevent uncontrolled excursions in the complex plane. Although perturbation theory is a common tool, our implementation of it is unconventional; we use a Hubbard-Stratonovich transformation to decouple the system and automate the application of Wick's theorem, thus generating the diagrammatic expansion, including symmetry factors, at any desired order. We also present an efficient technique to tackle nested Matsubara frequency sums without relying on contour integration, which is independent of dimension and applies to both relativistic and non-relativistic systems, as well as all energy-independent interactions. We find exceptional agreement between perturbative and non-perturbative results at weak couplings, and furnish predictions based on complex Langevin at strong couplings. We additionally present perturbative calculations of up to the fifth-order virial coefficient for repulsive and attractive couplings. Both the lattice perturbation theory and complex Langevin formalisms can easily be extended to a variety of situations including polarized systems, bosons, and higher dimension.

    Comments:
    17 pages, 8 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1702.04666 [pdf]
    PRD(2017)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE