Browsing by Author "Klinkhamer, F.R."

Filter results by typing the first few letters
Now showing 1 - 5 of 5
  • Dark matter from dark energy in q-theory
    (2017-01-01) Klinkhamer, F.R.; Volovik, G. E.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A constant (spacetime-independent) q-field may play a crucial role for the cancellation of Planck-scale contributions to the gravitating vacuum energy density. We now show that a small spacetime-dependent perturbation of the equilibrium q-field behaves gravitationally as a pressureless perfect fluid. This makes the fluctuating part of the q-field a candidate for the inferred dark-matter component of the present universe. For a Planck-scale oscillation frequency of the q-field perturbation, the implication would be that direct searches for dark-matter particles would remain unsuccessful in the foreseeable future.
  • Gluonic vacuum, q-theory, and the cosmological constant
    (2009) Klinkhamer, F.R.; Volovik, Grigory
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In previous work, q-theory was introduced to describe the gravitating macroscopic behavior of a conserved microscopic variable q. In this article, the gluon condensate of quantum chromodynamics is considered in terms of q-theory. The remnant vacuum energy density (i.e., cosmological constant) of an expanding universe is estimated as K3QCD/E2Planck, with string tension KQCD≈(102MeV)2 and gravitational scale EPlanck≈1019GeV. The only input for this estimate is general relativity, quantum chromodynamics, and the Hubble expansion of the present Universe.
  • Propagating q-field and q-ball solution
    (2017) Klinkhamer, F.R.; Volovik, G. E.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    One possible solution of the cosmological constant problem involves a so-called q-field, which self-adjusts so as to give a vanishing gravitating vacuum energy density (cosmological constant) in equilibrium. We show that this q-field can manifest itself in other ways. Specifically, we establish a propagating mode (q-wave) in the nontrivial vacuum and find a particular soliton-type solution in flat spacetime, which we call a q-ball by analogy with the well-known Q-ball solution. Both q-waves and q-balls are expected to play a role for the equilibration of the q-field in the very early universe.
  • Self-tuning vacuum variable and cosmological constant
    (2008) Klinkhamer, F.R.; Volovik, Grigory
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A spacetime-independent variable is introduced which characterizes a Lorentz-invariant self-sustained quantum vacuum. For a perfect (Lorentz-invariant) quantum vacuum, the self-tuning of this variable nullifies the effective energy density which enters the low-energy gravitational field equations. The observed small but nonzero value of the cosmological constant may then be explained as corresponding to the effective energy density of an imperfect quantum vacuum (perturbed by, e.g., the presence of thermal matter).
  • Vacuum energy density kicked by the electroweak crossover
    (2009) Klinkhamer, F.R.; Volovik, Grigory
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Using q-theory, we show that the electroweak crossover can generate a remnant vacuum energy density Λ∼E8ew/E4Planck, with effective electroweak energy scale Eew∼103  GeV and reduced Planck-energy scale EPlanck∼1018  GeV. The obtained expression for the effective cosmological constant Λ may be a crucial input for the suggested solution by Arkani-Hamed et al. of the triple cosmic coincidence puzzle (why the orders of magnitude of the energy densities of vacuum, matter, and radiation are approximately the same in the present Universe).