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Register a new userOn the relation between mass of pion, fundamental physical constants and cosmological parameters
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Authors
Dragan Slavkov Hajdukovic
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In this article we reconsider the old mysterious relation, advocated by Dirac and Weinberg, between the mass of the pion, the fundamental physical constants, and the Hubble parameter. By introducing the cosmological density parameters, we show how the corresponding equation may be written in a form that is invariant with respect to the expansion of the Universe and without invoking a varying gravitational constant, as was originaly proposed by Dirac. It is suggest that, through this relation, Nature gives a hint that virtual pions dominante the content of the quantum vacuum.
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The observed constraints on the variability of the proton to electron mass ratio $mu$ and the fine structure constant $alpha$ are used to establish constraints on the variability of the Quantum Chromodynamic Scale and a combination of the Higgs Vacuum Expectation Value and the Yukawa couplings. Further model dependent assumptions provide constraints on the Higgs VEV and the Yukawa couplings separately. A primary conclusion is that limits on the variability of dimensionless fundamental constants such as $mu$ and $alpha$ provide important constraints on the parameter space of new physics and cosmologies.
Contemporary multidimensional cosmological theories predict different variations of fundamental physical constants in course of the cosmological evolution. On the basis of the QSO spectra analysis, we show that the fine-structure constant alpha=e^2/(hbar c) and the proton-to-electron mass ratio mu=m_p/m_e reveal no statistically significant variation over the last 90% of the lifetime of the Universe. At the 2sigma significance level, the following upper bounds are obtained for the epoch corresponding to the cosmological redshifts z ~ 3 (i.e., ~ 10 Gyr ago): |Deltaalpha/alpha| < 0.00016 and |Deltamu/mu| < 0.00022. The corresponding upper limits to the time-average rates of the constant variations are |dalpha/(alpha dt)| < 1.6times 10^{-14} yr^{-1} and |dmu/(mu dt)| < 2.2times10^{-14} yr^{-1}. These limits serve as criteria for selection of those theoretical models which predict alpha and mu variation with the cosmological time. In addition, we test a possible anisotropy of the high-redshift fine splitting over the celestial sphere, which might reveal a non-equality of alpha values in causally disconnected areas of the Universe.
We provide an overview of RBC/UKQCDs charm project on 2+1 flavour physical pion mass ensembles using Mobius Domain Wall Fermions for the light as well as for the charm quark. We discuss the analysis strategy in detail and present results at the different stages of the analysis for $D$ and $D_s$ decay constants as well as the bag and $xi$ parameters. We also discuss future approaches to extend the reach in the heavy quark mass.
The cosmological constant $Lambda$ is a free parameter in Einsteins equations of gravity. We propose to fix its value with a boundary condition: test particles should be free when outside causal contact, e.g. at infinity. Under this condition, we show that constant vacuum energy does not change cosmic expansion and there can not be cosmic acceleration for an infinitely large and uniform Universe. The observed acceleration requires either a large Universe with evolving Dark Energy (DE) and equation of state $omega>-1$ or a finite causal boundary (that we call Causal Universe) without DE. The former cant explain why $Omega_Lambda simeq 2.3 Omega_m$ today, something that comes naturally with a finite Causal Universe. This boundary condition, combined with the anomalous lack of correlations observed above 60 degrees in the CMB predicts $Omega_Lambda simeq 0.70$ for a flat universe, with independence of any other measurements. This solution provides new clues and evidence for inflation and removes the need for Dark Energy or Modified Gravity.
Two dimensionless fundamental physical constants, the fine structure constant $alpha$ and the proton-to-electron mass ratio $frac{m_p}{m_e}$ are attributed a particular importance from the point of view of nuclear synthesis, formation of heavy elements, planets, and life-supporting structures. Here, we show that a combination of these two constants results in a new dimensionless constant which provides the upper bound for the speed of sound in condensed phases, $v_u$. We find that $frac{v_u}{c}=alphaleft(frac{m_e}{2m_p}right)^{frac{1}{2}}$, where $c$ is the speed of light in vacuum. We support this result by a large set of experimental data and first principles computations for atomic hydrogen. Our result expands current understanding of how fundamental constants can impose new bounds on important physical properties.
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