Fundamental Constant Observational Bounds on the Variability of the QCD Scale

Many physical theories beyond the Standard Model predict time variations of basic physics parameters. Direct measurement of the time variations of these parameters is very difficult or impossible to achieve. By contrast, measurements of fundamental constants are relatively easy to achieve, both in the laboratory and by astronomical spectra of atoms and molecules in the early universe. In this work measurements of the proton to electron mass ratio $\mu$ and the fine structure constant $\alpha$ are combined to place mildly model dependent limits on the fractional variation of the Quantum Chromodynamic Scale and the sum of the fractional variations of the Higgs Vacuum Expectation Value and the Yukawa couplings on time scales of more than half the age of the universe. The addition of another model parameter allows the fractional variation of the Higgs VEV and the Yukawa couplings to be computed separately. Limits on their variation are found at the level of less than $5 \times 10^{-5}$ over the past seven gigayears. A model dependent relation between the expected fractional variation of $\alpha$ relative to $\mu$ tightens the limits to $10^{-7}$ over the same time span. Limits on the present day rate of change of the constants and parameters are then calculated using slow roll quintessence. A primary result of this work is that studies of the dimensionless fundamental constants such as $\alpha$ and $\mu$, whose values depend on the values of the physics parameters, are excellent monitors of the limits on the time variation of these parameters.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Society, 8 pages, 5 figure

The Relation Between Fundamental Constants and Particle Physics Parameters

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.Comment: Published in the proceedings of the Conference on Varying Constants and Fundamental Cosmology VARCOSMOFUN16. Modified from the Universe style to process properly in arXi

Confronting Cosmology and New Physics with Fundamental Constants

The values of the fundamental constants such as $\mu = m_P/m_e$, the proton to electron mass ratio and $\alpha$, the fine structure constant, are sensitive to the product $\sqrt{\zeta_x^2(w+1)}$ where $\zeta_x$ is a coupling constant between a rolling scalar field responsible for the acceleration of the expansion of the universe and the electromagnetic field with x standing for either $\mu$ or $\alpha$. The dark energy equation of state $w$ can assume values different than $-1$ in cosmologies where the acceleration of the expansion is due to a scalar field. In this case the value of both $\mu$ and $\alpha$ changes with time. The values of the fundamental constants, therefore, monitor the equation of state and are a valuable tool for determining $w$ as a function of redshift. In fact the rolling of the fundamental constants is one of the few definitive discriminators between acceleration due to a cosmological constant and acceleration due to a quintessence rolling scalar field. $w$ is often given in parameterized form for comparison with observations. In this manuscript the predicted evolution of $\mu$, is calculated for a range of parameterized equation of state models and compared to the observational constraints on $\Delta \mu / \mu$. We find that the current limits on $\Delta \mu / \mu$ place significant constraints on linear equation of state models and on thawing models where $w$ deviates from $-1$ at late times. They also constrain non-dynamical models that have a constant $w$ not equal to $-1$. These constraints are an important compliment to geometric tests of $w$ in that geometric tests are sensitive to the evolution of the universe before the epoch of observation while fundamental constants are sensitive to the evolution of the universe after the observational epoch. Abstract truncated.Comment: To appear in the conference proceedings of the Sesto Conference on Fundamental Constants and Coupling

Beta Function Quintessence Cosmological Parameters and Fundamental Constants I: Power and Inverse Power Law Dark Energy Potentials

This investigation explores using the beta function formalism to calculate analytic solutions for the observable parameters in rolling scalar field cosmologies. The beta function in this case is the derivative of the scalar $\phi$ with respect to the natural log of the scale factor $a$, $\beta(\phi)=\frac{d \phi}{d \ln(a)}$. Once the beta function is specified, modulo a boundary condition, the evolution of the scalar $\phi$ as a function of the scale factor is completely determined. A rolling scalar field cosmology is defined by its action which can contain a range of physically motivated dark energy potentials. The beta function is chosen so that the associated "beta potential" is an accurate, but not exact, representation of the appropriate dark energy model potential. The basic concept is that the action with the beta potential is so similar to the action with the model potential that solutions using the beta action are accurate representations of solutions using the model action. The beta function provides an extra equation to calculate analytic functions of the cosmologies parameters as a function of the scale factor that are that are not calculable using only the model action. As an example this investigation uses a quintessence cosmology to demonstrate the method for power and inverse power law dark energy potentials. An interesting result of the investigation is that the Hubble parameter H is almost completely insensitive to the power of the potentials and that $\Lambda$CDM is part of the family of quintessence cosmology power law potentials with a power of zero.Comment: Accepted for publication by the Monthly Notices of the Royal Astronomical Societ

Beta function quintessence cosmological parameters and fundamental constants – II. Exponential and logarithmic dark energy potentials

This paper uses the beta function formalism to extend the analysis of quintessence cosmological parameters to the logarithmic and exponential dark energy potentials. The previous paper demonstrated the formalism using power and inverse power potentials. The essentially identical evolution of the Hubble parameter for all of the quintessence cases and Lambda CDM is attributed to the flatness of the quintessence dark energy potentials in the dark energy dominated era. The Hubble parameter is therefore incapable of discriminating between static and dynamic dark energy. Unlike the other three potentials considered in the two papers the logarithmic dark energy potential requires a numerical integration in the formula for the superpotential rather than being an analytic function. The dark energy equation of state and the fundamental constants continue to be good discriminators between static and dynamical dark energy. A new analysis of quintessence with all four of the potentials relative the swampland conjectures indicates that the conjecture on the change in the scalar field is satisfied but that the conjecture on the change of the potential is not.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Paper Session II-A - The Future of Hubble Space Telescope Science

The Hubble Space Telescope, HST, is a unique platform for new science. Each mission to HST is a complex dance of engineering, astronautics, and science that brings new scientific opportunities to the telescope. Through new instruments, new discoveries and new insights, HST’s role as the premier space astronomical instrument will continue into the next millennium. The 1997 maintenance mission will give HST infrared eyes to peer far back in time and space as well as into the birth places of galaxies, stars and planets. It will multiply HST’s spectroscopic grasp many fold to increase our knowledge of distant quasars and nearby planets. In many respects HST creates its own future through its revelations about our universe. This talk is a small selection of what lies ahead