Fundamental Coupling Constants Research Articles

The trace anomaly and low energy phenomenological implications of wormholes

In Coleman's wormhole scenario it is the trace anomaly on S 4 that controls the behavior of fundamental coupling constants, particle masses, mixing angles, etc. We indicate how low energy phenomenology may be derivable from very general properties of wormhole physics and calculable β-functions, etc.

Essay on gravitation: Present-time variation of Newton's gravitational constant in superstring theories

Superstring theories provide an appropriate framework for studying the time variation of fundamental coupling constants. The present time variation of coupling constants in Superstring theories with currently favorable internal backgrounds critically depends on the shape of the potential for the size of internal space. If the potential is almost flat, as in perturbation theory to all orders, the present value of ¦Ġ/G¦ for Newton's gravitational constant is calculable and estimated to be 1×10−11±1yr−1, which is just at the edge of the present observational bound forĠ/G. If the potential has a minimum with finite curvature due to unknown nonperturbative effects,Ġ/G will become unobservably small. The improvement of the measurement ofĠ/G of 1 or 2 orders of magnitude would discriminate between the two situations. Problems with the time variation of other coupling constants are also discussed.

Implications of anomalous isospin violation for the low energy nucleon-nucleon interaction

Quark mass differences are used to derive an anomalous (i.e., due to the strong interactions) isospin violating potential. The potential includes the effects of pseudoscalar ($\ensuremath{\pi}\ensuremath{-}\ensuremath{\eta}\ensuremath{-}{\ensuremath{\eta}}^{\ensuremath{'}}$) and vector meson ($\ensuremath{\rho}\ensuremath{-}\ensuremath{\omega}$) mixing. The finite $\ensuremath{\rho}$ width is included. Low energy $\mathrm{nn}$, $\mathrm{pp}$, and $\mathrm{np}$ phase shift differences are calculated in terms of the fundamental coupling constants. Despite considerable uncertainty in the coupling constants, it is possible to understand the very small $\mathrm{nn}$ and $\mathrm{pp}$ scattering length differences. Furthermore, it appears that effects in the $l>0$ partial waves at finite energies are large enough to be observable in the next few years. Estimates of effects in bound nuclei are presented. These include calculations of the contributions to mirror nuclei binding energy differences and to isospin mixing for a few characteristic cases. In most of those cases the anomalous isospin breaking contributions are of roughly the same size as observed discrepancies. However, inclusion of short range correlations substantially reduces the calculated effects in these cases.NUCLEAR REACTIONS $\mathrm{pp}$, $\mathrm{pn}$, and $\mathrm{nn}$ elastic scattering, $E=0\ensuremath{-}350$ MeV, calculated phase shift differences due to anomalous isospin breaking. Effects in finite nuclei estimated.

Magnitude of large-transverse-momentum cross sections

Consistent values for the fundamental dimensional coupling constants of hadrons to their valence quarks are determined from large-momentum-transfer elastic scattering, photoproduction, form factors, and momentum distributions. We then show that the constituent-interchange-model hard-scattering subprocesses Mq ..-->.. Mq and Bq ..-->.. Bq (and their crossing variants) are of sufficient magnitude to account for the normalization as well as the kinematic behavior in p/sub T/, angle, and s of single-particle large-transverse-momentum inclusive cross sections. The crossover point where p/sub T//sup -4/ scale-invariant qq ..-->.. qq and gluon terms may dominate the cross section is computed. Jet cross sections and charge correlations are also discussed. We also give analytic formulas for inclusive cross sections in general hard-scattering models. Spectator and dimensional-counting rules are given which determine the scaling behavior in p/sub T/, epsilon = M/sup 2//s, and theta/sub c.m./.

Gravity and inertia in a Machian framework

It is suggested that Mach's principle as originally conceived in prerelativistic physics is equivalent to the requirement that the laws of dynamics be invariant under the groupr→A(λ)·r+g(λ), λ→f(λ), where λ is an arbitrary time parameter,A is an orthogonal matrix, andA, g andf are arbitrary functions of λ. This group is called the Leibniz group. The general properties of theories that are invariant under this group are studied. They differ strongly from those of more conventional theories: there is no independent time and no fundamental coupling constants; spherically symmetric cosmological solutions are unique; the equations describing the motion of the Universe as a whole (protophysics) are quite different from the equations describing the motion of local bodies in a given cosmological environment (local physics); the strengths of forces observed locally are determined cosmologically. A particular Leibniz-invariant theory is used to demonstrate these properties. It is shown that in a certain limit, called the cosmological limit, the local dynamics is Galileo invariant, in contrast to the Leibniz-invaraint protophysics. The local dynamics obtained for the solar system reduces to Newtonian dynamics with a small correction. The correct order of magnitude of the gravitational constant is obtained. Under the assumption that planetary dynamics is described by the local dynamics, three independent predictions about the bulk parameters of the Universe can be made. All three agree suprisingly well with current observations. The most striking feature of the local dynamics is that it contains a distinguished velocityv determined by the average motion of the Universe. For the particular model studied here,v=2.45·1010 cm/s. It is suggested on the basis of this result that the velocity of light and special relativity could reflect the imprint of the Universe at large on local physics. The theory in its present form is still very rudimentary and incomplete and so far merely provides the framework of a Machian theory of gravity and inertia. In particular, the behaviour of rods and clocks and the related problem of the anisotropy of inertial mass can be fully understood only when the rest of physics has been brought into this Machian framework.

A fundamental theory of the half-shell t-matrix for nucleon-nucleon scattering

A theory of the half-shell t-matrix for nucleon-nucleon scattering which is expressible directly in terms of the fundamental relativistic meson-theoretic amplitudes, which latter correspond to manifestly nonlocal and energy-dependent interactions, and which are universal for all states of the nucleon-nucleon system, is developed through the use of analyticity and dispersion theory. The theory is, in principle, free from unknown and arbitrary parameters, requiring as input only the measurable phase shifts and inelasticity parameters for all energies and the fundamental meson-nucleon coupling constants and their associated from factors. In addition to being able to incorporate in a natural way the inelasticities which arise from the mesonic degrees of freedom in the nucleon-nucleon interaction, as well as the bound states and the spin coupling, the theory also provides a convenient framework for obtaining useful insights into the strong-interaction dynamical mechanism underlying the half-shell t-matrix. In light of the fact that this t-matrix is quite sensitive to the short-distance behavior of the nucleon-nucleon interaction, where the description in terms of a potential may be unreliable and ambiguous, it is noteworthy that the theory provides a general framework for going beyond the potential-theoretic description of this interaction. Within the framework of the relativistic one-boson-exchange models, a detailed study of the half-shell t-matrix in the 1 S 0 and 1 P 1 states is presented, with emphasis on the dynamical insights. Some idea of its sensitivity to the present uncertainties in the phase shifts and inelasticities, as well as that in the fundamental coupling constants, is also provided. Finally, the t-matrix is compared with those obtained using the Reid local soft-core potentials.

A proton and lithium-7 NMR investigation of triphenyl group IV lithium compounds

The proton NMR spectra of the triphenyl group IV lithium compounds have been analysed exactly in terms of the fundamental parameters, chemical shifts, and coupling constants. The para proton chemical shifts are consistent with electron donation from the group IV atom into the phenyl rings, as was reported previously. However, the para protons are shielded in the opposite order from that expected on the basis of the π-bonding trends of the group IV atoms. The 7Li NMR spectra were also obtained for information concerning the association between Li and the group IV atom. The data indicate that the degree of electron delocalization into the phenyl rings is controlled by the degree of association between lithium and the group IV atom.