Temperature dependence of coupling constants

We study the temperature-dependence of coupling constants at the one-loop level for massive ?⁴ theory and massive scalar electrodynamics (SED). It is found that the scalar coupling constant λ for m² > 0 decreases with temperature leading to a phase transition to a non-interacting phase. In a model with m² < 0, λ increases as 1n T. The gauge coupling constant of SED increases uniformly with temperature.     

Hyperfine coupling constants in muonium adducts of the carbonyl bond

A representative series is studies of organic radicals formed by the effective addition of muonium to the carbonyl oxygen atom of aldehydes, ketones, esters and amides. Low values of the muonelectron hyperfine coupling are measured which are particularly sensitive to radical structure and dynamics. The systematics of these values are discussed in terms of the opposing contributions of conjugation and hyperconjugation.     

Curvature dependence of renormalized coupling constants

The renormalization group is used to analyze the behavior of certain gravitationally significant renormalized coupling constants under a scaling of the spacetime curvature. After discussing a simple example, the results are summarized for a class of grand unified theories.     

Hyperfine coupling constants of cesium 7D states using two-photon spectroscopy

Doppler-free two-photon transitions of cesium 6S_1/2→7D_{3/2, 5/2} were observed in a thermal stabilized cell. A repeated spectrum of 75 MHz introduced from the side band of an electro-optical modulator served as a frequency marker to improve the accuracy of frequency measurement. The hyperfine magnetic dipole constant A and electrical quadrupole constant B of Cs 7D_{3/2, 5/2} can be derived from the splitting intervals of the observed spectra. The results are: A=7.36(07) MHz, B=−0.88(87) MHz for the 7D_3/2 state, and A=−1.81(05) MHz, B=1.01(1.06) MHz for the 7D_5/2 state. These coefficients are improvements for testing high-precision measurements and determining fundamental physical constants.     

Model dependence of charge densities determined from electron scattering

A new method is used to analyze recent experiments on electron scattering on ³He in the high momentum transfer region. The accuracy of the new measurements is very high so that the charge density can be determined with much higher accuracy than before. We find that further reduction of the error in charge density can only be achieved by a more accurate measurement of the region 3 < q < 6 fm^?1. Continuing the previous work of Hetherington and Borysowicz, a very useful approximate relation is derived between the error of charge density and the error of measurements of form factor. We find that linear expansion methods lead to similar results as the present method. They require, however, stronger asymptotic assumptions about ?(r).     

Hyperfine coupling temperature dependence of Mn2+ in CaF2

The hyperfine coupling constant for Mn²⁺ located in cubic sites of CaF₂ was measured over the temperature range 77 to 850°K by electron spin resonance techniques. The temperature dependence has been interpreted using the Šimánek-Orbach theory of a phonon-induced hyperfine field.     

Extraction of nuclear coupling constants from data on nuclear charge form factors

A possibility of extracting nuclear coupling constants from data on nuclear charge form factors is discussed. The method exploits analytic properties of form factors in the momentum transfer plane. As an illustration the form factor of⁴He is considered in detail. In this case the value \(g_{4_{He^3 He(^3 H)} }^2 /4\pi = 16 \pm 1\) has been obtained in excellent agreement with earlier determinations by means of other methods. Similar analysis of the¹⁶O form factor yields the first estimate of the oxygen-nucleon coupling∶ \(g_{16_{O^{15} O(^{15} N)N} }^2 /4\pi = 64\) .     

Calculated band structures,optical constants and electronic charge densities for InAs and InSb

The energy band structure, reflectivity, modulated reflectivity and imaginary part of the frequency dependent dielectric function are calculated for InAs and InSb using the empirical pseudopotential method. Comparison is made with the measured reflectivity and modulated reflectivity and prominent features in the experimental spectra are identified and associated with interband transitions in specific regions of the Brillouin zone. The wavefunctions obtained from our calculated band structures are used to calculate the electronic charge density as a function of position in the unit cell.     

The fundamental constants in physics and their time dependence

We discuss the fundamental constants in the Standard Model of particle physics. Furthermore we discuss possible changes of these constants on the cosmological time scale. The Grand Unification of the observed strong, electromagnetic and weak interactions implies relations between the time variations of the finestructure constant α and of the QCD scale Λ_c. A change of α by 10⁻¹⁵/year, as seen by an astrophysics experiment, implies a time variation of Λ_c of at least 10⁻¹⁵/year. An experiment in Quantum Optics, which was designed to look for a time variation of Λ_c, is discussed.     

The conformational dependence of vicinal 15N-C-C-H coupling constants in peptides

The conformational dependence of vicinal ¹⁵N-C-C-H coupling in N-methylacetamide as a model compound for coupling in the peptide backbone is investigated by means of the self-consistent perturbation formulation for coupling constants in the INDO approximation of self-consistent-field molecular orbital theory. Because the calculated coupling constants cover a range of at least 7 Hz, they should be useful in determining the ψ angles in peptides. The prediction of opposite signs for gauche and trans coupling indicates the need for sign determination. Non-negligible coupling constants of positive sign for the gauche arrangements are undoubtedly due to a substituent effect involving the lone pair electrons on the nitrogen and the π-electrons of the carbonyl group. Calculated results are compared with the available experimental data.     

Temperature dependence of coupling constants and the phase transition in the Coleman-Weinberg theory

It is shown that the temperature dependence of the effective Higgs boson coupling constants leads to a considerable modification of the theory of the SU(5) Coleman-Weinberg phase transition.     

Hyperfine coupling constants of NCO in ÃΣ by sub-Doppler spectroscopy

Molecular constants including ¹⁴N hyperfine coupling constants of the NCO radical in the òΣ⁺(000) state have been determined precisely by using the microwave-optical double resonance (MODR) and intermodulated fluorescence (IMF) techniques, where the band was pumped by a dye laser. The results are B = 12 056.559(41), D = 0.0045(16), γ = 22.06(17), b = 430.4(12), c = 80.3(28), and eQq = 2.6(36), all in MHz with one standard error in parentheses. It was found that, because the òΣ⁺ state closely approximates a coupling case (b_βS), MODR did not provide any precise value for the Fermi contact term, but this constant was determined accurately by combining the MODR spectrum with the IMF spectrum.     

Localizability and coupling constants

Let us consider for free elementary systems the postulates: (i) localizability of systems would not favor in a physical sense some inertial frames and that (ii) standard quantum mechanics (or, at least, a skeleton of it) applies for localizability. It is known that, at least for the lower values of spin, (i) and (ii) imply a unique solution of the localization problem for the no-interaction case. Extrapolating the analysis to the case when interactions are present, we offer arguments in favor of theconjecture that if elementary systems under interaction are localizable, then (i) and (ii) imply restrictions on the coupling constants, and probably their single-valuedness.     

Hyperfine spectra and molecular constants of D2S

A millimeter wave molecular beam maser has been used to resolve the nuclear hyperfine structure of the 1₁₀ → 1₀₁ transition of D₂S at 91.4 Gc/sec. This data, combined with that previously obtained for H₂S and HDS, allows a determination of the molecular constants of hydrogen sulfide. The quadrupole coupling constants for D₂S are (eQq_j)₁₁₀ = 17.83 ± 0.15 kc/sec and (eQq_j)₁₀₁ = −10.82 ± 0.28 kc/sec. The components of χ_ii = eQ_Dq_ii in its principal axis system are χ_xx = 149.0 kc/sec, χ_yy = −59.8 kc/sec, and χ_zz = −89.2 kc/sec, where the z axis is perpendicular to the plane of the molecule and the x axis is rotated 1°35′ from the DS bond in the direction away from the D-S-D obtuse angle.