Fluid-dynamical description of nuclear collective excitations

The role of antisymmetric tensor fields in the gauging of groups is related to theorems on cohomology theory, and Cartan integrable systems are discussed. Examples are given. Various possibilities to gauge d = 11 supergravity by decontracting its underlying group are considered. In particular the simple supergroups Osp (1 | 64) and SU(32 | 1) yield a negative result, but a certain non-semisimple supergroup containing Osp (1 | 32) is proposed as a viable candidate. The corresponding action would no longer contain the 3-index photon A_μν?, but instead a second spin $\text{3}\text{2}$ field η_μ and boson fields $\text{B}{}_{\mathrm{\mu }}{}^{\mathrm{a1a2}}$ and $\text{B}{}_{\mathrm{\mu }}{}^{\mathrm{a1\dots a5}}$. A first order formalism for d = 11 is presented. It is to be used for an improved form of dimensional reduction.     

Chiral ward identities,effective actions and meson-glueball mixing

The low-energy spectrum of 1⁺ and 0^? mesons in one-flavour QCS is investigated. It is shown that there exist two light pseudoscalar mesons, which are linear combinations of pure quark and pure glueball states. Simple relations implied by the axial anomaly for their decay constants are confirmed. The mass generation mechanism for the lightest pseudoscalar meson is identified as due to the mixing of the operators $\text{i}\text{ψ}\text{γ}{}_5\text{ψ}$ and $\text{(?}\text{g}{}^2\text{16π}{}^2\text{)}{}^1\text{F}{}_{\mathrm{\mu \nu }}{}^{\mathrm{a}}\text{F}{}^{\mathrm{a\mu \nu }}$, and the U(1) problem in this model is resolved. To establish these results, new functional methods are developed to determine the effective action for the appropriate fields in a low-energy approximation. A novel feature of our work is the introduction of a “symmetric” effective action, defined using a non-standard Legendre transform. The anomalous chiral Ward identities imply a simple invariance property for this functional, enabling it to be constructed in a particularly systematic way. Finally, the relation of our general results to the literature on effective lagrangians in the $\text{1}\text{N}$ approximation is discussed.     

Poincaré gauge invariance and the dynamical role of spin in gravitational theory

We classify, according to the number of independent gauge fields, Poincaré gauge invariant theoretical frameworks of describing gravity into three categories. One of them may provide the dynamical definition of the spin tensor S and that of the energy-momentum tensor T, resulting in the response equation of matter to gravity with the gravitational field strengths, D′ and F, coupled to the former tensors

$\text{T}{}_{\mathrm{\nu }}{}^{\mathrm{\mu }}\text{;}{}_{\mathrm{\mu }}\text{=D′}{}_{\mathrm{\mu \lambda \nu }}\text{T}{}^{\mathrm{\mu \lambda }}\text{+F}{}_{\mathrm{\mu \lambda \nu \rho }}\text{S}{}^{\mathrm{\rho \mu \lambda }}$

, where the right-hand side represents spin force densities. In the absence of spin the response reduces to the conventional one of general relativity, i.e., without the spin forces. For the electromagnetic field the phase-gauge invariance requires the same conclusion as for a scalar field. For a spin $\text{1}\text{2}$ particle there is torsion, which deflects its trajectory from geodesic; an explicit expression for torsion takes a simple form of the axial vector current $\text{ψ}\text{γ}{}_5\text{γ}{}_{\mathrm{k}}\text{ψ}$.     

Gauge theory and bags

The surface dependent phase factor $\text{P}\text{(}\text{exp}\text{∫}\text{F}{}_{\mathrm{\mu \nu }}{}^1\text{d}\text{σ}{}^{\mathrm{\mu \nu }}$) is introduced and its variational derivatives are investigated. Under certain assumptions it is shown to satisfy a differential equation which coincides with the membrane equation.     

νW2 at small ω′ and resonance form factors in a quark model with broken SU(6)

The small ω′ behaviour of F₂^en/F₂^ep and the apparent difference in the q² dependences of the magnetic form factor of the proton and of the transition to Δ⁺(1236) are quantitatively correlated in a model where nucleon consistes of a quarks and a scalar or vector core. The proton and Δ transition form factors suggest that only the scalar core contributes at large q² and small ω′. As a result the ω′ dependence of $\text{F}{}_2{}^{\mathrm{<mtext>en</mtext>}}\text{F}{}_2{}^{\mathrm{<mtext>ep</mtext>}}$ is obtained for ω′ < 3 and predictions for the weak structure functions and polarisation asymmetries at smallω′ are presented. We predict $\text{F}{}^{\mathrm{<mtext>\nu </mtext><mtext>p</mtext>}}\text{F}{}^{\mathrm{<mtext>\nu </mtext><mtext>n</mtext><mtext>\omega \prime \to 1</mtext><mtext>0</mtext>}}$ asymmetries $\text{ω′→1}\text{1}$ and also expect that $\text{G}{}_{\mathrm{<mtext>m</mtext>}}{}^{\mathrm{<mtext>n</mtext>}}\text{G}{}_{\mathrm{<mtext>m</mtext>}}{}^{\mathrm{<mtext>p</mtext>}}\text{→}\text{?1}\text{2}$ as q²→∞.     

Exact solutions of the Loretnz-Dirac equations of motion for charged particles in constant electromagnetic fields

The linearized Lorentz-Dirac equation $\text{u}\text{?}{}^{\mathrm{\mu }}\text{= F}{}^{\mathrm{\mu \nu }}\text{u}{}_{\mathrm{\nu }}\text{- κ(F}{}^{\mathrm{\mu \sigma }}\text{F}{}_{\mathrm{\lambda \sigma }}\text{u}{}^{\mathrm{\lambda }}\text{+ {F}{}^{\mathrm{\sigma \mu }}\text{u}{}_{\mathrm{\nu }}\text{F}{}_{\mathrm{\sigma \lambda }}\text{u}{}^{\mathrm{\lambda }}\text{}u}{}^{\mathrm{\mu }}\text{)}$ is solved in closed form for arbitrary constant electromagnetic fields. These solutions are also a convenient starting point to treat particle motion in the slowly varying electromagnetic fields surrounding a pulsar in the near field zone.     

On investigating the structure of hadrons: Lattice Monte Carlo measurements of colour magnetic and electric fields and the topological charge density inside glueballs

We present some techniques for elucidating hadronic structure via lattice Monte Carlo calculations. Applying these techniques, we measure the fluctuations of colour magnetic and electric fields as well as the topological charge density inside and outside the lowest lying 0⁺ and 2⁺ glueballs in the SU(2) non-abelian lattice gauge theory. This gives us a picture of the glueball structure. We also obtain, as a by-product, an estimate of the gluon condensate ($\text{α}{}_{\mathrm{<mtext>s</mtext>}}\text{/π)〈π|F}{}_{\mathrm{\mu \nu }}{}^{\mathrm{a}}\text{F}{}_{\mathrm{\mu \nu }}{}_{\mathrm{a}}\text{|Ω〈}$ and an estimate of the 0^? glueball mass which agrees with our previous estimates.     

Vacuum of the quantum Yang-Mills theory and magnetostatics

It is argued that since in asymptotically free Yang-Mills theories the quantum ground state is not controlled by perturbation theory, there is no a priori reason to believe that individual orbits corresponding to minima of the classical action dominate the Euclidean functional integral. To examine and classify the vacua of the quantum gauge theory, we propose an effective action in which the gauge field coupling constant g is replaced by the effective coupling $\text{g}\text{(t), t =}\text{ln}\text{[}\text{F}{}_{\mathrm{\mu \nu }}{}^{\mathrm{a}}\text{)}{}^2\text{μ}{}^4\text{]}$. The vacua of this model correspond to paramagnetism and perfect paramagnetism, for which the gauge field is F_μν^a = 0, and ferromagnetism, for which (F_μν^a)² = λ², i.e. spontaneous magnetization of the vacuum occurs. We show that there are no instanton solutions to the quantum effective action. The equations for a point classical source of color spin are solved, and we show that the field infrared energy becomes linearly divergent in the limit of spontaneous magnetization. This implies bag formation, and an electric Meissner effect confining the bag contents.     

Infrared-radio frequency double resonance observations of pure rotational Q-branch transitions of methane

The $\text{F}{}_2{}^{\mathrm{(2)}}\text{← F}{}_1{}^{\mathrm{(2)}}$ and $\text{F}{}_2{}^{\mathrm{(2)}}\text{← F}{}_1{}^{\mathrm{(1)}}$ transitions of the J = 7 levels of the ground state of CH₄ have been observed by infrared-radio frequency double resonance using the 3.39 μ HeNe laser line. The transition frequencies are 423.02 ± 0.02 MHz and 1246.55 ± 0.02 MHz, respectively. Using these frequencies and the splitting of the E and F₂ levels of the J = 2 state calculated from the molecular beam magnetic resonance spectra of Ozier, the centrifugal distortion constants are derived to be D_t = 132933 ± 10 Hz, H_4t = ? 16.65 ± 0.2 Hz, and H_6t = 10 ± 1 Hz. The J = 15 E⁽¹⁾ → E⁽²⁾ microwave transition is predicted as 14150 ± 9 MHz.     

Vector-axial vector interference terms in inelastic neutrino reactions extrapolated from single-pion photoproduction

By use of the generalized scaling sum rules the vector-axial vector interference terms in the scaling limit of the inelastic neutrino reactions are calculated from the absorptive parts of the single-pion photoproduction amplitudes at zero momentum transfer. The photoproduction amplitudes are evaluated by use of the results of multipole analysis. With the optimum values for the two parameters of the generalized scaling as determined in previous works, we have obtained F₃^νN(ω) which leads to good agreement with experiment in the ration of $\text{σ}{}^{\mathrm{<mtext>\nu </mtext><mtext>N</mtext>}}\text{/σ}{}^{\mathrm{<mtext>\nu </mtext><mtext>N</mtext>}}$. However, the zeroth moment in $\text{x( = 1/ω), ∫}{}_0{}^1\text{d}\text{x(F}{}_3{}^{\mathrm{<mtext>\nu </mtext><mtext>p</mtext>}}\text{+ F}{}_3{}^{\mathrm{<mtext>\nu </mtext><mtext>p</mtext>}}\text{)}$ turns out to be smaller than half of the value predicted in the fractionally charged quark model.     

Spectroscopy of 62Ni with the 61Ni(d, p) reaction

Differential cross sections, vector and tensor analysing powers have been measured for the ⁶¹Ni(d, p) reaction at a deuteron energy of 12.3 MeV. Most of the 30 transitions observed below 8.5 MeV excitation are dominated by a single j-value, which was determined from behaviour of the analysing power data. For a number of transitions it was possible to make unambiguous j-assignment relying on the established j-dependence of the T₂₂ tensor analysing power. The deduced spectroscopic factors indicate that the full strength of neutron transfer to the ($\text{2p, 1f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) and $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ orbits was found and seven $\text{5}\text{2}{}^{\mathrm{+}}$ transitions were located above 5.3 MeV. The separated strengths of the $\text{3}\text{2}{}^{\mathrm{?}}\text{,}\text{1}\text{2}{}^{\mathrm{?}}\text{and}\text{5}\text{2}{}^{\mathrm{?}}$ transitions are compared with shell-model calculations for the low-lying states of ⁶²Ni.     

Structural evidence of 2kF commensurability effects in TTF-TCNQ under high pressure

We have shown that the Fermi wave vector describing the low temperature longitudinal distorsion of TTF-TCNQ moves under hydrostatic pressure from an incommensurable value ($\text{2k}{}_{\mathrm{F}}\text{= .295 b}{}^1$) at ambient pressure to a commensurable one ($\text{2k}{}_{\mathrm{F}}\text{= b}{}^1\text{/3}$) around 14.5 Kbar. This value is maintained until 17.5 Kbar at least. Between these two pressures the commensurable low temperature superstructure has a periodicity a × 3b × c.     

π+-Electroproduction of hydrogen near threshold at four-momentum transfers of 0.2, 0.4 and 0.6 GeV2

The reaction e + p → e′ + π⁺ + n was measured near the one pion threshold, detecting the final electron and neutron in coincidence for values of q² = 0.2, 0.4 and 0.6 GeV². The normalized axial vector form factor to the nucleon $\text{F}{}_{\mathrm{<mtext>A</mtext>}}\text{(q}{}^2\text{)}\text{F}{}_{\mathrm{<mtext>A</mtext>}}\text{(0)}$ was determined from the data within a theoretical framework based on PCAC and current algebra.     

Necessary and sufficient conditions for the existence of a lagrangian. The case of quasi-linear field equations

Necessary and sufficient conditions for the existence of the Lagrangian associated with given field equations of motion are investigated. For the quasi-linear equations A_ab^μν(x^λ, φ^c, φ_?^c)φ_μν^b + B_a(x^μ, φ^b, φ_ν^b) = 0, the complete necessary and sufficient conditions are obtained, resorting to the formalism of an exterior derivative. It is emphasized that, to find expressions of these conditions, the anti-symmetric parts of the second derivatives of a Lagrangian, $\text{R}{}_{\mathrm{\mu \nu }}{}^{\mathrm{ab}}\text{= (}\text{?}{}^2\text{L}\text{?φ}{}_{\mathrm{\mu }}{}^{\mathrm{a}}\text{?φ}{}_{\mathrm{\nu }}{}^{\mathrm{b}}\text{?}\text{?}{}^2\text{L}\text{?φ}{}_{\mathrm{\nu }}{}^{\mathrm{a}}\text{?φ}{}_{\mathrm{\mu }}{}^{\mathrm{b}}\text{)/2}$, which disappear in the field equations, take an important role. The procedure to construct the Lagrandian associated with the field equations is also presented.     

Scaling violation,the Callan Gross relation,and color excitation in electroproduction

The Callan-Gross relation is shown to be consistent with MIT-SLAC data for $\text{σ}{}_{\mathrm{<mtext>L</mtext>}}\text{(Q}{}^2\text{)}\text{σ}{}_{\mathrm{<mtext>T</mtext>}}\text{(Q}{}^2\text{)}$ for x ? 0.33 in deep inelastic eN scattering, despite the fact that these data are taken in the large Q² region where F₁ and F₂ individually exhibit scaling violation. Comparison is made with asymptotic freedom predictions, and color excitation is proposed to explain large values of $\text{σ}{}_{\mathrm{<mtext>L</mtext>}}\text{σ}{}_{\mathrm{<mtext>T</mtext>}}$ at small x.     

Observation of compensation effects during the thermal dissolution of aluminum oxide layers on tungsten and molybdenum 〈111〉 and on tungsten {110} in the presence of electric fields

Aluminum oxide layer dissolution was studied between 700 and 1200 K in the substrate areas of W〈111〉, Mo〈111〉, and on W{110} by means of FEM. Varying the electric field strength, F, between +45 and $\text{+105}\text{MV}\text{cm}$, two types of dissolution could be observed: dissolution by surface diffusion (low F's) and dissolution by ion desorption (high F's). It is assumed that aluminum suboxides — preferentially AlO — are involved in the dissolution processes. The preexponential factors, A_F, of an Arrhenius-Frenkel type equation were measured as a function of F. The field dependence of A_F is determined by the dissolution mechanism: (a) dissolution by diffusion: $\text{log}\text{A}{}^0{}_{\mathrm{F}}\text{=}\text{log}\text{A}{}^0{}_0\text{?}\text{ΔμF}\text{2.3k}{}^1\text{T}$ (μ  molecular dipole moment, ¹T ≡ isokinetic for W〈111〉, log A⁰₀ = ? 6.0 and ${}^1\text{T = 940}\text{K}$; for Mo〈111〉, log A⁰₀ = ? 3.1 and ${}^1\text{T = 860}\text{K}$; and (b) dissolution by ion desorption: $\text{log}\text{A}{}^{\mathrm{+}}{}_{\mathrm{F}}\text{=}\text{log}\text{A}{}^{\mathrm{+}}{}_0\text{+}\text{n}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{e}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{F}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{2.3k}{}^1\text{T}$; for A⁺₀ = ? 22 and ${}^1\text{T = 1200}\text{K}$; for W〈111〉, log A⁺₀ = ? 21 and ${}^1\text{T = 1200}\text{K}$. Using earlier proposed safeguards, isokinetic relationships (compensation effects) could be established for each of the two dissolution processes. The coordinates of the isokinetic points have the following average values: $\text{log}{}^1\text{A}{}^0{}_0\text{= 2.5}$ and ${}^1\text{T = 920}\text{K}$ for diffusion; $\text{log}{}^1\text{A}{}^{\mathrm{+}}{}_0\text{= ? 1}$ and ${}^1\text{T = 1240}\text{K}$ for ion desorption. The entropy changes (at $\text{T =}{}^1\text{T}$, zero field strength, and unit pressure) for the phase changes: solid layer → diffusion layer and solid layer → ion gas, are of the order of $\text{30}\text{cal}\text{K}$ · mol and $\text{90}\text{cal}\text{K}$ · mol, respectively. The two dissolution mechanisms can be described by the following Arrhenius-Frenkel type equations:

$\text{τ}{}^0{}_{\mathrm{F}}\text{=}{}^1\text{A}{}^0{}_0\text{exp}\text{[}\text{? (E}{}^0{}_0\text{+ ΔμF)}\text{k}{}^1\text{T}\text{]}\text{exp}\text{[(}\text{E}{}^0{}_0\text{+ ΔμF)}\text{kT}\text{]}$

for diffusion and

$\text{τ}{}^{\mathrm{+}}{}_{\mathrm{F}}\text{=}{}^1\text{A}{}^{\mathrm{+}}{}_0\text{exp}\text{[}\text{? (E}{}^{\mathrm{+}}{}_0\text{? n}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{e}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{F}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}\text{k}{}^1\text{T}\text{]}\text{exp}\text{[(}\text{E}{}^{\mathrm{+}}{}_0\text{? n}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{e}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{F}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}\text{kT}\text{]}$

for ion desorption.     

The dipole moment of thioformaldehyde in its singlet and triplet π1 − n excited states

Laser-induced fluorescence excitation has been used to measure Stark splittings of selected lines in the $\text{A}\text{?}{}^1\text{A}{}_2\text{-}\text{X}\text{?}{}^1\text{A}{}_1$ and $\text{a}\text{?}{}^3\text{A}{}_2\text{-}\text{X}\text{?}{}^1\text{A}{}_2$ band systems of H₂CS in electric fields up to 13 kV/cm. The derived excited state a-axis dipole moments are 0.820 ± 0.007 D for the 4¹ level of the ¹A₂ state; 0.838 ± 0.008 D for the zeroth vibrational level of ¹A₂; and 0.534 ± 0.015 D for the zeroth vibrational level of the ³A₂ state. These results are compared with the corresponding values of H₂CO, and interpreted in terms of the changing localization of the π and $\text{π}{}^1$ orbitals accompanying electronic excitation.     

Local field theory of the dual string

We develop a (classical) local field theory which contains as a special solution the (classical) dual string recently discussed by Goddard, Goldstone, Rebbi and Thorn. The basic field is a gauge field F_μν(x), and the Lagrangian is given by $\text{(}\text{?1}\text{2α'}\text{)√F}{}^2$. We treat the case of closed strings (corresponding to the Shapiro-Virasoro model) where F_μν can be expressed in terms of potentials A_μ. Quantization of F_μν is briefly discussed, but a more thorough discussion is postponed.     

Tabulation of hyperfine splittings in rotational F1 and F2 levels of the ground vibrational state of 12CH4 for J ≤ 20

To a good approximation, hyperfine splittings for F₁ and F₂ rotational levels of the ground vibrational state of ¹²CH₄ depend linearly on three hyperfine interaction parameters. Coefficients in these linear expressions have been computed in a relatively simple manner and tabulated for levels with 1 ≤ J ≤ 20. The hyperfine pattern for the $\text{J = 7 F}{}_2{}^{\mathrm{(2)}}$ level computed from these expressions using values for the three hyperfine interaction parameters reported recently by Yi, Ozier and Ramsey (1) agrees well with the pattern obtained from new HeNe laser measurements of Hall and Bordé (2) on the $\text{P(7) F}{}_2{}^{\mathrm{(2)}}$ line of the ν₃ band of methane.     

A note on the momentum distribution function for an electron gas

The one-electron momentum distribution function $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉}$ for an electron gas is investigated by a diagrammatic analysis of perturbation theory. It is shown that $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉}$ has the following exact asymptotic form for large k (k ? p_F; p_F, the Fermi momentum): $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉 =}\text{4}\text{9}\text{(}\text{αr}{}_{\mathrm{s}}\text{π}\text{)}{}^2\text{×(}\text{p}{}_{\mathrm{<mtext>F</mtext>}}{}^8\text{k}{}^8\text{) g?(0) + ?}$, where g?(0) is the zero-distance value of the spin-up-spin-down pair correlation function. The physical implications of the above asymptotic form are discussed.